Jim Hand - Pontiac Ace

Dave was co-partner with ace mechanic Demetri Kokkoris,
the team known as SUPERJET SPECIALTIES of Queens, NY.  
Superjet rebuilt and blueprinted musclecar engines, specializing in modification and custom tuning of
Rochester Quadrajet carburetors.

Below is an article written by Dave regarding camshaft and cylinder head selection for the Pontiac V-8, one of several articles that appeared in Pontiac musclecar related publications.  

Following is some additional info by highly experienced Pontiac ace, Jim Hand.

Due to time constraints, Dave is no longer able to answer automotive questions.

Blueprint Tuning the Pontiac V-8:

A Guide for Cam & Head Selection

Valve timing and compression pressure are the two most important factors that effect an engine's performance.  All other modifications will be futile unless the valve events and compression pressure have been carefully dialed in per desired state of tune. Through experimentation, we have developed the following "formulas" which can help when attempting to create an optimum parts combo.

The optimum (maximum) cranking cylinder compression pressure for a performance/street application using 93 octane fuel = 160 -170 psi

Changing the position of the camshaft (and thus intake valve closing event) by 4 degrees changes cranking cylinder pressure by about 5 psi. (Advancing increases pressure, retarding decreases pressure.)

Changing the compression ratio by 1 point changes cranking cylinder pressure by about 20 - 25 psi.

CAMSHAFT  (all cam and valve event figures measured at .050" lift)

The first thing is to choose a cam grind that will yield the desired manner of operation.  We know from experience that a cam such as Pontiac's 068 - "H.O." (211/225 - 116 lobe sep.) or similar will produce a broad torque band in a 400, and thus excellent all around power, while yielding a pleasant idle and relatively good fuel economy.  We also know that a cam such as Pontiac's 041 - "RA IV" (230/240 - 114) or similar will produce max torque at a higher rpm, thus greater horsepower, but at the expense of lesser low end torque, poor idle, poor economy, and excessive emissions.

Any Pontiac enthusiast who seeks improved performance but intends to use his/her car as a "daily driver" should aim for a maximum camshaft intake duration of 210 - 220 degrees, depending on the engine/situation.  Exhaust duration can be a bit greater without an adverse effect.  For those who are ONLY concerned with obtaining the lowest possible quarter mile e.t. ("race" use), cam durations upwards of 225 degrees will be more effective.  Such larger duration cams are NOT appropriate for use in "daily drivers" because of their adverse effect on economy and street behavior.  A car that is used nearly everyday, city and highway, heat wave or snow storm, must be dependable, efficient, and convenient to use.  DO NOT make the age old mistake of creating a "race" type vehicle which is actually intended for "daily driver" usage.

Remember that engine displacement is an important factor when choosing a cam grind.  Bigger engines can tolerate larger durations.  A Pontiac 068 grind will act a bit "wild" in a 350, but act "mild" in a 455.  Also, heavier vehicles, and vehicles with low numerical rear-end gearing will be better off with a lesser cam duration, where lighter vehicles, and vehicles with higher numerical rear-end gearing can get away with a greater duration.

COMPRESSION  

The "compression ratio" (also referred to as "static" compression)  is determined by the cylinder head combustion chamber, head gasket, deck height, and piston face volumes (dead volume), with respect to the total cylinder volume swept by the piston (swept volume).  

The intake valve closing event is determined by the intake duration and intake lobe centerline of the camshaft, as well as the actual position of the cam as installed with respect to the crankshaft.  

Actual compression pressure, also referred to as "dynamic compression",  is determined by both the "static" measured compression ratio, and the intake valve closing event.  The dynamic compression is the compression pressure the engine actually sees, regardless of the measured ratio, and is all that really matters.  Consideration must be given to the matching of the cam and heads to yield the desired compression pressure.  It is too common an error that a new cam grind is swapped in without paying attention to compression, resulting in too low a compression pressure.    

Optimum cranking compression pressure when using 93 octane fuel is 160 - 170 psi, at least with old Pontiacs.  Too high a compression pressure will yield too high a peak combustion pressure and thus cause detonation.  Too low a compression pressure will yield a low combustion pressure and thus poor performance and poor economy.

Some well-blueprinted Pontiacs have been known to handle pressures upwards of 170 psi when using 93 octane fuel without detonation.  But considering the inconsistent and often poor quality of today's fuel, it is much wiser to aim on the low side of what might technically be the maximum useable pressure.  Detonation must be avoided at all costs.  We have found that pressures of 190+ psi will cause detonation, overheating, "run-on", etc., unless 98+ octane fuel is used, or ignition timing advance is reduced way below optimum.  Remember that you should expect to often receive fuel with an actual octane rating of less than what you're paying for.  Also, at any given time, a few cylinders may be running a tad hot/lean due to one of several common problems (uneven coolant flow through the block, uneven fuel mixture distribution, etc).  For street use, we vote to dial in a "safety zone" and stay detonation-free.

EXAMPLE

Begin your project by measuring the existing cam and compression specs as a starting point, and then use the previously mentioned "formulas" to get an idea of what parts are needed to create an optimum combo.  It is very important to measure all the variables of your own project engine.  Do not rely on existing texts/manuals for measurements.  Texts are often inaccurate, and original parts of your engine may have been modified or swapped prior to your ownership.

We recently disassembled an excellent bone stock 1975 Pontiac 400 from a Trans-Am.  Actual compression ratio was measured at 7.8:1.  Cam was a Pontiac 066 and measured in at 197/206 - 112, as specs call for.  Even with the original stretched timing chain, cam was found positioned at a 107 degree intake lobe centerline, also as specs call for.  This places the intake closing of this cam at 26 degrees abdc, as measured.  Before we had disassembled the engine, cranking cylinder pressure was measured at 135 psi across the board.

In order to increase performance to the desired level, we decided to replace the original 066 cam with a Pontiac 068 cam.  If we install the 068 cam "straight up", the intake closing event will be at 39 degrees abdc.  This is 13 degrees LATER than with the original cam (13 degrees retarded from original). Refer back to our formulas, and note that the engine would now produce roughly 15 psi LESS compression pressure with the 068 cam due to the later intake closing - from 135 psi down to 120 psi.  A compression pressure of 120 psi is too low to support optimum efficiency.  Desired pressure is 160-170 psi, so we need to increase pressure by 40-50 psi.  Refer back to our formulas, and note that it is possible to gain 40-50 psi by increasing the compression ratio by 1.5 to 2 points.  Our target compression ratio is thus 9.5:1.  In order to reach this compression ratio with a .030" overbore and typical flat top replacement pistons, we'd need heads with 82cc combustion chambers.  Since we cannot readily get our hands on heads with such a chamber size, we've chosen a pair of cheap and plentiful 93cc "6X" heads (off a `77  350).  These heads will be milled .040" to achieve a chamber size of 86cc.  The compression ratio will be about 9.2:1.  Estimated compression pressure is 150-155 psi - close enough, considering the ease and low cost of this plan.

To gain a bit more psi, we can advance the cam.  Or, we can try a different cam grind with similar duration to the Pontiac 068 cam, but with a tighter lobe separation which will automatically advance the intake closing event with relation to the other events.  The amount of overlap gained by reducing the lobe separation from say 116 to 112 degrees on cam with 068 size duration will not cause any measurable adverse effect on economy.

A pair of older "16", "62", or similar "high compression" heads could have been chosen, but with their small 72cc chambers, estimated pressure would be up in the 185+ psi range with our combo - too high for our purposes.

Keep in mind that if the wild Pontiac 041 cam was installed "straight up" in the above engine, the intake closing event would be 47 degrees abdc, 8 degrees later than with the 068 cam.  This alone would drop pressure by about another 10 psi, and thus the 72cc heads (10.4:1 c.r.) might just slip by as detonation-free.  Estimated pressure is 175 psi - right on the line.      

OVERLAP

A common misconception is that camshaft overlap reduces cranking cylinder compression pressure.  Not so.  Overlap indeed reduces peak combustion pressure by diluting the incoming intake charge with exhaust, and by sending some of the combustible mixture out past the exhaust valve before ignition, but this does not affect compression pressure.  The intake valve closing event is the only cam related factor that noticeably affects compression pressure.

An experiment was conducted: a given cam, as installed in a custom 9.9:1 c.r. 455, yielded about 185 psi.  Detonation was evident.  Cam had only 1 degree of overlap, and the intake closing was at 39 degrees abdc.  A new "larger" aftermarket cam with a full 14 degrees of overlap, but SAME intake closing as the previous cam (39 degrees), was installed.  (New cam had greater duration and a tighter lobe separation.)  Cranking cylinder pressure was exactly the same - 185 psi.  Other engine characteristics changed, but detonation was still present.  (Fuel metering and ignition timing were correctly tuned for each application.)

The first cam was then refitted, but was retarded 10 degrees from the original position so that the intake closing was now at 49 degrees abdc.  Pressure dropped from 185 to about 170 - the tendency of detonation was noticeably reduced.  (The optimum set-up for this particular engine was ultimately achieved by reducing the compression ratio and running the smaller cam slightly advanced.)

Cylinder compression pressure effects the amount of peak combustion pressure to a greater extent than does the amount of overlap, per degree of change.  So, for those trying to reduce detonation problems in original "high compression" engines by merely swapping the cam, be sure to get a cam with a wide lobe separation and thus a relatively late intake closing.  Note that TOO late an intake closing event will adversely effect street performance.  Such allows an excessive amount of fuel mixture to be pushed back into the intake, creating significant reverse pulses which will hurt low end performance and can even upset carburetor operation.

The above information is general, and is intended as a guide.  Figures are approximate, and will vary with different situations.  Also, remember that "budget" measuring devices often have large error margins.  (Inexpensive compression gauges will vary from each other by as much as 15+ psi, etc.)  

It's always a good idea to consider tech articles and recommendations, but you can never avoid experimenting with your own project when optimum results are desired.  If you want it done right, you must make your own educated decisions based on your own specific data, and do some trial & error testing, because  every situation is unique.

Concept and article by Dave Miranda
Mechanical tests conducted by Demetri Kokkoris and Dave Miranda  

 

ABOVE: The Official "Elf-Mobile" - 1968 G.T.O., owned and raced by Demetri Kokkoris.

*********************

Due to time constraints, Dave is no longer able to answer automotive questions.

Additional info directly related to the above subject, emailed to me in 1998 by highly experienced Pontiac ace, Jim Hand.  
Thanks for the input, Jim!  -Dave

When looking at cams and compression, the real relationship is when the intake valve closes in relation to BDC.  Actual compression of the fuel/ air mixture does not begin until the intake valve closes, regardless of the static compression ration (CR) rating.  My Performance Trends Engine Analyzer will calculate the dynamic CR based on the two factors - static CR and intake closure point.  Here are several examples, all with an assumed static CR of 10:1 with a 455:

Factory Grind 066  Intake is 197 with LC at 107, dynamic CR = 8.21

Factory Grind 068  Intake is 212 with LC at 113, dynamic CR = 7.25

Factory Grind 744  Intake is 224 with LC at 113, dynamic CR = 6.67

Factory Grind 041  Intake is 230 with LC at 112, dynamic CR = 6.65

Comp Cams 268  Intake is 218 with LC at 106, dynamic CR = 7.62

My Wolverine 234/244  Intake is at 107 with LC at 107, dynamic CR = 6.84.

What is the significance of these numbers?  The 066 and the CC 268 would be real pingers in an engine with higher rated static CR.  The 041, 744, and my Wolverine would be less likely to detonate.  The earlier lobes (intake closing points) of the 066 and CC 268 make the engine think that it has higher static CR.  Longer durations tends to minimize this tendency, but does not preclude it.

For example, the same Ultradyne cam grind - 239-247 at a different lobe separations (LS) show the same characteristics.  The normal 239/247 has the intake at 104 (exhaust at 116) and an LS of 110, and has a dynamic CR of 6.90.  However, using the same lobe profiles but placing the intake at 100 and the exhaust at 112 for a 106 LS (which is essentially advancing the intake closing event by 4 degrees compared to the previous), the dynamic CR jumps to 7.19.  If the engine was marginally OK with the 110 LS cam, it could be ruinous to install the 106 LS cam.

Be very careful of any aftermarket versions of Pontiac grinds. Invariably, they have advanced the intake lobes in order to improve low rpm throttle feel, but give the engine more dynamic CR!

Dave, I have enjoyed reading your sensible post concerning compression and valve timing. Your testing seems very comprehensive, but I don’t believe that it can be considered a benchmark for dictating the maximum CR of all other combinations of blocks, deck clearances, heads, cams, timing, gas quality, etc.  Like you, I try to help others get a little more out of their engines, while suggesting the cheapest and easiest way.  How do we help the guys that know the technical aspects to live with optimum CR without leading others astray?

I know someone who is extremely well informed about a wide range of auto subjects.  He has been working for several years on his dream 400 setup.  But he was scared so bad about the dangers of high CR that he set his 400 at just 9.25.  Yet, he has spent a lot of money on ignition, head work, special pistons, etc., but the thing that will make the most difference in actual engine performance is not set to optimum!  In addition, he is going to try to run a "specially selected" cam with the intake lobe at 112.  Not only does he not have adequate static CR, but the 112 lobe cam will make it even worse.

From my view, anyone could safely run 9.7 to 10 CR on a daily driven street/strip car, providing the engine was setup for that with correct assembly, proper ignition and carb work, correct engine cooling, and dependable pump gas.  My brother, friend, and I have all done it for years with not a trace of problems.

Here are the steps I take to minimize high-CR detonation related problems:

When preparing the heads, as part of the porting we lay back the shrouding on both sides of the intake valve.  We start cutting at the base of the overhang (chamber floor), and straighten and tilt back the overhang such that it does not get closer to the valve as the valve lifts.  All chamber edges are rounded/smoothed.  The entire chamber, including both valves, are polished to a bright luster.  The piston tops are prepared by rounding the edges of the piston and the valve relief's, and then they also are polished.  This practice is based on my desire to eliminate any potential hot spots, as well as suggested by KB Piston Co.  KB states that the polished surfaces will tend to reflect heat back into the chamber thus generating more combustion pressure and power.  We also carefully prepare each spark plug by filing all edges to a rounded surface.  So do any of these things help?  They certainly can't hurt, and by minimizing every possible hot spot, I feel even safer.

Now for the most important step of all regarding CR.  Set the engine deck to 0. This will vastly improve quench/squish, which in turn improves fuel air mixing. Better fuel mix burns faster and more predictable, thus requiring less ignition advance.  Presto!  We have won twice!  More CR due to the 0 deck, and less timing required so we can run even more CR.  When I made this simple change (about .020 off to get to 0 deck), my engine ran quickest and fastest with 30 degrees total timing as opposed to 34 total with the .020 deck.  This should be the first step in setting the final CR in every serious engine build-up!  On the reverse side of this effect, cutting the pistons tops (and thus increasing effective “deck volume”) may aggravate a detonation problem because of the poorer fuel mixing!  Even though the static CR is lower, the timing has to be advanced to get any power, and we are back into the detonation problems.

And don’t forget temperature control!  I was at the drag strip last night in 86 degree weather.  While in line, the engine got up to 190, so I sped the rpm up to about 1500 for 20 seconds. It dropped to 180, and by the time we hit the finish line at 111.5 mph, it had dropped down to 175.

-Jim Hand,  May 1998



Follow up by Dave...

Jim’s above approach using “dynamic CR” figures (via an analyzer or calculator) as a guide for dialing in the optimum cam/head combo (optimum peak pressure) is essentially the same premise as using measured cranking compression pressure as a guide for the same.  In both approaches, we are studying the relationship between the actual physical ("static") compression ratio and the timing of the intake valve closing event... which together make up the "dynamic compression", or compression pressure the engine actually sees.  

The method of calculating dynamic CR on paper (or on a computer) is nice since it can be done without actually assembling and testing a physical engine.  Of course, assembling a proposed combo and then measuring the results will deliver an actual physical indicator of what is really taking place.  As well, it is good for comparing the measured stats of your current set-up to a new proposed set-up in order to observe the true degree of change and establish benchmarks for your own engine.  

As Jim has pointed out in the past, the “optimum” measured cranking compression pressure figure will vary from engine to engine… while 170 psi may be “optimum” in one set-up, 200 psi may be optimum in another set-up, and so on… and then of course we must remember that there will be a good deal of error with typical compression gauges, and differences in the measurement procedure itself (condition of battery, rpm of starter motor, ambient temperature, ambient pressure, temperature of engine, etc… all may effect a cranking compression pressure reading by easily 10% or 15%.)    

So it appears that the only way to arrive at the optimum dynamic compression ratio figure for one’s own situation is to experiment… which may mean more than one swapping of cam/heads.  Many weekend hobbyists may not have the time or budget to reconfigure their engine more than once, so this is why, when in doubt, I personally vote to aim on the low side when plotting “optimum” dynamic CR. Just my personal opinion.

For STREET performance use where no serious competition is involved, running a slightly lower than “optimum” dynamic CR will still net you excellent performance and economy, even if you might be down on power by a tiny amount compared to true "optimum" dynamic CR.  HOWEVER, running a slightly higher than optimum dynamic CR may yield realistic headaches such as detonation, run-on, hot operation, etc.  If you can only rebuild your engine one time, which scenario would you rather have?  I personally vote to stay detonation-free at all costs, even at the possible expense of a tiny amount of performance.

However, needless to say, if one is serious about squeezing out every last drop of performance for competition use, then experimenting is absolutely necessary to arrive at the true optimum state... be prepared to swap parts more than once.  But after all, isn't that what hot-rodding is all about?

To Read More, Click On Link:

http://www.davemiranda.com/dmhotrods.htm]http://www.davemiranda.com/dmhotrods.htm[/url]

 
When The Flag Drops,,,



The Bull Chit Stops,,,


P. Engineer, Engine Builder

Pretty good post tuff.
The only thing is we don't have good dependable pump gas anymore, those days are long gone.  
Engine builder,self taught auto body guy.
Horsepower sells engines and torque wins races

Yep, "those were the days my friend, we thought they'd never end"

 
When The Flag Drops,,,



The Bull Chit Stops,,,


P. Engineer, Engine Builder

How true and how wrong we were.
All good things must come to a end at sometime I guess.  
Engine builder,self taught auto body guy.
Horsepower sells engines and torque wins races

Nice post Tuff, timely too!
Steve  
A little help... 'cause we don't all have to learn the hard way!

Thanks Steve.,. let the young crowd learn the hard way.,. pain is the best teacher.

 
When The Flag Drops,,,



The Bull Chit Stops,,,


P. Engineer, Engine Builder

good post tuff!   now you know how i got my 10.3 to 1 6x headed 468 to live on the street on 93 pump gas.

i went to a pontiac show in kc about 10 years ago and set in on one of jim hands seminars on exhaust tuning. one of the nices guys you will ever meet! the next day we went to the race track to watch the big red waggon run. what a week end!  
76 455/4spd TRANS AM
69 GRAND PRIX 406/5SPD

Thanks for posting the article Tuff. It's the same article from the link I posted on Rustyskills thread. Not sure if you had this article previously or not.  
Jim,

Thanks for bringing that article to my attention again.,. it was there.,. somewhere, and now it's posted.,. thanks to you.

 
When The Flag Drops,,,



The Bull Chit Stops,,,


P. Engineer, Engine Builder

Sweet article. Got the rodent in my head chasing the cheese turning the wheel a wee bit faster again.
I went searching for the 068 cam specs to see how I fare and see if I have room for some adjusting from where I'm at
Don't get me wrong I have said I don't wanna make major changes but push comes to shove I shall.
But I'm not far above cam wise from where that 068 is.
I could use lower gearing and somr suspension mods...
But feel I can still get streetable with the engine as it sits.
Cam across this while looking about and doing some more studying of where I wanna go once I get some things squared away with cleaning up my interior.. atm gutted.
But check out the link.. may have read, posted etc... But feel some noobs to pontiac lookin at their first build may be able to get a base as to what  they're shooting for.

http://www.pontiacstreetperformance.com/psp/camselect.html

Hope you enjoy.  
Viagra and Torque are one in the same they both get you up!

Drag Racing with Jim Hand – Part 1: Introduction to the Series
March 16th, 2010 Posted in Drag Racing with Jim Hand . Technical Articles By Jim Hand

This complete series of articles was prepared in the time period 1995-1996, and there are various references to my wagon and it’s performance. Please note that the wagon serves as a sort of test bed, and we occasionally change parts, rpm, shift points, converters, cams, etc, so driving styles, engine rpm, and especially performance may be different today. Please read these articles in that context, and if there are questions, contact me directly through E-mail.

A few words about this writer are in order so that you may better understand our approach to the sport of drag racing. I certainly qualify for the somewhat questionable title of “graybeard”, because I am on the downhill side of 60. However, I still regularly compete at sanctioned races with my ’71 LeMans wagon, and do win my share. My racing “career” began in about 1950 when I challenged my neighbor of about the same age for a top speed race. He was driving an International F-30 farm tractor, and I was on a Ford 9-N tractor. Of course, I won! My brothers and I fairly regularly ran each other’s ’37 Ford sedan, ’41 Pontiac 6, and ’39 Ford coupe in that time period. Since we ran on graveled roads, the winner was always the one who got in front first! My first trip to a real strip was in 1958, and my first sanctioned race was in 1960.

Since that time, we have had the opportunity to race at many strips in the Mid-West, and have always ran Pontiacs. While we have won some money purses, we are in no way professional racers. The primary purpose of our racing during the past 9 years was to satisfy the urge to compete while trying to find the lowest cost methods to obtain competitive performance with the LeMans wagon.

This series will attempt to provide enough information about drag racing to allow each of you to make your first trip to the strip without fear of destroying your car, or embarrassing you or your fellow racers. We will not discuss whether racing is appropriate, or when it should be held, but rather how to do it, and how to enter your pride and joy in this aspect of competition if You decide to do so.

All members are encouraged to contact me, preferably via letters, to suggest what you would like to see discussed in this column, or to review specific questions for you about drag racing. Experienced racers are especially encouraged to write so that we will be familiar with all the aspects of the sport.

http://www.dapa.org/drag-racing-with-jim-hand-part-1-introduction-to-the-series/#more-206

 
When The Flag Drops,,,



The Bull Chit Stops,,,


P. Engineer, Engine Builder

Drag Racing with Jim Hand – Part 2: History of Drag Racing
March 16th, 2010 By Jim Hand

Auto racing has transpired almost since the first two auto owners encountered each other. Racing has taken many forms: Hill climbs, cross country races, top speed contests, closed course races, endurance races, and standing start racing. The latter is what we know today as drag racing. Two vehicles line up side by side and race to some given point, usually 1/8 or 1/4 mile. In the purest form, the winner of the race is the vehicle that crosses the finish line first.

How did this sport get started? The roots can be found in top speed racing at the “dry lakes” in California as early as 1934. Enthusiasts discovered the dry lakes, such as Muroc in the high desert, were flat, relatively smooth, and had no driving restrictions. Their vehicles were driven to the dry lakes, where various components such as fenders, windshields, and tops were removed in preparation for the top speed runs. In those early days, speeds of 100 MPH was considered quite fast. There were no purses, trophies, safety checks or rules, and the racers ran just to get a top speed number. In 1937, the Southern California Timing Association was formed and this group pulled together various Clubs to establish classes, some safety rules, and a schedule of four organized races per year. Such safety features as roll over bars and seat belts were mandated, and during this period through the start of the second World War, aftermarket speed accessories began to appear.

After the war and through the late forties, interest in cars and street racing exploded. According to the people that lived in Southern California during that period, the races usually began with a “Choose Off” where a driver would choose a competitor and they would have at it. In about 195O, the invitation to race was usually proffered by telling the opponent to “Drag It Out”. Apparently, that term, which originated in Southern California, is the basis for today’s “Drag Racing”. Other terms, such as “Dig” or “Digger” were used in other parts of the country, but did not become as common as “Dragging”.

The first organized drag races were held at unused air base runways, and the first commercial strip was apparently Santa Ana in Orange County in 1950. Typical 1/4 top speeds were in the 90's. The National Hot Rod Association (NHRA) was formed in 1951, and the initial purpose was to unite the various Car Clubs for regular safety checks, cruises, and reliability runs. As interest in racing was so high, NHRA quickly expanded into drag racing. Regional meets were implemented, and the NHRA “Safety Safari”, a group of people familiar with drag racing requirements and structuring, began to travel around the country helping local organizations conduct races. The first national event was held in Great Bend, Kansas, in 1955, and NHRA was off and running with the annual Nationals. Other associations have been formed since that time to promote drag racing, and some are still active.

In order to attract racers to a race, each racer has to have some chance to win occasionally. Thus, racing classes have been established based on some combination of cubic inches, rated horsepower, actual or factory weight, weight distribution, body styles, number of carburetors, or other factors that may affect the vehicle’s performance. With the proliferation of car models and engine sizes, vehicle sizes, front wheel drive, electronic fuel and ignition controls, turbo charging, etc., during the 70's/ 80's, the numbers of possible classes increased to an almost impractical number. The Car makers recognized the value of winning, and began to assign questionable low HP numbers to certain engines to increase their chance of winning. It became increasingly difficult to police the entries to insure proper classification, and the local drag strips could not conduct practical events with so many potential classes.

As a result of the above changes, a new type of drag racing was tried -Bracket Racing. Brackets of elapsed times in seconds normally run in the 1/4 by the vehicles in competition at a given track are delineated (such as O to 11.99, 12 to 13.99, and 14 seconds and slower). The drivers run a series of practice runs, called “time trials”, and based on the vehicle’s elapsed time, the driver selects an elapsed time (ET) to use in competition. This ET number, called a “dial-in”, is written on the vehicle windows, usually with white shoe polish, and the vehicle is classified accordingly. When it is time for actual competition (called “elimination’s”), that Bracket class is called as a group to the “staging lanes”. As the vehicles are paired up, the dial-in for each vehicle is entered into the track timing system by the Tower operator. The timing system delays the beginning of the starting lights sequence for the quicker car by the difference in the two dials. Thus, the slower car will be given a head start, and if both cars have a good start and run close to each of their respective dials, the cars will arrive at the finish line at about the same time. Bracket racing’s most valuable asset is that it minimizes cheating. Engine make, size, or power, vehicle type or weight, intake system, etc., is no longer of concern because the driver selects the dial-in. If the vehicle runs quicker than the dial, it automatically loses, and if it runs much slower than the dial, it will probably lose. Driving skills in quick and consistent starts, (“reaction time”), and the ability of the vehicle to run close to the dial-in are the keys to successful bracket racing.

Many drag racers prefer “heads up” racing where the car that finishes first is the winner. I also like that style, but I don’t like to compete against a 400 ci small block that is incorrectly entered as a 327, or a 455 Pontiac that is entered as a 350. Bracket racing immediately stops such games, and it allows local tracks across the country to conduct honest racing with a minimum of technical staff. Various associations presently conduct “heads up” or class style racing at larger events.

So whether it is the most preferred style, bracket racing is the most common form of drag racing available for us. Accordingly, the majority of our discussions will concern bracket racing, and as mentioned in the introductory column, we will try to make it easier for you to begin bracket racing, and possibly even become a regular contender.


Extra Info:

For those of you interested in drag racing history in general, and NHRA history specifically, the two hour video titled “Gathering Speed”, produced by Diamond-P Sports, Inc., traces the evolution of drag racing through the 70's. Many racing pioneers and their cars are featured in this interesting and informative video.

http://www.dapa.org/drag-racing-with-jim-hand-part-2-history-of-drag-racing/#more-203

 
When The Flag Drops,,,



The Bull Chit Stops,,,


P. Engineer, Engine Builder

Drag Racing with Jim Hand – Part 3: Track Layout
March 16th, 2010 By Jim Hand

In the early days of drag racing, an unused open stretch of road, or an unused airstrip was marked with a starting line and a finish line. An observer would be positioned at the finish line to determine the winner. A starter would stand in front of and between the cars and motion them to race with his arms, a flag, or a flashlight. Gradually, forms of communication systems were incorporated to provide winner information back to the starting areas, and PA systems were installed to relay the results to the fans/racers. Crude timing systems, such as stop watches, were used to obtain some performance data. Later, mechanical timers were adapted for Elapsed Time (ET) measurements, and speed measuring equipment was installed at the finish line to report terminal speed as well as elapsed time. In 1962, the automated starting system was introduced.This implemented a degree of fairness and consistency that had been lacking in the manual starting system. As semi-conductor technology became commonplace, advanced timing equipment was developed that provided much additional information to the racers. In addition to the ET and MPH, the time required to accelerate to 60' was included, and the racer’s “reaction time” (the time from the “start” signal until the vehicle’s front tires left the starting line) was provided. More advanced systems provide 1/8 mile and 1000' ET and MPH in addition to the above. The newer systems automatically consider red light starts, “Break-Outs” (running quicker than your dial), in addition to who gets there first, in determining the race winner. All of this data is printed out on time slips and given to the racers after each race. In later columns, we will discuss the use of some of these numbers in selecting your dial-in, and in running the next round of elimination’s. We will also discuss reaction time and improving same. Most drag strips now use similar timing and starting systems, so the following discussion generally covers all. Strip layouts vary as to position of pits, direction of track, method of staging race vehicles, separation of fast race cars from slower or driven cars, and rules governing classes. However, most use a “three yellow lights and green light (Go) starting system” known as the “Christmas Tree”, originally developed by Chrondek. The tree also has a tremendously bright red light that comes on if you leave too early. Most also have a “staging”, or positioning system, of two smaller yellow lights that defines the correct location of the car prior to starting the race. Finally, most trees have one additional light that indicates which car is quickest and will leave last during bracket races.
The diagram below illustrates the typical starting system, or “tree”. Note that the two sides are identical, so the following explanation applies to each. The top light (“Pre-stage”) is activated by the breaking of a light beam approximately 6? behind the starting line by the race vehicle’s front tire/wheel as the vehicle rolls closer to the starting line. The second light from the top (“stage”) is also activated by the front tire/wheel as the vehicle rolls closer to the starting line. (The actual distance between the two beams is set prior to a race by checking the “rollout” with a specified roller device in order to compensate for the different widths of light beams in use.) At this point, when both the pre-stage and stage lights are on, the vehicle is “staged” and the starting sequence can be activated. It is obvious that the front tire/wheel could be at a location between, slightly behind, or slightly ahead of the two lights due to different diameter tire/wheels, but if both are broken, the vehicle is still correctly staged.
There are various techniques of staging preferred by racers, but until we discuss this further in another column, I recommend you drive forward only until both prestage and stage lights turn on. Stopping at the position the stage light just comes on will improve your consistency in both reaction time and ET, and will provide the quickest ET. The “starter”, who watches over the previous race, the staging process, and general safety, activates the starting tree by operating a hand held control box. When he sees both vehicles are properly staged and the track is clear, he starts the tree sequence. The first large yellow (third lamp down) lights, .5 seconds later, the second large yellow lights, .5 seconds later, the third large yellow lights, and .5 seconds later, the green lights. If either vehicle leaves the front light beam (starting line) prior to the closure of the switch for the green light, the system detects the “foul” and turns on the big “RED” (bottom light). Note the reference to the green light switch closure. A perfect “light” or reaction time is .0 or .500, depending on how the local system prints out. In either case, a perfect light occurs when the tire leaves the starting line exactly when the green light switch closes. It takes some time for any bulb to illuminate after current begins to flow in the filament, and if you wait to see the green light before accelerating (“leaving”), your reaction time will be poor. More on this in later columns.

The finish line is equipped with a light beam across each lane. After a normal starting sequence by the racer and starting system, this light beam, in conjunction with the system timer and the starting line beam, will provide the actual elapsed time the vehicle was between the start and finish lines (ET). In addition, a light beam for each lane is located 100' before the finish line. The system timer measures the time the vehicle is in that last 100' and converts the time/ distance to speed in MPH. So we don’t get exact MPH at the finish line but an average speed for the last 100.

Some tracks use a different starting sequence for the very quick vehicles. It is called a “Pro” tree (or “.4 tree”) and normally operates as follows: The vehicles stage as noted above, but instead of the three large yellow lights sequencing down in discrete steps, they all flash together and .4 seconds later, the green comes on. This starting system tends to minimize red light starts. This system is mentioned only for information, and you should never have to drive with this starting system.

It is suggested you make a trip to your local track to review the track layout, and to observe the starting system for any variations from that described above.

http://www.dapa.org/drag-racing-with-jim-hand-part-3-track-layout/#more-197

 
When The Flag Drops,,,



The Bull Chit Stops,,,


P. Engineer, Engine Builder

Drag Racing with Jim Hand – Part 4: Preparing For That First Trip to the Drag Strip
March 16th, 2010 By Jim Hand

What could be simpler than taking you GTO, GP, FB, TA, 2+2, etc. out to the strip and shutting down that mouthy guy down the street with the Brand C. pile?

Maybe, if you have been there before, and your vehicle is running as well as it is capable of. However, if you are just getting started, there are some basic steps you should take before heading to the strip, and especially before you challenge anyone!

I regard drag racing as fun, and go primarily to improve my car’s performance, and to practice driving. Beating another car, or even winning a bracket, is only a secondary concern in most cases. With this approach, I don’t get upset when I lose, and if my car runs well and/or I drive OK, I consider that trip a success. I strongly recommend you make your first several trips with the same approach. Don’t go to try to beat someone; go to have fun and enjoy your car. Practice your driving skills while getting used to the performance of your Pontiac. Note the areas in which it is inconsistent, or where it sputters or bogs. Also, quietly review the performance of those other cars you would like to whip on. It makes absolutely no sense to challenge a car that is significantly quicker than your machine. You already know how the race will end! Good driving can possibly make up for some difference, but not more than a tenth of a second.

What about damage to your valuable machine caused by drag racing? Any Pontiac in reasonable Factory condition, or equivalent, can make many 1/4 mile passes with no damage to the drive train, other than some accelerated wear on the tires, providing the following conditions are met or observed.

The car is driven intelligently – no neutral “drops”, no rolling backward and shifting to drive.
The engine is not run at a high RPM while doing “burnouts”. Don’t come out of the water at high RPM and let the tires hook up on dry surface.
A reasonable RPM limit is observed at all times. The factory red line or lower is a good starting point.
Try to keep the drive train slightly loaded, or tight at all times. This is impossible to do with manual transmissions, but in that case, shift carefully and let off the accelerator between shifts. Also, operate the clutch smoothly and don’t slide your foot off sideways. The idea is to minimize drive line snap, or unloading and quickly loading the drive train in all vehicles.
Assure your hood latches correctly and securely, and keep a window open slightly on a convertible to prevent top ballooning.
Note that none of the above cautions prevent you from running your car hard. There is a tremendous difference in driving hard and driving stupidly!

You must get your car ready During normal driving, and some full throttle spurts on a safe road, observe the following:

Does your engine overheat fairly quickly at a stoplight, or while waiting in line at the drive-in? If it does, you can be absolutely certain that it will overheat at the drag strip. Don’t risk embarrassment or possible damage to your engine. Correct the problem!
Does the engine stumble or bog when driving away from idle, or when the secondary of the four barrel or 3-2's are opened? The initial acceleration from a dead stop has a major effect on the elapsed time and any kind of stumble or hesitation will destroy any chance of good ET’s.
Does the engine cut out at the upper RPM range of any gear? This generally indicates inadequate gas supply to the carte., and fuel lines, filters, float level, and even fuel pumps should be suspected. If you are not sure of the condition of the air filter, replace it. Standard dry filters will provide the same performance as the highly advertised and overly expensive specialty air filters.
Does the transmission shift cleanly under full throttle? It does not need to shift hard enough to rattle the windows, but any slippage or engine run-up during shifts indicates possible clutch slippage. Accelerated transmission wear will occur under these conditions, so don’t race until it is corrected. Assure that the kick-down switch is connected and operating. In addition to accessing a lower gear and/or holding the transmission in gear longer, the kick-down switch also increases oil pressure within the transmission. The increased oil pressure causes a firmer shift with less potential slippage of clutches.
Does your car have loose or badly worn u-joints, or a very noisy rear axle? Don’t risk them at the strip. Repair as necessary, or identify the source of noise to assure that hard driving won’t cause breakage.
Check the normal tune up items: timing, spark plugs, filters, all fluid levels. Replace the old gas that has been in the tank all winter. Fresh quality gas will make a major difference. Will race gas help? Probably not. Octane level adequate for your combination will provide optimum performance and higher octane will provide absolutely no gain in performance.
All strips require a radiator overflow can to prevent water spills on the track. If your car does not have an overflow tank, obtain a plastic quart oil bottle and temporarily mount it with a plastic tie such that the overflow hose fits in the container. Most tracks also require a helmet that meets the “Snell 85? safety criteria. Some tracks have loaner helmets, but if you want to race regularly, buy your own. Most tracks require a drive shaft loop if you run racing slicks. The helmet and loop requirements may be waived at some club or show car races, but check to make sure before attending

Remember, drag racing should be fun and not a way of settling a grudge You will find out how your car runs, and if you prepare it as suggested above, it will run much better in your car’s performance against the rigged tests reported in most older magazines. Most had cheater engines, and/or happy clocks! Most stock GTO’s actually ran in the range of 14 60 to 15.50 from the factory. Some of the HiPo GTO’s were quicker, but very few ran quicker than 13 90 Most full size performance Pontiacs ran in the range of 15 – 15 40 I was there, and both drove performance Pontiacs, and raced against them

http://www.dapa.org/drag-racing-with-jim-hand-part-4-preparing-for-that-first-trip-to-the-drag-strip/#more-195

 
When The Flag Drops,,,



The Bull Chit Stops,,,


P. Engineer, Engine Builder

Drag Racing with Jim Hand – Part 5: Basic Techniques of Bracket Racing
March 16th, 2010 By Jim Hand

You will recall that pure drag racing consists of racing two cars from a dead stop to some given distance, typically 1/ 4 or 1/8 mile. The car that crosses the finish line first is the winner. Bracket racing consists of the same type of track and starting systems, but racing vehicles are grouped by their elapsed time (ET) potential, and raced against each other using a pre-selected dial-in. Two competing cars from the same bracket are paired, and the starting lights are staggered such that the slower car’s starting lights begin the sequence first by the difference of the two dial-ins. The winner is the car that reaches the finish line first, providing it did not run quicker than it’s dial. If both cars ran quicker than their respective dials, the car that ran the closest to its dial is the winner. Note that MPH has not been mentioned as a direct factor in winning or losing, and we will discuss that later.

To be a consistent winner in Bracket racing, your car must be able to run close to the selected dial each run. (It is permissible to change your dial after each run!) Additionally, your reaction time (time from the green light switch closure until your front wheel leaves the starting line) must be reasonably quick and consistent. In non-electronics classes where you simply drive with the car’s normal brakes and throttle, a relatively good reaction time (RT) would range from .520 to .560, and a consistent car would repeat to within .02.-.03. seconds. These numbers vary widely, and numbers outside these ranges can and do win many bracket races. However, these numbers will make you competitive in most non-electronic classes.

You must realize that reaction time is a key element in drag racing. For example, if two cars run exactly the same ET but one driver has a .600 RT and the other driver has a .700 RT, the first driver will win by .1 second. What does .1 second translate to in distance? If the cars in question can run 95 MPH at the finish, .1 second is equal to about 14', or almost one car length. Looking at another example, if your car runs .2 second quicker than the competitor, but you have a .800 RT to your competitor’s .550 RT, he/she will win by .05 second.

The elapsed time at the reaction time will always have this direct relationship, and both must be considered when reviewing your time tickets and/or your performance! How do you improve your RT? You must develop a consistent routine or staging your car, and stage identically each time. Remember, we recommend that you stop when the second stage light lights. Most tracks have a “courtesy” staging routine where both cars must turn the first stage light on before rolling into the second light. This prevents one car from trying to “burn down” the opponent by delaying staging. When both cars have the first light on, slowly advance until the second light just lights and then stop. This technique will position your car at the same location from the starting line on each run. Carefully watch each of the .5 second yellow lights, and “leave” at the same light sequence on each run. Typically, most cars can actually leave when the third yellow begins to glow.

If, after several runs and your RT is still not good, try leaving on the second light. If this causes a red light (foul), you will then know about when you have to leave in the light sequence to obtain reasonably good RT’s without fouling. An added advantage of barely lighting the second light is that your car actually has a rolling start from behind the actual starting line, and this provides quicker ET’s. My wagon will slow by .1 to .15 if it rolls further into the lights. Regardless of how you stage, you must do the same each time, and then adjust the time you actually leave to obtain the desirable range of RT’s.

The other important element of bracket racing is the dial-in. Experienced bracket racers have different methods of racing by selecting dials either slower than the car can actually run (sometimes called sand bagging) and then trying to stay slightly ahead of the other car, or dialing as close as the car will actually run. I strongly suggest you begin by selecting a dial that will allow you to run full throttle for the entire race without going too quick and “breaking out”. That is much easier said than done, but make your practice runs without changing anything on the car. Note the range of ET’s. Has the wind changed? Has it cooled off? Was your car hot on one run and cool on another? If your last run prior to elimination’s was the quickest, you probably should dial close to that ET. Otherwise, dial about the average of your two or three best runs. During elimination’s, if it is obvious that you are going to cross the finish line first, slow down by lifting from the throttle, or even tapping the brakes. Never run quicker than needed, and you will be less likely to “breakout”. Do not dial quicker than you can run to be “safe” from break-out. If you give your opponent a .1 second head start by dialing safe, you have given him/her about one car length advantage before the race even begins! If, during the race, it is obvious that the other car will cross the finish line before you, slow down by lifting or tapping the brakes prior to the finish line. This assures you will not break-out, and if your competitor runs too quickly, you will win. Caution! Braking must be done carefully and reasonably to prevent any possible loss of control. Additionally, many tracks will disqualify a driver for excessive or dangerous use of brakes. When there is an uneven number of cars in a class, one car will make a single run, called a “bye”. Always run full out on a bye in order to get a correct dial-in for the next round. Most tracks allow a break-out or even a red light on bye runs, providing you cross the finish line.

You should view each competitor the same. Do not change your routine for a very slow competitor, the best driver, or the quickest car. Simply determine who will leave first, and then run your race. Here is some advice that I received many years ago during my early attempts at drag racing. “In order to win a class, you must be able to beat all competitors, so don’t hesitate. When your class is called, be the first one up, and challenge the other drivers to beat you!” Remember that in drag racing, as in all sports, there are many good competitors, and it is virtually impossible to consistently beat them all!

http://www.dapa.org/drag-racing-with-jim-hand-part-5-basic-techniques-of-bracket-racing/#more-193

 
When The Flag Drops,,,



The Bull Chit Stops,,,


P. Engineer, Engine Builder