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10 Engine Wives‘ Tales - Debunked

  
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10 Engine Wives‘ Tales - Debunked

 
Pontiacman8 Pontiacman8
Moderator | Posts: 5777 | Joined: 02/08
Posted: 01/03/14
06:29 PM

1.) Grinding a crank under makes it weaker – Cranks always break in the same place, the radius – it’s the weakest part of the crank. The larger the radius, the stronger the crank. When a crank is ground there’s actually an opportunity to increase the radius and thus increase the strength of the crank. It’s all in the hands of the person doing the grinding – choose him or her Smile wisely.

2.) Fuel Injection always makes more power – Fuel injection does a great job when throttle position changes often. For types of racing where the throttle is wide open most of the time (i.e. drag racing), a carburetor is a formidable opponent – especially when matched against throttle body injection.

3.) Too much spring pressure is hard on valves – What’s hard on valves is the speed at which they contact the valve seat at closing. What dictates how hard the valve hits the seat? It’s supposed to be the camshaft closing ramp, but when spring pressure is too low the valve does not follow it’s intended path and instead slams into the seat and actually bounces. So, actually more spring pressure helps the valve by forcing it to more closely follow the cam shape.

4.) Rod bolts break because they’re bad – Rod bolts are falsely accused of engine failure more often than any other part in the engine. 99% of the time a rod bolt breaks it’s not the bolt's fault, it’s the engine builder's fault – more directly the one who torqued the rod bolts. Not surprisingly, I’ve had a hard time getting people to agree – it’s a lot easier to say and believe that “It’s not my fault.” Rod bolts work by stretching, usually around .006”. They’re almost always less (say .004) when torqued with just a torque wrench. A stretch gauge is the only way to go.

5.) A 10qt oil pan needs 10 qts – Your engine needs only enough oil so the oil pump pick-up never gets uncovered, not an ounce more. I think you’d be surprised how little an engine can run on – I’ve raced with three before and heard rumors of racers successfully using even less. If pan manufacturers would stop “rating” their pans this way, the confusion would eventually end. Most wet-sump engines are perfectly safe at five quarts.

6.) Head gaskets can’t be reused – Motivated by the cost of current racing head gaskets, I started reusing them. The shorter the engine run time, the better your chances of success. Buy one set of gaskets, use them when honing with torque plates, reuse them for mock up, reuse them for assembly and reuse them after tech teardown. The biggest risk is a water leak – if that portion of the gasket looks good, go for it.

7.) Glowing headers mean the engine is lean – This wives’ tale is starting to lose steam, but still believed more often than not. Headers glow red for only one reason, there’s fuel burning inside. The two main reasons are a rich mixture and late ignition timing - which doesn’t give the fuel enough time to burn inside the combustion chamber. Test it for yourself, let your engine idle and crank the ignition timing back to the point where it barely runs, then get out the marshmallows.

8.) Bigger cam and ports = more max power – I know that most people now understand that bigger is not always better, but there’s still a great many people who think that bigger always means more peak power. Well, this isn’t true either, too big a cam or ports can lead to reduced cylinder filling, which in turn leads to LESS max power. Remember, everything in moderation.

9.) Setting ignition timing by ear works – There are still some old-schoolers left that believe this one, and you can’t tell them otherwise. Someone setting ignition timing by ear will always end up setting the timing too high – at idle it sounds great at 60 BTDC, at 7000 RPM (under load) I’m sure it’s down right scary.

10.) Flick ashes in the oil pan for good luck – Now this is a real wives’ tale. Believe it or not, people actually do this – I’ve seen it. If your engine builder thinks he needs some good luck, maybe you need a new engine builder.  
Engine builder,self taught auto body guy.
Horsepower sells engines and torque wins races

Pontiacman8
Pontiacman8
Pontiacman8

tuffnuff tuffnuff
Moderator | Posts: 2567 | Joined: 12/09
Posted: 01/03/14
08:54 PM

+1
Nice post Pman.,. oh, is that cigar or cigarette ashes and any particular brand preferred.
I suppose if the engine builder is skeptical about his abilities, then a bit of luck and ashes might help the build hang together.
I bank on experience and developed skills aquired over the years, so my engines seldom grenade unexpectately.,. knock on wood,,,,, chuckles.

Smile  
When The Flag Drops.,.

tuffnuff

The Bull ***t Stops.,.
tuffnuff

P. Engineer, Engine Builder

4zpeed 4zpeed
Enthusiast | Posts: 368 | Joined: 04/13
Posted: 01/04/14
06:35 AM

+2 Pman,
LOL Tuff, Since I can't bank on my experience and well developed skills perhaps I should whip out ma wabbits feet and find summin to smoke. Where's that nice lookin lady offerin cigars and cigarettes, "Yes mam, I'll have a carton of each please."

Grin  
Poncho huggen gear snatchen posi piro.

dond1965 dond1965
User | Posts: 116 | Joined: 12/13
Posted: 01/04/14
11:34 AM

funny thing.... people cant see under the hood when they got their foot in it and the engine is burning lots of fuel, and thus producing lots of heat. but they can turn the rpms up with the car sitting and the hood up, and note the heat passing out the exhaust system. its pretty much common knowledge that leaner fuel mixtures raise exhaust temperatures, thus more heat through the pipe, the hotter the pipe. at least according to physics that is.  

dond1965 dond1965
User | Posts: 116 | Joined: 12/13
Posted: 01/04/14
11:56 AM

oh and the crank grinding thing..... you are in contradiction with the people who are gonzo about shared journal over lap. we'll see if any show up to school you on their theory.  

tuffnuff tuffnuff
Moderator | Posts: 2567 | Joined: 12/09
Posted: 01/04/14
07:41 PM

Hmmm, I don't believe that Pman needs to be schooled by you or for that matter, any other self proclaimed individual.,. it's a known fact that a liberal fillet radius on a crank, is preferred to an abrupt transition from journal to counterweight.
It appears you select to get cross threaded with anyone and everyone.,. why???

Smile  
When The Flag Drops.,.

tuffnuff

The Bull ***t Stops.,.
tuffnuff

P. Engineer, Engine Builder

dond1965 dond1965
User | Posts: 116 | Joined: 12/13
Posted: 01/04/14
08:23 PM

perhaps sir, you are reading into my statements what you wish them to mean, rather than what they plainly state? i did not state that I myself was going to SCHOOL any one. me thinks me smell a witch hunt!! but if memory serves correct you did have some commentary on my suggestion of using a 383 crank in a 283 block.... correct? peace tuffy, i aint lookin for trouble. im just stating my opinion like every one else.  

shyrgfuh3 shyrgfuh3
Enthusiast | Posts: 475 | Joined: 11/13
Posted: 01/04/14
08:33 PM

dond

"oh and the crank grinding thing..... you are in contradiction with the people who are gonzo about shared journal over lap."


People used to be gonzo in the belief that the world was flat too, so much so that the church punished Galileo severely for saying it was round years after Aristotle suggested it was.


Yes, it is a fact that grinding a crank will reduce the amount of journal overlap and subsequently reduce its strength to some degree, however, as shown below the amount the overlap is reduced by is not significant enough in and of itself to cause a crank to break, so in that regard, without pman going into a lengthy detailed explanation of this particular comment he made, imo, it is for all intents and purposes accurate.

I also think the overlap is a reasonable thing to bring up in general, because it gives people more info however using this logic, it would seem reasonable to me that one could also say that boring an engine out by .010” will reduce the cylinders strength. This is an absolute fact, but does it mean that it will instantly crack under load?... No, so what would be the point of mentioning it.

Pman is not saying that your crank will not be significantly more susceptible to failure if you grind 1/2” an inch off it.

The engineers designed the cranks the way they did for a reason. They were well aware of the effects of overlap.

In general, parts “used to be” designed with strength slightly greater than necessary in part to account for slight errors and/or unforeseen circumstances etc.

If this was not the case, then grinding a crank 10/10 would cause it to instantly grenade when put into service.

A 350 Chev has .535 overlap.

If one grinds both the crank and rod journals by .030” the overlap is reduced by .030”. This is a 2.803% reduction of the amount of overlap.

This percentage is less than the amount of “overbuild” in the strength of the crank and therefore too little to increase its potential for failure by a significant amount.



dond

"we'll see if any show up to school you on their theory."

Ok, schools over now.  

tuffnuff tuffnuff
Moderator | Posts: 2567 | Joined: 12/09
Posted: 01/04/14
09:14 PM

Icon Quotedond1965:
perhaps sir, you are reading into my statements what you wish them to mean, rather than what they plainly state? i did not state that I myself was going to SCHOOL any one. me thinks me smell a witch hunt!! but if memory serves correct you did have some commentary on my suggestion of using a 383 crank in a 283 block.... correct? peace tuffy, i aint lookin for trouble. im just stating my opinion like every one else.

I hardly think so dond, because when I get PM's about your behavior and critcism.,. I have to examine the origin of concern.
You did write "you are in contradiction with the people who are gonzo about shared journal over lap".,. so who exactly is "you" in your post, if not Pman.
Furthermore, there is no such thing as a 383 crank, but rather a 400 SB crank with turned down main journals to 350 dimensions.,. good luck stuffing a 3.75" stroke crank in a block designed and clearanced for a 3.00" stroke engine.,. show me how/where this is done successfully, without costing mega bucks.
I suggest you refrain from splitting hairs and cease flaming poster/setting them up as village idiots and complete fools.,. which they are not.
I've gotten PM's from annoyed members, voicing their concerns and I'm obligated to view the posts mentioned therein.
There is no witch hunt on this or any other site, where I Moderate.,. we as a community need to get along and use sensible tact, so we might all play well together without kicking sand in anyone's face, out of spite.
I validate your opinion, however I question your text and arrangement of words.,. please proof read your comments, before hitting the send button.
This post is not a warning but it is a caution to ease up on elbowing your way to the front of the class.,. it causes a disturbance that noone wants or needs.
We are in a sense bench racing and opinions vary.,. at times we defend our posture with too much enthusiasm and above all, we need to be prepared to be corrected, at times.
My function here is to maintain balance and with years of experience as my frame of reference, I take my position as neutral and without malice.
Peace.

Smile  
When The Flag Drops.,.

tuffnuff

The Bull ***t Stops.,.
tuffnuff

P. Engineer, Engine Builder

dond1965 dond1965
User | Posts: 116 | Joined: 12/13
Posted: 01/04/14
09:19 PM

perhaps sir YOU also have read into my comment what YOU wish it to say, rather than what it simply states? i did NOT offer an opinion as to what happens when you reduce journal diameter or pin shared overlap, now did i? but let me guess, by being plain spoken im CROSSTHREADING again? may i offer a little back ground? back in the late 70's ol bruce crower used to contribute to hot rod mag at the back. he stated he thought it was foolish to use a 2.45 main pin with strokes over 3.5" in the sb chevy. later when people started chasing their tails with reduced pin diameters in search of reduced friction, further testing revealed that crank flex in fact was increasing friction. im an old man. ive been a student of the internal combuster for over 40 years. i no longer waste my time arguing with people. if i feel i can help some one i will try to the best of my ability. i dont care who gets butt hurt or doesnt like it. as the kids say... it is what it is. peace.  

dond1965 dond1965
User | Posts: 116 | Joined: 12/13
Posted: 01/04/14
09:32 PM

the after market in fact produce 3.75" stroke 2.45 main pin cranks, most commonly used in 30 over bored 350 blocks. this combo as you know is a 383. that IS the crank i referred to. i do in fact know how they used to do it in the old days. and yes the YOU reference was pman. i never said he was wrong, now did i. i made a simple enough statement.  

tuffnuff tuffnuff
Moderator | Posts: 2567 | Joined: 12/09
Posted: 01/04/14
10:00 PM

No, I did not read anything into your post, other than what you put in plain print.
Unless the English language has lost it's meaning, it simply means what you stated and others tripped over it.,. which caused me to offer a few suggestions to clear the air.
Let's simply say that a lot of water has gone over the dam and it's time to move on.,. in good spirit.
I can't agree with your final comment because you should be concerned about how the whole of the community sees you and feels about your "multi meaning" comments.
Saying what you mean and meaning what you say should not send shock waves on this forum.
You can be plain spoken yes, but outspoken/cutting no.
Peace to you too.

Smile  
When The Flag Drops.,.

tuffnuff

The Bull ***t Stops.,.
tuffnuff

P. Engineer, Engine Builder

dond1965 dond1965
User | Posts: 116 | Joined: 12/13
Posted: 01/04/14
11:28 PM

perhaps i may be able to offer a solution to those who dont get me? go on thinking im a steaming pile of dog crap [and yes i KNOW people prefer bull crap to bluntness-and my cup runneth over with bluntness] but ask yourself ... how many times do you want to step in me? i have determined that a new tactic employed by me is best. if a post requests aid i will make a single recommendation and avoid ALL conversation. i get what i want [to aid the needy] and yall get what you want, the oppertunity to prove me wrong to appease yourself [with out me rebutting you-no matter how flawed your opinion may be]. so im not one of the good old boys, dont want to be, thats NOT why i come here. sound good enough?  

tuffnuff tuffnuff
Moderator | Posts: 2567 | Joined: 12/09
Posted: 01/05/14
12:08 AM

Very well, agreement creation is better than conflict resolution.
Let peace prevail and return this thread back to the original poster.,. because by now we are going over well plowed ground.
This is Pontiacman's thread and it has sadly gone astray in an oblique direction from the original good intentions of helping and informing others.,. to expressing personal feelings, which we all rightfully have.
I posted "Forum Rules - Please Read!" so there would be a clear outline of what text is acceptable and what is not.  

http://forums.highperformancepontiac.com/70/9604371/the-general-discussion/forum-rules-please-read/#9604371

Smile  
When The Flag Drops.,.

tuffnuff

The Bull ***t Stops.,.
tuffnuff

P. Engineer, Engine Builder