Hey guys! Im new here. I know almost nothing aboit engine's and even less about pontiac engine's. My brother in law gave me a 1973 firedird rust bucket I mean bad rusted like bondo around the windows and in the floor pan. Thats why he gave it to me. About the only usable thing is the front clip. So im building a new dirt track car out of it. My questions have to do with the engine its a 1973 350 with #46 heads. If the bottom end is in good enough shape I would like to use it. The rules are a 450 lift cam max, 500 CFM carb can run aluminum intake and in the frame headers. Question one is what numbers could I expect from this engine would the heads need screw in studs? how much can they be shaved With out the vlaves hitting the block? I plan to run and saginaw 3speed. What would be a good flywheel clutch combo. Needs to be stock. Im still up in the air about what to do. I know more about SBCs and thats what everyone runs so parts would be way easy to find and cheaper to get, but I think it would be pretty cool to run the ole pontiac if it could make the power to compete with this set up. Thanks in advance for any and all info.
Well, it just so happens that you have come to the right place. I have quite a bit of history with dirt trackin Pontiac motors.I'll start with this. You can build a competitive car with a 350P motor. However it will cost considerably more to do so than with a sbc motor. There are two reasons for that. #1 is that sbc parts are so much cheaper. #2 is that very few people know how to build a 350P engine for hi performance. One of my best Pontiac friends won lots of races and several track championships running Pontiac motors.Now, the 1st thing that you MUST do is study the rules for your particular class. Then you have to build your entire car as close to the max the rules allow for that class as possible. Now, that is IF you wanna be competitive. You can still have fun just makin laps. But it takes a lot more to run up front. So you need to decide how serious you wanna get with this build and exactly how much you can spend on it.Hey, think it over and if you wanna try to build a competitive car let us know. Also please provide a link to the rules for your class. If there is no link, then post the details of the rules.
hello;as mentioned, we need the rules.throw away those pos heads and get some smaller chamber heads.you need to whack off around 1/4" from their surface to make any compression with those, lol.you can also get custom domed pistons instead if they allow it but other heads might flow better anyway
The just of the rules it that the car must be stock 3400lbs. We can use after maket springs. Everything must be in the stock location like shocks springs control arms. The car it self I can do no problem. Ive been around dirt track my whole life and been helping my buddy for the last 6or so years in street stock open wheel and now crate late model. He has been doing this a very long time. I helped him build 3 street stocks. Won multiple races for us and other teams. This will be my first car. Ive already got it stripped sub frame tied in x braced and starting the cage. The engine rule is pretty much what I have above its a pretty simple class. (Pure stock) I suck at links and tech. Stuff on this phone so I cant post them. But I plan to keep this car on our home track whynotmotorsportspark.com I think that the website. Its in meridian Ms.
In short the engine rules are stock crank and rods, dish or flat top pistons only. 450 max lift cam solid or hydro. No roller cams. Stock cast iron heads can run dual plain aluminum intake and in the frame headers. With 500 CFM carb.
hello'ok you can get some light weight je flat top pistons and some ram air heads and mill them to get your compression up for the gas you are using.0 deck your block.get a holley 500 cfm race carb.i would run a 3 finger pressure plate mcleod around 2400 lb.mcleod dual friction or racing disc.possibly aluminum flywheelsolid lifter custom ground cam.full roller scorpion "endurance" style rockers or similar.titanium spring retainers.oil restriction mods.
OK, here's my 1st observations about the rules shown for your track. It may be better to run a 406 Pontiac motor @ 9 pounds per cube. Here's why. The Bird will be quite nose heavy. As you know, the larger % of weight you can get on the rear wheels, the more bite you'll have off the turns. So you can add the extra weight to the left rear of the car. This will allow the extra low end torque of the 400 to out pull the 350 sbc motors off the turns. I watched my Pontiac friend do this lap after lap. He set up his Bird to hug the inside of the turns, then out pulled the Chevys off the turn. By the time they caught up. It was time to turn left again. And they were turning close to 8000rpm. He was only turning 6500rpm.I don't know what HP the sbc motors in your class are making, but a max built 406 Pontiac, legal for your track rules will make close to 500hp with a good 4bl. So that means that the carb is ABSOLUTELY CRITICAL in determining total power output. If you have been around racing as long as you say, you already know this. An absolutely box stock 4412 Holley will NOT be competitive at all !!! Your rules state that they will check the bore size. But if your track is like all the tracks in this area, the tech guys will not take your carb off an take it apart to see if it is still box stock.There are guys all around the country who have come up with every possible mod that will increase performance and yet appear "stock". The guys who run up front have plenty of $$$ to buy the latest and best legal carb available. If you don't know how to locate one of these carbs, you may check with some guy who has been a front runner in your class, but is now moving up to a higher class. He MAY sell you his old carb, if he's a guy you can trust to sell you his GOOD carb and not something else. I've gone into great detail about the carb, because it is the choke point of power.Another advantage of using a 400P instead of a 350P is that good, light, forged pistons are readily available. The lighter the pistons, the quicker the motor will rev. There are 5140 forged rods that will pass for stockers if the tech guys should ever take a peek at 'em. That's the good news. The bad news is that the rods and pistons will cost about $750. http://www.competitionproducts.com/5140-I-Beam-Rods-Pontiac-6625-Press-Pin/productinfo/4556/#.U3473tJdVZ4http://www.summitracing.com/parts/wis-pt048a35/overview/make/pontiachttp://www.summitracing.com/parts/pbp-14473-030/overview/make/pontiacOne more advantage is that the larger bore of the 400P will unshroud the larger 2.11 intake valves much more than on a 350. The tops of the cylinders must be chamfered quite a bit on the 350P to unshroud the 2.11 valves. This can easily be seen on the '69 350HO engine.Also, for racing, the best mechanical pump is a RobbMc. And they're not cheap either. http://www.robbmcperformance.com/products/pontiac550.htmlSince the Bert and Brinn trannys are legal, anything else will rob power and weigh more. If you use one, that will take care of your clutch question.Well, I'll leave it there for now. You can be competitive with a Pontiac engine, but it will cost much more than a Chevy. And you can do it with a 350P block, but that will cost even more than with a 400P block.
From bigD"An absolutely box stock 4412 Holley will NOT be competitive at all !!! Your rules state that they will check the bore size. But if your track is like all the tracks in this area, the tech guys will not take your carb off an take it apart to see if it is still box stock."There are guys all around the country who have come up with every possible mod that will increase performance and yet appear "stock"."The phrase "appears stock" and "the tech guys will not take it apart to see if it's stock" both STRONGLY implys that theses carbs are NOT stock and were therefore intentionally modified to circumvent the rules.If this is the case, it is called cheating, plain and simple.I was a professional racer and I never once cheated. if you have to be a Lance Armstrong to win I don't want anything to do with it.I doubt anyone here would condone or do this either and will not be impressed by this implication.If one wants to know how to circumvent the rules or be on a forum that talks about how to do it, I'm sure there might be other ones that are more better suited for this than this one.
Heath, if you doubt that anything I've said here is true, I'll be happy to put you in touch with my Pontiac friend who has built and raced Pontiac and Chevy motors in several classes, at most of the tracks that have come and gone in this area for nearly 30 years.As I stated, you can just make laps and have fun. But if you wanna run with the big dogs, then you must have equal equipment. Especially the carb. If your track lets the fast guys run a certain carb that runs better than box stock. Then you'll need a real similar carb to compete. YES it's that simple !!!My friend and his competitors used what they called an "890" 2-bl. It started life as a 650 Holley 2bl. But was modified by C&S, and others to flow nearly 900cfm.I'll post some links to some commercial dirt track carb suppliers for you to check out.http://www.candsspecialties.com/store/html/balflow1.htmlhttp://vdlfuelsystems.com/?p=76http://www.thedirtforum.com/2barreloval.htmhttp://www.speedwaymotors.com/Willys-Carbs-WCD44120-500-CFM-2-Barrel-Racing-Carburetor,7397.htmlhttp://www.smicarburetor.com/products/sfID1/7/sfID2/48/sfID3/16/productID/1http://jdrperformance.com/2-bbl-carbs/jdr-4412-gas-carburetorshttp://www.chucknuytten.com/carburetors/Circle/ct.htmlhttp://www.prosystemsracing.com/weapon4412.htmlhttp://www.bakercarb.com/productsservices/2barrelcarburetors.htmlhttp://www.ebay.com/itm/QFT-500-CFM-4412-CIRCLE-TRACK-CARBURETOR-IMCA-SPORTSMAN-/200589889385?pt=Motors_Car_Truck_Parts_Accessories&hash=item2eb416cf69&vxp=mtrhttp://www.aedperformance.com/competition-carbs/circle-track/aed-competition-500-e-detailIn bracket racing, you can run any carb you choose. But in dirt racing, if you run a stone stock "out of the box" carb, you'll get lapped in every feature and most heat races. It's just a racing fact that most all dirt racers know. There may be some "Professional" hobby class racers out there somewhere. who run stock "out of the box" 4412 Holley carbs. But I have never seen one at any of the dozen or so local dirt tracks I went to. Then again you can still have fun, even when you get lapped. I did, several nights.
bigD:Heath, if you doubt that anything I've said here is true, I'll be happy to put you in touch with my Pontiac friend who has built and raced Pontiac and Chevy motors in several classes, at most of the tracks that have come and gone in this area for nearly 30 years.As I stated, you can just make laps and have fun. But if you wanna run with the big dogs, must have equal equipment. Especially the carb. If your track lets the fast guys run a certain carb that runs better than box stock. Then you'll need a real similar carb to compete. YES it's that simple !!!My friend and his competitors used what they called an "890" 2-bl. It started life as a 650 Holley 2bl. But was modified by C&S, and others to flow nearly 900cfm.I'll post some links to some commercial dirt track carb suppliers for you to check out.Rules are rules, it’s that simple. If a track does not conform to the rules, they either need to change the rules or announce to everyone that they do not enforce the rules and let everyone know what they can “get away with” so at least the playing field is known if one wants to go that way.If a track has rules and allows people to break the rules, it’s still called CHEATING. I don’t care what anyone says or how they try to rationalize it. CHEATERS always try to rationalize cheating, this is just what cheaters happen to do. This is what Lance Armstrong, Barry Bonds, Marion Jones, Carl Lewis, and a long list of others did. We all know that it is illegal for athletes to take steroids in most professional sports, but I don't think Barry Bonds coach, team, or owner was lookin very hard at the obvious, so just because his team might have tacitly condoned it, does that mean it was ok. If all the locals are allowed to cheat and a new guy comes to the track and does not know that he is allowed to cheat because the track does not have a sign that says your 500 cfm carb can flow 900 cfm because we don’t enforce the rules, I think that guy might be kinda pissed off.If someone has to cheat to "run with the big boys" which is what is clearly being implied here, I suggest you find a hobby that has at least some level of integrity to it, like perhaps, lawn bowling.
Heath, unless you can get special permission from the track owner, I don't think you can run a Pontiac motor in Pure Stock. (1) The rules call for a small block. Many tracks I've been to consider all Pontiac motors as big blocks.(2) The valve size is limited to 1.94 intake and 1.50 exhaust. The smallest size exhaust valves I am aware of that came in a 350P head is 1.66Now you can probably get by with these if the owner OK's 'em as long as you don't run up front or win any races. But believe me, if you beat a kid's Chevy, whose dad has put lots of $$ into his son's car, they'll stir up all the Chevy guys and force the owner to DQ the Pontiac. I've seen it happen. When my Pontiac friend 1st started racing, he ran a second radiator behind the seat, for extra cooling. There was no rule against it at this little track he was running. It was perfectly alright as long as he was running in the rear. But after he got the Bird hooked up, and started winning features and embarrassing the Chevy boys, they started looking for a way to get rid of him.Somebody spotted his extra radiator, so they had the owner make up a new rule against it. So, he just started racing at another track. Here's his 1st car which I bought after he built a 2nd gen.Most small tracks are very clannish. They don't take kindly to outsiders coming in and winning races. But since you have been going to this track for a while, maybe you are well enough known that you could get by with running a Pontiac. It would be interesting to ask the owner and see what he says. You definitely need to know before you spend any $ on a Pontiac. Please ask and let us know what he says. Also is anybody else at the track running a Pontiac motor ? My friend was usually the only Pontiac powered car at all the tracks he ran.Hey, he even built a Late Model with a Pontiac motor. He's still running the roller cam out of it in his '69 street Bird !
I've been lookin at the Pure Stock rules some more. If the owner will let you run a 350P then you can run some 72 cc heads from a 68, 69 or 70 2bl 350P. Or even better, some '68 350HO heads, which have smaller chambers. Then you can shave these down another .050 or a bit more to get the CR up to well above 10:1. These will work well since you can run racing gas.The rules appear to allow any flat top or dished aftermarket pistons. This is a very important part of a competitive engine. They need to be the lightest pistons you can buy that are strong enuff to live in CT conditions. This is THE most expensive part of a 350P motor. The cheapest high quality forged 350P pistons I have found are custom BRC brand. The absolute highest quality brand available, that I know about, is Ross brand. They will make 'em any way you want 'em with just the correct pin height so you will not need to cut any off the block deck, except just a clean up cut, to end up with the optimal zero deck height.These light pistons will allow the rotating assembly to rev quicker, and make more power. That's the good news. The bad news is that they are about $800 total, by the time they get to your place. I noticed that the rules say "cast iron intake only". But that's OK, cause the cast iron Q-jet intake will make more power than the Edlebrock Performer alum intake. I'm sure you know you can use an adapter to mate the 4412 Holley to the Q-jet intake.I noticed that you are allowed a 9" Ford rear end. This is definitely the way to go. It will allow any gear ratio you could possible want. The rules say no floating brakes. I don't know what those are, but if floating hubs are legal, that's definitely the best way to go. It will eliminate bent and broken axles. You need less gear with a Pontiac motor because they have a longer stroke. You need to max the rpm at the end of the straight out to no more than 6500 rpm. 6000 may be even better, depending on where the peak power is with the combo of cam and heads you run.You can have a custom cam ground with the max .450 lift that will make power to well over 6000 rpm. And with Rhoads lifters, that same cam will have more low end torque for coming off the turns. Yep, the 350P can be competitive IF they'll let you run it !!!
I'm lookin closer at the Pure Stock rules, I see that you can run a "602" crate motor. I looked up the specs on that motor. It has cast pistons and only 9:1 CR. It's recommended to turn it only 5500 rpm. Do many in this class run this motor ? If they'll let you run the 350P, it can easily be built to make more power than the "602" crate, and will have a LOT more low end torque off the turns. Plus, if I read the rules correctly, it can run forged lightweight pistons, which should out last the "602" cast pistons.The rules say the sbc can be a max of 362ci. But the max overbore for other engines is .060. So that's the best size for a 350P, since it has such a small stock bore. It says no strokers such as the 347 Ford. But with a 3.75 stroke the 350P won't need any more stroke.Now since the sbc motors are allowed Vortec heads, there should be no problem allowing 350P motors the earlier small valve heads. The best number is #18 which came on a '68 350HO. It has 64cc chambers in stock form, which is listed as 10.5 CR on the 350HO. It is shown to have 1.96 intake valves and 1.66 exhaust valves. If the head charts I'm lookin at are correct(they do not all agree), the next best head is the #46 off a '69 400 and 428. It has 68cc chambers and the 1.96/1.66 valves. There are lots of head charts online. Here are 3 I'm using for this post info.http://www.classicpontiac.org/FAQ.asp?myPage=V8HeadInfohttp://www.antiquecarparts.net/tech04.htmhttp://ronspontiacpage.com/reference-pages/stockheadspecs.htmThen there are at least 3 small valve heads listed at 72-75cc. These could be used with a healthy cut to increase comp. The numbers are #15 & #17 from '68, and #47 from '69. Now if the charts are correct, all these small valve heads have press-in studs. But screw-ins are allowed, so that needs to be part of the machine work done on the heads. It's best to install helicoils for BBC 7/16 studs.Then there is another possibility for the heads. There were some '65 thru '67 closed chamber heads, which seemed to run well on the 389's and 421's. And the 326 heads have really small chambers, which will increase comp even more. But I don't have any experience with these old closed chambered heads. So if some of you guys out there have, let us know if you think any of the following closed chambers will run better than the heads I've already mentioned, on a 350P dirt track motor. Keep in mind that there is absolutely no porting or polishing allowed in this Pure Stock class.One of the best might be the '67 326HO head #141. It's shown at 10.5 CR on the 326. The '66 #095 326 head is also shown as 10.5 CR. The '65 #22 326 head is listed at 60cc. They show to have 1.88 intake valves. But 1.94 or 1.96 could be installed during the head work. Then there are at least three other heads from '65-'66 listed at 68cc: #77, #093, & #094. The 1st two are shown to be 389 GTO or 421HO heads. The #094 is a 326 head. So, if the closed chamber heads are better for this app, then there are plenty to choose from. Not too many guys use the 326 motors. So there should be a few of them left to rob the heads off of.Sometimes these Pure stock type rules are mostly in the head of the tech guys, and do not necessarily match the written rules. So it helps if you are friends with the tech guys. This may not be fair, but I've seen it to be this way at most of the dirt tracks I've been to. It's just a fact of life. If you act nice, and don't cause any trouble, sometimes you can get by with stuff some of the bad boys can't. So this is a good tip: be nice at your home track. Don't argue and cause trouble. And be especially nice to the tech guys. This will usually play into your favor somewhere down the road. That advice won't cost you anything.
OK lets dig a little deeper in to the track rules. For any of you guys who haven't been keeping up with this thread so far. Heath was wanting to know if he could use the '73 350P engine to compete on his local dirt track. So, in order to answer that question, we have to examine the track rules. It seems that very few tracks have exactly the same rules. So you have look carefully at the details of the rules, before you spend the $ to build a motor that may not pass tech. In case you'd like to see these rules for yourself, here's a link to them.http://whynotmotorsportspark.com/Since this will be Heath's 1st car, he wants to start off in the Pure Stock class. So we've been lookin at his track rules for Pure Stock. Now for anybody who doesn't know much about dirt track racing, one thing you need to know is that most of the rules are written with the small block Chevy motor in mind. So, at many tracks, you really can't tell much about rules for a Pontiac motor. Some tracks won't even let a Pontiac motor run, saying that all Pontiac motors are "big blocks", including the 350P. But I've found that some track owners will let you run a Pontiac if you ask him nice. When asked about this a few years back, the owner of a local dirt track said something like "I don't have a problem with it." Hey, they wanna sell more tickets, especially pit passes.The reason I said all that is because I can't see a Pontiac motor included in these pure stock rules. But that don't mean the track owner won't allow it. So, we're trying to pick out the best combo of parts for a competitive Pontiac 350P motor which will conform to the rules of the class.In this post I want us to look closer at the carb rules. Of course, the carb must begin life as a Holley 4412 500cfm 2 barrel. The throats cannot be enlarged at all. The throttle shaft and blades, or "butterflies" cannot be altered. The choke tower cannot be milled off. The choke plate can be removed. The power valve may be removed/blocked off. The accelerator pump squirter may not extend into the area directly above the venturi. The rule says that this is for tech purposes. I assume that means so that it will be easy for the tech guys to measure the diameter of the throats, all the way to the butterflies, to make sure they have not been enlarged. The last sentence of the carb rule is "Recommend epoxying the boosters for safety. I've never heard of that before, so if somebody knows the purpose of it, please explain it here. Thanks.Now there are all sorts of little tricks that can be done to the carb so that it will make more power than a stock "out of the box" carb. It would take too much time for the tech guys to take each carb apart to find something that has been altered. So, to police up this area, there is a carb "claim rule" in effect. That is, the owner of any car in the feature race may "claim" the carb off any car that finishes ahead of his car in the feature race. To do this he must pay the guy $300 and give him the carb off his car. The rule says the tech guys will determine if the claimers carb is in good enuff condition to swap. Each claimer is only allowed two claims per season.So why would anybody wanna claim somebody else's carb ? Well, that's because the carbs with all the latest and best tricks done to 'em will produce more power and cost a LOT more than a box stock carb. Some of the best carbs will cost nearly $1000 or more. So if you pay $100 for a good used stock carb, then claim one of the $1000 carbs, you get the $1000 carb for a total investment of $400. So this rule is to discourage the high $ guys from buying the expensive carbs.Now, that's how it's supposed to work. But at the tracks I know about, the claim rule is not used. For example, I've known of tracks which had an engine claim rule. But he racers sort of agreed not to claim each others engines. Most of the guys who ran up front had so much money tied up in their motor, that if somebody claimed it they would just load up and go home, then start racing at some other track. And besides that, there would probably be a fight in the pits over it. So it's just sort of an unwritten rule amongst racers not to use the claim rule. But now that don't mean they won't protest another guys motor, and have the tech guys take a closer look at it.I remember a few years back when a guy borrowed a trick carb for a big race, and won the race. But the tech guys found the carb to be illegal, so the guy was DQ'd and didn't get a penny for the win. He said that he had borrowed the carb, and had been assured that it would pass tech. But it didn't, so the guy was not only DQ'd but also probably quite embarrassed when it was announced over the PA system that he had been DQ'd.So the carb deal is sort of a slippery slope. If you got a trick carb that will keep you at the front of the pack and pass tech, that's great. But if your trick carb don't pass tech, well that can't be much fun. So why even take a chance ? Well, as I mentioned in an earlier post, all the guys running up front will have a trick carb. So if you wanna run up front, you MUST have a carb that will produce as much power as the other guys have. That's just simply an unwritten law of dirt racin.
...it helps if you are friends with the tech guys. ...It's just a fact of life. If you act nice, and don't cause any trouble, sometimes you can get by with stuff some of the bad boys can't...Yeah...a $10.00 bill might help persuade them to let you cheat too!This may not be fair, but I've seen it to be this way at most of the dirt tracks I've been to. I think it's perfectly fair providing you don't get caught cheatin.So this is a good tip:Yes, suggesting that one cheat is ALWAYS a good tip!That advice won't cost you anything.Well hey...at least the price for the "good" advice is right.