Need help with this Pontiac 428 build..Where are the Pontiac gurus??

[holsey82979]

Hello to whoever reads this..I am building a 428 .30 over flat top piston with 6x-4 heads.I had 16's but the cr was too high causing detonation.I am using these heads and 1.52 roller tip rockers,rpm intake,headers 2 1/2 exhaust,pertronix hei,and a jet street master 750 quadrajet. need info on a good camshaft(heard you cant beat the 068),stock converter or stall,headers or RA manifold,gearing,timing recommendations,spark plugs,best oil to use,and whatever else your wisdom can offer from experience.If I can get anywhere near 400 horsepower im good.I need too get this thing right this time.Its all in a 71 lemans.
Thanks

[DanStokes]

You'll want input from Thumpin' 455 (Todd) on here - he Da Man on Pontiacs and especially on bang-for-the-buck builds. If he doesn't chime in I'd send him a PM - he's a great guy and VERY knowledgeable.

Dan

[G-Motive]

Engine theory is engine theory bro.

[Mater]

i am going to be following this as well as it;s relevant to my interests

[Barry Donovan]

Engine theory is engine theory bro.

pontiac is special.

I think they have freakish tall decks if I am not mistaken... long rods and something.
I'll follow too, I have nothing to say.

[V12guy]

The 428 (and 421) Pontiacs are said to be "Perfect" with their 4" stroke. Of course this is from the old "H-O racing" books which are cool, but REALLY dated now.
The "068" cam is a good cam, BUT it was made in 1968, with the technology of the time. I have the NEW(er) version of this old standard from Comp Cams, it works very well in my 1973 4 speed GTO. I do not recall the exact specs or part number, but give them a call, very helpful, and their cam won't be that much more than a replacement '068'.
Without knowing your budget, or the cars intended use, it is impossible to recommend gears or TQ stall info.

nose around at the "Performance years" site, they are all Pontiac, all the time there

[G-Motive]

You're moving backwards when you lower the compression. A decent set of aluminum heads should help with the detonation.

[Thumpin455]

The 428 will grunt almost like a 455, and spin like a 400, but keep it under 6000rpm. All you need is about 2200 stall, 2.73 to 3.42 gears, I like 3.08 best, and more than 3.55 will just waste the power you'll be making, along with the stall speed. Trust me on that, you aren't diving a chevy, you don't need more gear like a 350 mouse does. Headers be Ram Air manifolds, we'll that is mostly preference and how often do you want to tighten bolts. Speed guys can't get headers to not leak, I figured it out years ago, but either will work about the same performance wise. You can go with the cheap $135 Summit headers and they fit good and run well, or you can go crazy with headers or manifolds. The manifolds cost more but last longer, they're also heavier. Both will work fine, so up to you really.

Now the cam. First thing get CompCams #995 Springs for the heads, they're $100 or so. No valve float before the rods fly out. The cam has some leeway, and the duration at 0.050 lift is what is important. With unported heads stay under 234 duration at 050, it only moves your rpm range up. A 2200 stall will work with cams into the 240 range. You want a 110 to 112 lobe center and don't worry about the lift. The 068 is a nice mild cam. I'm running the Summit 2802 in the 400s powering my 68 LeMans and the 65 GTO, good middle of the road cam but get quality lifters and break it in right. They'll go flat easy if you screw it up. You want a cam about the same size, bigger will give you a more choppy idle. The cam Mater had in his Grand Am is a "small" torque making cam. 204/210 is little, relatively smooth idle, lots of vacuum.

Plugs? I like NGK and AC, do not use splitfire or anything special, basic plugs work best. Don't use platinum nor iridium plugs, no need. Oil is whatever you like. I like Rotella, Castrol, Mobil 1, and Valvoline. 10w30 will work.

These engines don't need anything exotic to run damn hard, they don't need rpm or big intakes. Forged rods and a cam swap on an otherwise stock rebuild will make your 400hp easily. It's not a chevy, the factory intakes work great, all the d port heads flow roughly the same with the same size valves, and building it worth common chevy thinking will result in a slow car. Common chevy thinking is more gear, more stall, more rpm. The great thing about a Pontiac is that you can run a highway hear and still run 11s with out.

[holsey82979]

It has some camshaft in it that is supposed to bleed off some compression.The motor was built and had detonation and tore back down to install it..This is my first Pontiac build.It doesn't ping at low rpm or when the timing is way low just under heavy stress.I found out that 9.5 to 1 is max cr on 93 octane in a Pontiac. Car will be a daily driver sometimes so i need everything to be very streetable. I bought a pair of 6x-4 heads to lower cr and need to set up the rest to make up for the loss of compression.I was told to try a cometic head gasket to lower the cr from Butler and they do have one to get around 9.5 to 1.I am open to any suggestions (other than aluminum heads) as the 6x heads can easily be sold and I just diddnt want to pass them by. Dont know anything about re curving a distributor as i hear this may stop it with the high compression #16 heads.Hoping i get good info on what to buy for a budget build.

[Deaf Bob]

Holsey, you were just told how to do it reliably by Thumpin...
He is cheap.. Gets good results..
Not gonna do better than what he just told you without spending wheelbarrows of greenbacks..

[Mater]

so basically what thumpin said i already have done do the engine in the GA. except my stall is a bit higher at 2400

sweet score on my part.

[Thumpin455]

Unless you drop the compression to below 8:1, you won't notice much difference. Now if it had 11:1 or higher and needed race gas, then you'd notice. If you want more power, and those 6X heads to Butler for a street port. They do it by hand so it would take a couple months. You can send them to Kaufman racing for a CNC port too, they have info on the site as to how much. SD up in Canada does CNC porting too, and they do s great job. Runs $1500 for porting and complete rebuild, new valves, Springs, guides, etc. CNC is faster and very accurate so the flow is consistent.

Stay the hell away from Fulper and his Rock n Roll bullshit, dude is a loudmouthed crook. Known about that guy for two decades now, he hasn't improved and he screwed more than a few of my friends. I'm thankful he was a jerk to me on the phone and demanded a credit card number before he'd talk about my engine. Butler is great, Jim and I have become friends over the years, he's a Vietnam veteran so we get on great. But they do take a while on the porting. I get moist of my parts from them.

The other thing you can do leave the compression where it is, or raise the compression, and put it on E85. I did that with my 70 GTO and it's 455 is running 13:1. My 68 LeMans is running E85 too. The 65 LeMans has an 11:1 455 in it, so when I get it running it will run ethanol too. All it takes is a carb swap and you'll never worry about detonation again. DeafBob is running one of my conversions on his derby engine, ethanol is a wonderful fuel. E85 is avaliable all over Georgia so it's very easy to get, runs better than race gas and costs less than 87 octane camel whiz. It runs cool, makes tons of power, and your engine and fuel system parts will last longer despite what you hear about it. I'm a broke ass crippled Iraq veteran, I can't afford to run something that is bad for my car, and I can't afford to buy exotic parts, so I know the stock stuff works, mine are all original tanks and lines.

If you want to know about switching to the more power less expensive fuel, I can help you out.

[Mater]

e85 is wonderful performance fuel (crap for emissions i think do to having to burn more). ran it in my supercharged grand prix with an alcohol content sensor so it could pull timing and change injector pulse width if i put normal fuel in.

rarely did that just kept a 5 gallon can of e85 with me if i went out of town

[G-Motive]

I priced racing fuel the other day at the pumps & it was over 7 bucks a gallon,.....

Made me kinda glad I kept my compression down on the bird. I think I'm about 11 to 1 but she has no problems running on premium with the aluminum heads.

[G-Motive]

My 950 Holley sucks up gas like it's going out of style.