So I listened to some of your request to live outside the box and ditched the 383 ideal. Now I'm gonna need mucho helpo. I picked up a 1970 400 w/ 1970 #16 heads. I've done a lot of asking around about machine shops w/ Pontiac experience and all roads seem to lead me to one shop that's family owned and has been in business for over 35yrs. I paid 300 for the motor w/o brackets or water pump and partial distributor. (good time to upgrade) Car doesn't have A/C or power steering so pretty much just need alternator bracket. First off since this motor was made the year after my mother was born and was discontinued before she graduated HS I know nothing about them. I have read more in the last couple weeks then I have my whole life. I also just ordered Jim Hand's book so I can read some more. I am going to take my block and crank to the machine shop Friday. As far as I can tell the bore is at 4.146 which is just under .030 over if I have read correctly. At first I thought it might be ware but all cylinders are at 4.146. I'm thinking they will just have to punch it out to the .030 mark there is a little rust on the walls but otherwise no gouges. Bearings were all good and crank seems to be stock and all journals good. I plan to scrap the rods for some forged as well as pistons. I would love to have some aluminum heads for this beast but 2000 is way out of the budget right now so I was thinking mild porting, 3 angle valve job, new stainless valves and springs. I guess my main questions to the experts is what questions do I need to ask the machine shop, are the small valve heads worth messing with or should I start jerking/bleeding in a cup for aluminum, and any other comments, ideals, suggestions, or anything you say will greatly be appreciated. O BTW it's all gonna be bundled into the 78 grand prix. Thanks for everyone's time, patience and knowledge.
OK poncho guys lend me your knowledge
- Thread starter Lumpy
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Getting Jim Hands book is a great start, he is a good guy to boot.
You can do real well with "stock" type stuff.
Stroker stuff is real attractive being you are planning on replacing the rods (good idea) anyway.
Tell me your true goals with the car.
Like any car/engine it's about the package.
FYI, I own a restoration shop that specializes in Pontiacs.
You can do real well with "stock" type stuff.
Stroker stuff is real attractive being you are planning on replacing the rods (good idea) anyway.
Tell me your true goals with the car.
Like any car/engine it's about the package.
FYI, I own a restoration shop that specializes in Pontiacs.
Not sure the valve size on your heads but I'd make sure you have the 2.11 intakes/1.77 exhausts. The smaller valve heads were usually used on 2 bbl setups. A few trips to the junk yard will probably find you plenty of choices of 6X heads. The 6X are pretty common and have 2.11 valves. The only downside is the 6X are low compression (I think 7.9:1). You could then either have them milled and bring it up to somewhere in the 9's:1 or keep searching for a 350 pontiac with 6X heads. The 350 6X have a higher c/r when bolted to a 400, however it wont have the screw in rocker studs like most Pontiac engines. Those can be upgraded to screw in studs pretty easily. There are several different versions of that head so just make sure to cc it.
There's several other heads that pontiac makes that are all very good for performance, I prefer the older 1960's heads with closed chamber and high compression ratio. Mine are 670's, off a GTO. Those require special attention for streetability, you have to keep the engine cool and back off the timing a little bit- or run race fuel. Luckily I have access to avgas which is 100 octane leaded fuel. The car loves it.
Are you going for mostly street use, or track only? Have you gotten cam ideas, roller/flat/hydraulic/solid/ etc.? I've always stuck with hydraulic since they're about zero maintenance and don't need adjustment like solid lifters. Also regarding streetability you usually have less vacuum with solid lifters, which means less power brake.
Do you have a budget or are you tryin to spend as little as possible? What power range are you aiming for? What gears and transmission setup is going with this engine? Do you have a carburetor yet/what size/style?
I've tried to stick to mostly stock parts, plus my low budget forced that to happen anyway... 8) Our car was consistently running low to mid 12's using factory parts, no special valve jobs, no special fuel pumps, stock HEI ignition, stock old used pistons and rods, fresh stock crank etc. In my opinion if your not aiming for 10 second 1/4 mile than you don't need tons of machine head work, or crazy high lift cams, or forged heavy pistons. That stuff all looks good in the magazine but week after week we were pissing people off at the track who had spent thousands of dollars on all the wrong parts.
There's several other heads that pontiac makes that are all very good for performance, I prefer the older 1960's heads with closed chamber and high compression ratio. Mine are 670's, off a GTO. Those require special attention for streetability, you have to keep the engine cool and back off the timing a little bit- or run race fuel. Luckily I have access to avgas which is 100 octane leaded fuel. The car loves it.
Are you going for mostly street use, or track only? Have you gotten cam ideas, roller/flat/hydraulic/solid/ etc.? I've always stuck with hydraulic since they're about zero maintenance and don't need adjustment like solid lifters. Also regarding streetability you usually have less vacuum with solid lifters, which means less power brake.
Do you have a budget or are you tryin to spend as little as possible? What power range are you aiming for? What gears and transmission setup is going with this engine? Do you have a carburetor yet/what size/style?
I've tried to stick to mostly stock parts, plus my low budget forced that to happen anyway... 8) Our car was consistently running low to mid 12's using factory parts, no special valve jobs, no special fuel pumps, stock HEI ignition, stock old used pistons and rods, fresh stock crank etc. In my opinion if your not aiming for 10 second 1/4 mile than you don't need tons of machine head work, or crazy high lift cams, or forged heavy pistons. That stuff all looks good in the magazine but week after week we were pissing people off at the track who had spent thousands of dollars on all the wrong parts.
My goal for the car is to get into the 10 second area with spray that's why I want forged pistons and rods. I would like to drive the car this summer and can probably put together around 2500 for the engine. I'm looking for a 400 bop transmission and am looking at running a 8.8 with around 3.73s. I am at the very beginning of a long journey.
Not to kill your plan, $2500 and 10 seconds is not going to happen.
May be able to pull off $2500 in parts.
I will see what other post before I go further.
May be able to pull off $2500 in parts.
I will see what other post before I go further.
Congragulations on sticking with Pontiac. That's all I've used for over 40 years now and I love em'. My only advice is to be honest about your intentions. A street motor that can live on pump piss is totally different from a 10sec race motor, so be aware of the tradeoffs. I would hate to see you be dissappointed with Pontiacs so listen to Shotgun and the others who race them, they won't steer you wrong.
I would eventually like to be in the tens someday. I would like to have a bottom end that I can build on to make a 10 second pass. 2500 is what I will be working with before summer is up. That is on the motor I know I also got to work on trans and rear as well.o
Maybe start off with a nice set of 6X or 4X low compression heads on that stout bottom end. 71' and 72' big valve low comp heads are great but lack the outermost exhaust bolt holes for some stupid reason. That way you have a solid buildable base and can upgrade later on. With the low comp heads you can enjoy the car and learn why Pontiacs are known as torque monsters. A stock 4 barrel manifold, mid-range cam, and well set up Q-jet will be an animal in a 78' GP. I had a 70' 400 with 6X heads and 278 cam in my 81' Malibu and it was extremely powerfull. Then once the car is together you can stockpile the go-fast goodies and go from there.
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