I just recently bought a 1974 ventura. Factory 350 car. I was told by the last owner the car had a bad rebuild from the owner before him. I took the top end of the engine apart to check everything. I actually found at some time in the past, someone put a 4 barrel carb on it. Also the heads are 094 1966 326 heads on a 1973 350 engine.  And the pistons are flattop pistons but they have some kind of dimple in the center of the pistons. My main question is, can these heads be a competitive set up? I do plan on drag racing the car. And I do want to use the 350 I have. But would I be better off finding the 71 350 heads? Any advice is greatly appreciated.  Use the 326 heads or change them?

 

 

 

 

 

 

 

 

Edited February 26, 20233 yr by 74ventura383

MY gawd.... NOWHERE does it say on the tube that you must use the Permatex all at one time.    Water jacket holes, pushrod tubes completely filled.....IT's even oozed into the cylinder. If that car was running, it would have burned that off.  The pic of the head.... how do you get it to squirt out of the freeze plug?    You had better plan on pulling the block outta there.  Who knows what your gonna find in the lower end.  Your pan N pickup are probably plugged with Permatex that made it to the oil pan.  Would contact Butler for rebuilding advise for racing.

https://butlerperformance.com/p-34888-pontiac-engine-torque-specs.html

Please keep the pic's coming on your progress.   Looks like your brake line is busted and I have no idea what tube is pinched off over the motor mount.

The level of abuse here would make Chief Pontiac cry!!!!

Edited February 26, 20233 yr by JUSTA6

Trust me I know. When I started goin further and further my mind was blown. I am pulling the engine out to go further. I Do have video of the engine running from the 2 owners ago who actually owned the car before the kid I bought it from. He was just as confused why the guy I got it from as to what he did because the guy who found me drove the car as a daily. So all of that was done by the kid I got it from. But I am going threw it and make it what it should.  I'm still hung up on the heads set up.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Best advice,  clean up lower end and check bearing tolerance. I would replace the oil pump, pull the timing cover and replace timing chain if needed, but expect to clean up a Permatex mess there too.  Then contact Butler for a price on heads, valvetrain needed, matching camshaft.  You have a 4bbl intake.  Butler might be your best bet on headers as well.  Build it basic, but bulletproof and enjoy many years of bracket racing.  Good Luck bro.   Please keep us up with picks on your project. Including some pics of both cars you have.

Yeah bro, welcome to the site. Good luck, it looks like you have a job ahead of you. Keep us posted on what else you find and your progress.

welcome !!

i am with the guys here, that motor needs some love !! 

JustA is sooo right pull it 

do a full rebuild, you wont regreat it !! 

AND you have to ask yourself whats my budget ! we all can drag race our toys... the question is ... what level do you want to play at !

 My thought has always been if i can get a nice streetable 350 hp out of a 350 ... thats plenty !! and fun too ! without being over the top and requiring a stronger trans, a stronger diff, bigger brakes, etc etc 

 justA my 

 

Here is a list from Wallace Racing of all the 350 heads Pontiac produced. You can bolt 326-455 heads on your 350. They will work but some of the more popular 389-421-400-455 (Ram Air and HO) heads are more desirable and than means the price goes up. 350 Pontiacs have sort of become the red headed step children of the Pontiac world. So I hope that means some of these heads are cheaper (assuming you can find them since 350s tend to get scrapped / ignored).

I would try to find the #18 or #48 heads first since they are the most HP per stock head. Then I might look for a set of 5c, 6X-4, or 6S heads since they have the larger intake and exhaust valves.

Edited February 28, 20233 yr by Frosty

You can search for any of these heads, but your dealing with 50yrs + equipment. Unless they are sold knowing they are already magnafluxed, crackfree base to work from.  You will still have to have the used heads done.  To deck, valve seals/guides, 3 angle cut and spring rates checked still has my jaw on the ground at what it cost me for the V6!!  That's why I'm suggesting he uses a Pontiac engine builder  (Butler)  You can have new heads set up anyway you want.  Hydraulic or roller and they can advise you about rockers/pushrods and cam for what he plans to do.  He can mention entry level set up (mild mods minimal cost to get you started)  with plans to up grade the go fast parts as you go along. They can recommend a valvetrain that could take a next size cam ect . Saving alot of $$ down the road.  Now you have a bulletproof setup to have fun with for years bracket racing.  He can learn alot justa talkin to the reps about different parts.

The biggest disadvantage of trying to make good power with a 350 Pontiac engine... Is the small bore size... The Small bores tend to shroud the flame and not allow the flame to swirl/spread in the combustion chambers as efficiently/completely...As it does in an engine with a larger bore and a shorter stroke...

Pontiac 350 engine = 3 7/8 inch bore...With a 3 3/4 inch stroke for a total of 354 (353.8) CID... The Small bore with the Long Stroke also limits the amount of RPMs that you can turn before the Piston Speed becomes an issue...Basically the 350 CID Pontiac is designed to make  good Low end Torque...Not high RPM horsepower...

For comparison a 350 CID Chevrolet engine has a 4.00 inch Bore with a 3.48 Stroke...(big bore..Short stroke)

350 CID Pontiac engine has a 3.875 inch bore with a 3.750  inch Stroke...(small bore..long stroke)

Even if you bore the Pontiac engine 0.60 over the bore will still be less than 4.00 inches...With the Long stroke...The Piston Speed Becomes a reliability issue...As the Piston itself has to travel significantly faster/further...Up and Down...Inside the bore at any given RPM Compared to an engine with a shorter stroke....At the same RPMs...

 

Edited March 2, 20233 yr by TWO LANE BLACK TOP

Good explanation and comparison Two Lane. Thanks, good read bro.

7 hours ago, TWO LANE BLACK TOP said:

The biggest disadvantage of trying to make good power with a 350 Pontiac engine... Is the small bore size... The Small bores tend to shroud the flame and not allow the flame to swirl/spread in the combustion chambers as efficiently/completely...As it does in an engine with a larger bore and a shorter stroke...

Pontiac 350 engine = 3 7/8 inch bore...With a 3 3/4 inch stroke for a total of 354 (353.8) CID... The Small bore with the Long Stroke also limits the amount of RPMs that you can turn before the Piston Speed becomes an issue...Basically the 350 CID Pontiac is designed to make  good Low end Torque...Not high RPM horsepower...

For comparison a 350 CID Chevrolet engine has a 4.00 inch Bore with a 3.48 Stroke...(big bore..Short stroke)

350 CID Pontiac engine has a 3.875 inch bore with a 3.750  inch Stroke...(small bore..long stroke)

Even if you bore the Pontiac engine 0.60 over the bore will still be less than 4.00 inches...With the Long stroke...The Piston Speed Becomes a reliability issue...As the Piston itself has to travel significantly faster/further...Up and Down...Inside the bore at any given RPM Compared to an engine with a shorter stroke....At the same RPMs...