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pontiac 350

7K views 30 replies 4 participants last post by  robhardy 
#1 ·
ok,
i had no idea how hard it is to find a decent pontiac engine. the '70 455 ho was fried, bought a 76 that had been freshened that ended up having cracked heads and a block that i suspect is full of porosity.
long story short, i bought a 71 350 today. completely unassembled has been sitting for a couple of years.
the details are bored .40 over, 94 heads that appear to have had a valve job te same time the block was bored.
crank is 10/10 new pistons on stock rods, new power sealed cs-641 cam and lifters all in the box, new oil pump in the box, new timing set in the box, new bearings in the box.
i have a torker ii intake and a holley (probably 750) of of the 70. i also have the 64 heads from that engine that look pretty fresh (7/16 studs and roller rockers).
from the 76 i have a brand new lunati cam 07703 (too aggressive).
i want to combine what i've got for now and keep chasing a 400 or 455.
how much gain will i see by using the 64 heads vs the 94 heads? should gain c/r and between the roller rockers (i'll check but i'm betting they are 1.65's and the big valves i think the wimpy cam would be ok).
then add the torker ii and the holley along with ram air cast headers. i know there are some assumptions but if i'm right am i making 300 hp? 375+ pounds of torque?
i'm not planning on racing and the car will probably never see anything past 90 mph no matter what i put in it.
turbo 400 and i think 342 gears.
i've been so busy trying to get a running motor that i haven't really been looking that closely at some of what i have.
thanks for any input.
 
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#2 ·
The 94 heads would be what you want to run. The 64 are too big chamberwise. Compression would be to low.
My 64 has the same 350 in it you are talking about. It is a 71 350 with 94 heads.Runs OK. Has 2 barrel is probably stock.
I have a 389 that I have been trying to finish, and will this winter.
Pontiac engines are out there. Just need to look in the right place. I know where there is a 68 400 4bbl, and a 73 400 4bbl both good cores from a reputable guy.
The carb you have will be too big if it is a 750. A 600 would be closer to optimum. A quadrajet on a stock pontiac 4 barrel intake is a great combo...believe it or not.
one of the comp cams XE grinds might be a good cam choice. Maybe a Lunati VooDoo. Nothing wrong with a summit cam either.
Something like a 212/218 @.050 would be plenty for a 350.Dont go too big, especially on a 350.
 
#4 ·
You should CC the heads to see just exactly what the chamber size in for both. Its the only way to really know where your compression will be at. None of the head charts I looked at are consistent, nor have they been accurate in the past, some yes and some not.
I am guessing the 94s will be smaller chambers, as the 64 are from a 455 , which usually means larger chambers due to cylinder size.
 
#7 ·
Sounds like with what you have, you have most of what you need to build it. A cam wont be expensive, just pick the right one.
A pontiac intake and quadrajet wont break the bank, but you will need to look around to find a deal. Edelbrock performer is a good alternative intake, but i would opt for a quadrajet to put on top. Easy to work on and reliable.
CC those heads, so you can determine compression.
 
#8 ·
The 350 will need the heads with smaller valves.The bore size restricts the clearance between the cylinder wall and the valve, causing valve shrouding, basically impeding flow. if you look at the top of the cylinder bore of the 350, you will see 2 notches in the top of the bore.This is a relief or "chamfer" to help airflow around the valve as it is so close to the cylider wall that it wont allow good airflow in that area without it.
 
#10 ·
they are one year heads. 1970 455 h.o. they only went into grand prix's and gto's. rated at 365 hp in the goat and 370 in the grand prix.
the small valve issue solves that problem. i've got a 76 cast iron intake but i think mr. p-body told me it won't work on the older blocks but i'll double check that. there is cast iron intake for sale locally. i may slap an xe 256 in it and i'll definietely get a smaller carb.
my plan is to use that torker intake, the 64 head and the big carb on a 400. i'm just waiting for the right block to come along.
for now i want to drive this car while the weather is nice. that's why the 350 is going in for now.
i've had this car for a month and haven't been able to drive it.
 
#13 ·
carb is a street avenger 670 cfm. should be fine.
my only goal for this engine is a quick 0-60. the cam is 198 on the intake 212 on the exhaust with a lift of around 440 or somewhere.
going to have the heads re-surfaced and cc'd. the only question is whether or not the torker ii will destroy the low end torque.
i have a 76 stock intake. can that be modified to fit the 71 heads?
if that's not a cheap, simple mod and the torker ii will kill the motor off the line then a performer is probably the easy fix.
that cam probably plays out well before 5000 rpm's and i'm thinking i'm not running too big of a risk off the tires not grabbing with an almost stock 350.
so, the torker ii seems mis-matched to me. being wrong about that would make me happy.
 
#14 ·
Torker II wont be a good intake.Single plane open plenum chambers actually kill low end torque.
A stock intake or performer is good.
IIRC you need to run the 72-76 gaskets on the 71 and earlier heads to seal the intake at the exhaust crossover.
Wallace racing has a guide for that in the text articles. I was looking there a whil back for the same info. I have 1972 heads that I was thinking of running a 1965 intake on.
Cam should be OK.You could go a tad bigger, but the cam you listed should give good response on the street for a close to stock motor. The lift is better than stock so it should help on the low end .
 
#15 ·
Use the 350 block
Use the #94 heads
Use the 10/10 crank
Use the bearings you have too
Use the 76 intake you have , just need the 72-79 intake set for it to work. Use a 1972 up gasket set for the assembly.
You also have timing set , use that
The cam you listed 198/212 @.050 is an ok choice for a close to stock setup
About the only thing I dont see is an oil pump and gasket set. That shouldnt run more than about 200 bucks . That will give you a running engine.USE A STOCK Pressure Oil pump, not high volume/high pressure.
Do you have timing cover and balancer/pulleys and engine brackets?
Is the intake a 2 barrel?
 
#16 ·
i already bought a gasket kit when i got the car and the 350 did come with an oil pump. i've got a couple of timing covers (2 455's to rob of parts).
i'm transferring as much as possible from the 70 455 to the 350. i still have hopes of building the 76 455 if the block checks out.
now, in alabama we pretty much don't get cold weather. i think i want to completely block the exhaust crossovers.
will the stainless steel plates do the job? will i suffer exhaust leaks since my heads have the 4 bolt hole pattern? will shimming the center of the head make it more of a possibility? because it seems like that's basically what i'd be doing
does the "shoving tinfoil down the port" trick work or is it a recipe for disaster? i'm mostly interested in this because it supposedly improves the exhaust note. i'm not expecting a lot of gains from it.
will the 670 cfm carb be too much for this engine?
 
#17 ·
i've got to get more sleep. the crossover and the manifolds are two different problems all together. i'm not thinking straight.
i just checked and the '76 intake and the '71 heads actually have the same ports i'm guessing my '71 350 is actually a '72 350 that was cast in '71.
 
#18 ·
I wouldnt be shovin tin foil in there. You can completely remove the crossover part of the manifold, almost surgically if you will, and make some 1/4 inch or 3/8 plates to cover the ports in that area. If i have a pic of one done that way I will post it so you can see. It will make better sense that way.
 
#20 ·
This is a photo of a "divorced " crossover from a ram air 3 I think.
The reason I posted it is so that you can see what needs to be cut off your intake.
On your intake, the crossover is actually part of the casting of the whole intake.The view of the one in the picture is the "shared" section of your intake.Take a goos look at it, you will see how it is made. Just cut that part off of your intake, and make a pair of plates as thick as your intake bolt flanges, and stick them over the heat riser ports in the heads, then bolt it all down.
I saw one on E bay a while back a guy had cut, he did a nice job, had plates with it too. The picture would have been a great example to show you, but it has been sold, and I didnt save a pic of it. (wish I had)
 

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#22 ·
well, since the ports match even though they shouldn't i'm not going to worry about blocking them for now.
i saw one that someone had cut on another forum. it looked good.
my plan is still to eventually build a big cube engine, so i'm trying to make myself lighten up on this build a little.
 
#24 ·
Cool. :thumbup:
Tomorrow I am going to pickup a 400 481988 casting on the block.
Its complete carb to pan. water pump to tailshaft on the trans.( It comes with a t 400 )
I will be stashing the T 400 for now. The block is going off to the mnachine shop for hot tank, magnaflux and sonic testing. Then its going in a bag after it gets oiled down.
Never hurts to have a spare. Eventually I will build a 462 out of it.I still have my 389/400 build this winter.
I needed th quadrajet intake and carb. Plus it has A/C hanging off of it and a starter too. Lots of goodies there.
 
#26 ·
My cousin has a 69 firebird also. I am hookin him up with the AC pump and brackets. My 64 is a non AC car. Doesnt get real hot here in Pa. so dont need AC. It would be nice to have , but I am not gonna go all out and put AC on it. His bird had AC from the factory, and the pump and brackets are MIA.
 
#27 ·
yeah, it's only going to get up to 80 down here tomorrow. there's a cold front coming in next week and we'll have highs in the 70's. we get maybe 4 or 5 weeks of cold weather most years. we get about 9 months of summer, though. mine still has most everything but the compressor. i'm not going to put a/c in until i drop a bigger motor in.
 
#30 ·
latech, thanks for keeping me in mind. I used Fel Pro 1233 gaskets for my head\intake manifold combo and it worked great. Now to get the starter back on and I will be in business again. Check my photo gallery to see a few pics of my intake manifold. It has two different size cross over ports. bt
 
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#29 ·
i should have the 350 up in a few weeks. unless i luck into a good 455 block i'm more likely going to use the 64 heads on a 400 and call it a day. if the 350 doesn't absolutely make me want to throw rocks at this car it may be years before i even bother with that. i'm not planning on going to the track or racing tennagers at redlights. i may find the 350 is all i really need. honestly, i traded the torino for it less than a month after i got it running. if i get this car going and somebody comes along with a finished mopar, or the right chevelle or whatever i decide i'm in the mood for this thing may end up gone that fast too. this is the result of a bunch of trades that started with a '67 c-10. the money has slowly added up but this car has upgraded suspension, you could eat off of almost any surface on the car and the interior is in 85% plus condition. the next step will be something barrett jackson finish quality but non-matching numbers.
anyway, deer season opened here today so i'll be focused on that for the next month or two. and i need to start throwing money at barns and fences after that.
chances are that i'll drive the car with the 350 and be happy for a few years.
no information is useless.
thanks
 
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