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Big Block Pontiac Performace

7.7K views 25 replies 14 participants last post by  tempt  
#1 ·
Iam bilding a 37 pontiac and i wont a big block with a blower. But i dont know anything about pontiac. so some sugestions on what engine i sould find and what i should do to it. thanks for any help
 
#2 ·
All Pontiacs from the 326 up to the 455 use, essentially, the same block. They are all "big blocks". I would look for a 455. Cubic inches are king and this will do it for you.
Here is an article Car Craft did on a junkyard 455. http://www.carcraft.com/techarticles/116_0306_pont/
Look it over and ring back with any questions. Lots of Pontiac guys here...
:thumbup:
Mark
 
#3 ·
As far as building a Pontiac for a blower motor go with a 455 with large chamber heads such as 4Xor 6X to keep compression down. Use good rod bolts as stock Pontiacs have a tendency to stretch, I recommend ARP for rod bolts. Also if you feel the need for better rods either 421SD or 455SD rods are the best that Pontiac made but stock cast rods will work. Use forged pistons and good rings and use a half groove main bearing as Pontiacs have tendency to have alot of force on the downstroke and will form a ridge on the crank over a period of time. Use stainless steel valves and have a reputable shop port and polish the heads and use good springs and roller rockers. As far as cams I'm not sure what to recommend on that one but check with some of better known builders that specialize in Pontiacs for what type of cam to use as far as cylinder pressure is concerned along with how much boost you may want to use along with whether to overdrive or underdrive your set up.
 
#5 ·
thanks astro for that cool link on a 455 hop up which would be about the same as a 400. i didnt see anything at the blower site for pontiacs. it would be expensive as hell tho. the main problem with pontiacs is the heads totally suck for the most part. a 326 is about the same as the 455 except the e heads dont fit. a friend put an edel intake and thorley headers on his 326 and didnt notice much of anything. like about. but we cant go out and get heads. there are some good poncho heads out there so you have to be carefull when you buy the engine or plan on buying them later. i've also seen a post where someone makes a crank to stroke the 400 to 462 and am trying to find the mfg.
 
#6 ·
Here's a link to a place that sells pontiac stroker kits . This one doesn't seem to steep. But they have an assembly to go from 487 - 501 CI.

And as for supercharging a pontiac, it doesn't seem to bad. I found a manifold for somewhere that was $500, not much more then a chevy. From there, the cost would be the same for anyother blower.

I'd like to see how a stock pontiac head with some light port work would handle boost. I think you coulld make big torque with a roots blower. I haven't done to much research yet as I am getting my T/A in a few days.

Sorry for bringin such an old post back up. :nono:
 
#7 ·
From your question, you don't really say you want to run Pontiac power. While Pontiac engines are just fine, they do cost a bit more to build compared to the Chevy Big Blocks.

I also guess from you wanting a blown big block your going to be spending some big dollars either way. Its really your choice, there are more after market parts for the Chevy's, so they are a bit cheaper to build.

Build what you want, but please keep it GM!:thumbup:


bonuts
 
#9 ·
Big Block Pontiac

If you want to run a 455 Pontiac engine look for the YH engine if you can find one. Casting # is 9799140. You will find the YH code on the front of the block below the pass. cylinder head. The YH is a factory 370 HP engine. You will find it in a few 70 Pontiacs like the Bonneville or Catalinas. I built one back pretty much stock just some stronger rods and the only thing that was changed above stock was using the Lunati Pontiac Ram Air IV cam. That was paired with a Edelbrock intake and a HEI ignition conversion. The Ram Air IV cam picks up the bottom end and has a nice "chop" to it without bouncing all over the place and has no problem going into gear without a stall convertor. The rebuild with machine work was around $2,500. That's not a bad price for complete machine work and having everything replaced and upgraded. Linked to a Turbo 400 Transmission it will push you thru the drivers seat on acceleration. But it's a dependable, streetable engine. So without spending a fortune to make horsepower you can have it the way it used to be straight from the factory.:thumbup:
 
#12 ·
400 or 455?

If you can find a 455 that's great although they are kinda scarce.

e.g. took a whimpy 326:
I put Lunati cam, edelbrock performer RPM, and 2.25' duals on hedman headers and I can bend my '66 tempest out of a straight line when I hit it at 60.

Not so whimpy 400:
I am now building a '67 400 (yes, out of a catalina) with #143 10.5:1 heads (if you can find these heads, grab them, they have bigger chambers and valves). 75cc chambers. 1.92 intake valves! that you could punch out the edelbrock spec of 2.11 if you want to. (probably will)

point: (and I have one,) that you can do a lot with the heads to increase power. 4x and 6x are nice, but the ultra rare stock heads could be---- almost as good as the alum eddy's for a lot less. Do your porting/polishing get 1.65 roller rockers, oversize the valves and I promise you can build a 400 hundred that will require regular dental work!

tempt
 
#16 ·
400 vs 455

Hey Guys

I'm new to this, I hope someone can get me going in the right direction.. I have 2 engines one of them is a 400 G018 with Casting #15 heads G038. The block codes is YE which makes this engines a 340hp 10.5 to 1 compression. The other one is a 455
J192 and the block codes is YC. The heads are 4X K172. Which makes this a 250 hp with 8 to 1 compression.. In saying all of this.. These two motor are the first I have tore down to the block. Now I don't know which one to go with to rebuild. I'm restoreing a 1966 4-door bonneville which was been in the family for 38 years. I just want when this car to crank-ups peoples heads to turn and pull out on the road push the gas and the tires to light up... Hopefully someone can get me in the right direction.. I would like around 400 to 600 hp on pump gas... Is this possable... The car will be going to olded curiz and some show not on the Drag Strip...

Thanks SpeedCrazy
 
#17 ·
Bullheimer,

The link below is good to confirm valve and chamber sizes for the 326-455 pontiac. I think your question might be----
Can you put a 4bbl on heads intended originally for a 2bbl and the answer is yes, in some cases, I won't say most-- the spec sizes are the comparable anyway.

http://www.angelfire.com/on/geebjen/heads.html

but yes, mine originally had a 2bbl on it. Granny motor, came out of a 65 tempest with 55k, old lady turned it into a cigarette case on a telephone pole and I bought the 326 for $150.

I have ported and polished the heads since, but I need more cubes, that's why I'm building the 400. I'm already scouting for a 455. For what it's worth----
some things you can do to make your heads "bigger"
-taller rocker studs (cheap)
-roller rockers(279)
-port/ polish(free)
-over-size valves/job (about 200 at shop)
-I have heard of guys even powder coating
to increase flow(haven't confirmed this works)
-intake /carb spacers (about 40)
you get some major fuel velocity and low end torgue from this simple/cheap trick
 
#18 ·
Thanks for the infor, I went to the web site you gave me... Ok the heads I have for the 400 engine are 75cc which came with it and the heads I have for the 455 are 114cc.. If I put the heads off the 400 on the 455 will it make to much compression for pump gas or would you even do that... The 400 engine is a 1968 and the 455 engines is a 1973...
 
#19 · (Edited)
Bull

http://www.taperformance.com/faq's.htm

Another link, I know. This explains beyond my scope, what you would need to do if you wanted to top your smog 455 off with the retro 400 heads. It's a forum that makes alot of sense once I read it. and yes, I would have had the knee jerk "no, don't do it" but this is good info. By the way, one of the concerns the forum doesn't mention about head swapping is the fact that this is not an exact science. in a word, not all 455 blocks will play with all 400 heads and vice versa. So I would do some homework and even do a dry run with the swap to make sure they play well together on the stand and even put in the valve train to check clearances. Big things to watch:
--do the lifter seats "match" the bottom of push rod.
--are you going to run roller rockers if so, do/will they match up with the hybrid push rods you will end up using
--will the gaskets lay true
--check head bolt depth on both sets to see if they match.
--make sure you have figured out how these suckers are going to get oil--either through a galley by the lifter chamber or the hollow rod (not all rods are hollow)
 
#21 ·
tempt, since this thread was brought back from the dead, what are the specs on your Lunati Cam? i just bought a summit 2800, which was there top of the chart cam, pretty lame, but i havent installed it yet as i was gonna just put it in with my stock 2bblheads. but if i can find 4bbl 326 heads i would be able to bump the cam up. what do you think of the 2800?
 
#22 · (Edited)
Bull,

Here is a general description:

I will access lift, duration, separation for you if you want or you can take part number and go to Lunati.com and they will spell it out for you.
Sorry, Haven't looked at the specs since april, A Lotta 400 cid water has gone under the bridge since then, don't remember 326 bump stick specs: here's the part number though and how I would describe it's use for you
o00072LK would be the cam and lifter part number for your car. This cam has a
lopey idle, will work with your transmission (assuming you still have the slim jim 2sp or th350,
(will handle converter and minor engine mods.
Price is $149 it's a great cam, great low-end torque and w/ the right richness on the secondaries, it will howl at WAT too.
... just looked at the 2800; this appears to be a stock cam replacement which is fine if you don't intend to make any mods. The whole thing here is that a bigger bump stick won't do much good without any air. Those heads gotta go eventhough you mentioned 114cc chambers, that's decent man--- I would do some research and find out the what intake/exhaust valves are and maybe upsize a little at the shop and go with those heads, put that 455, '73 you probably know was the last of the heavy hitter-455's to come out of detroit. As far as the 326 goes, I would pump it up with a better intake and cam, port the heads, then at least you could sell to an up-an-comer when you step up to the 455??
 
#23 · (Edited)
yeah the heads always seem to be the weak link with a pontiac. but i had a big time poncho builder say the 2bbl heads i had would be incredible when hogged out. must be because of the chamber size you mentioned. i dont even remember who it was it was so long ago. what caught my eye was you said your 326 would twist the car up pretty good. i dont have the means to get a 455, and i am using this car for daily driving, i really like the milage i am getting, i do have the stock 2 speed, but was wanting to upgrade to a 4sp auto. got any recommendations? i take it your 326 had 4bbl heads? i want it to sound like a hot rod, not a grocery getter like now, and be able to burn rubber when its not raining:cool:
here's the spec on the summit 2801:Vendor Summit
Product Line Summit Camshafts
Cam Style Hydraulic flat tappet
Basic Operating RPM Range 2,000-4,500 RPM
Intake Duration 050 inch Lift 214
Exhaust Duration 050 inch Lift 224
Advertised Intake Duration 272
Advertised Exhaust Duration 282
Intake Valve Lift with Factory Rocker Arm Ratio 0.442
Exhaust Valve Lift with Factory Rocker Arm Ratio 0.465
Lobe Separation (degrees) 112 . think it would run with my stock heads? it's alittle bit milder than the one you ran from Lunati, that was Lunati's top of the chart cam btw.
 
#24 ·
Burn rubber when not raining, that's hilarious. I'm sorry, I thought I heard say you had your hands on a 455 at one time. The th700 is a great tranny w/ overdrive. You can buy one 4-about 3200 or take th400 and add your overdrive kit (4th gear) for about 2100 and it will be switch operated. Very cool option---- you essentially end up with twice as much plant at the track. Manual shift out of the hole wrap it to 4000, then hit overdrive and take to half gear in between each gear. BIG ADVANTAGE.

I have aluminized 2.5 pipes (unless you're running 500hp+ this is more than you'll ever need, don't ruin your bottom end by listening to these guys who bad-talk "back pressure"-- you need the right amount of back pressure in order to have any bottom end) and I kept the J pipes at 2.25 (better low-end torgue with a throatier sound (best of both worlds) my own recipe. Mufflers are dynomax --superturbos and my wife complains that one of these days our fish is going to commit suicide and jump out of the tank when I start her up. Shakes the sheeoot of the house (attached garage).
Bull, trust me, you can make a 326 perform just like a small block if you want. It shouldn't cost a lot of money either. The heads are the big thing.
Intake: Get an edelbrock performer RPM (the 'rpm' is the highrise performer)-- yes, it will still fit under your stock hood, but I put an aftermarket scoop on (Lund.com), with 2" spacer, more fuel velocity; that has the hood looking exactly like a goat hood for about $69--. This arrangement creates a ram-air effect. If you look down the scoop, all you see is cleaner--wham!! AIRHAMMER!! I did my own paint work. I will try to start one of these project folders sometime and include pics.
 
#25 · (Edited)
my wrecker here will get me either the 200-r4 or a th700 for $250. i am trying to decide which is better, has the best gear ratios although i've heard 700's would need an adapter plate. i have no idea what my gears are but they're spiders. i had a chance to get a low cr 455 but he wanted like $450 so i passed. i would have had to get heads too. (i bought a performer already so the rpm cant happen). i also dont have headers either because my friend put thorleys/performer on his catalina and it didnt improve it much. wonder what you think of maybe trading in the 2800 for the 2801 with stock exhaust, performer, Q-jet i just scored off a '76 Olds 350, or if i should just put in the 2800. i really doubt i'll be able to change trannies before summer unless my uncle dies, and i've seen some unreal 1/4 mile times from cars with only one tire spinning. i will not be doing any headwork to my heads either other than gasket matching them, what about using the 2800 with higher ratio rocker arms?

DAMN, TEMPEST! I just noticed you only have like 6 posts and there just about all in this thread!! not much of a talker are you? that's pretty weird since you probably know alot, at least about pontiacs. loosen up bro! it's good to hear from you! i re-read your posts and it seems like you did in fact put that Lunati in the 2bbl 326 since it had a 2bbl on it stock. thats the good news. bad news is i still have this 2800 cam
also, the taperformance link doesnt work anymore
 
#26 ·
Sorry Bull,

Just changed jobs and it's kept me hoppin'. Sounds like a you gotta line on a 455. That's great, for 450 i'd snag that. They aren't on every street corner anymore---

and no, I don't know a whole lot. I just hang out with old guys who do--- and do and repeat as they tell me ))

I check out the lift on the 2801 especially if you are thinking about the scalability of your plant long term. Gently reminder---
You said it yourself, the performer, and headers won't do any good until the air is right.
#1 1.65.1 (7's might even go) srew-in studs
#2 cost 28 bucks a head to mill--- big air-- big fuel!!
#3 bigger valves- if your going to replace the valves anyway, you can get a major response from this, I'm doing it now w/ the 400 intake--1.96 to 2.11's ex-- 1.64 to 1.77's
then-- your 2801 will play big #'s with perf and headers because you'll have some wind.
-----Way Off the subject-- I just installed a gas powered 100,000 Btu airplane hanger heater in my garage Whoo Haa!! it was 11F last night and 69.4f in my garage. I took off valve springs in my socks!! this thing's a monsta!!