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Topic Review (Newest First)
05-19-2013 09:00 PM
400 pontiac

The engine responds better now, thanks to the demon. It has a pertronics hei dist, but is otherwise stock 71 in a 77. My parts car is a 80 turbo TA, and I'm interested in finding a new home for it. It has a 400 in it now , which I plan to keep for a spare for my car.
05-19-2013 09:23 AM
Mr. P-Body I doubt the intake helped anything but weight, as the factory intakes are excellent (yes, even the EGR units). But I'm glad you're happy! THAT is what it's all about!

Keep on Yakkin! (that's Ponti-YAKKIN!)

05-18-2013 10:06 PM
Originally Posted by hcompton View Post
Glad to hear it. Do you have alum intake and hei? Your set to enjoy. They dont need much to be fun.

The 400 will not show a stock 403 trans much respect. If you havenet already best to have a great trans built next. That should be the next biggest drop in et for single improvment.

Not sure what purpose the 403 was built for but it was not performance or tq. it was not all that strong compared to the beating a new 400 will take. So not even sure why they built then. The 350 from olds and chevy and pontiac was comparable and had advantages. I just dont see the advantage to the 403. Most of gm products have a perfect nitch where they belong and were properly designed to work great at doing.
Hello again, I have a edelbrock performer intake, and now a Demon 725. It runs real good!!!
01-21-2013 08:48 AM
Mr. P-Body Can't say 100% sure, but what I recall, the 403 was already approved by CARB (California Air resource Board) and the Pontiac was not. It was less expensive for GM to use the line data in other assembly plants, than to recertify the Pontiac for California. At the time, they weren't too concerned with selling actual performance cars as they were selling the "image" of performance. That's was the great era of "sheeps in wolf skin". You remember. All the "scoops" weere closed up, cataytic converters were choking things, vacuum lines everywhere... Hey, Chevy even got into the act with a "NACA" or "Douglas" scoop that was nothing more than a sticker on the hood of the revived (due to T/A sales) Z/28.

In '79. my brother and I went to various dealerships and test-drove all the "performance" offerings. The ONLY car we found rfom GM that would truly turn the tires over from a "standing start" were the T/As. But we had to go to Arizona to find them! A stock 403 car came with TH350, no other option. It wouldn't turn them. A '79 Corvette in Cal, also had TH350 as the only trans. It too wouldn't turn the tires over. -We DID find a 400/4-speed T/A at Mecham Pontiac (yes, the infamous governor, actually pretty nice guy and honorable business man) in Glendale, AZ. IT would rip the tires! Nobody had a '79 Corvette with a manual trans available for a test drive.


01-19-2013 02:16 PM
LATECH 77pontolds.... Good going congratulations on the finish up of your engine.
Glad to hear that you got lots of torque from that baby.
Enjoy.... LA Tech
01-19-2013 10:08 AM
Originally Posted by hcompton View Post
Lol how old is that article. They dont even make those 3 tubes any more. My three tubes from headman were way better than any manifolds and a few of the four tubes i tried.
So you're telling me you did back-to-back tests, w/ONLY the headers being changed? And you lost power w/which 4-tube headers?

More to the point, I DID have occasion to test 3-tube Hedman aluminized "headers" against a set of Hedman 4-tube headers on a 400 Pontiac belonging to my friend and neighbor, Bill Anderson. '78 T/A, engine I built, had a cam from HO, #12 heads. It picked up 1.5 tenths- WITH ABSOLUTELY NO OTHER CHANGES, other than the runs were made one week apart. I'll be glad to give you his email addy should you doubt me.

When you learn why a 4-tube header works better than a shortie/block hugger/3-tube header, get back to me. Has to do w/the scavenging effect that a 4-tube has that's disrupted when using a 3-tube. The age of Hand's article is irrelevant- what's relevant that you choose to ignore is the big tube never "peaks", and if it DID, the rpm would be too high for the smaller pipes.
01-19-2013 08:34 AM
Mr. P-Body Regarding flow and low-speed power, headers aren't really in their "natural habitat". I have no doubt, the three tube cheepies made more "seat of the pants" power than the log manifolds. I also have no doubt, on a dyno, the Ram Air exhaust manifolds make more power above 3,500 RPM than the 3-tube jobs. There is no way they can make more peak power than a good 4-tube header unless something is terribly "amiss" elsewhere.

Headers are not installed specifically for "flow" increase. The sound wave plays an important role in making peak power. Isolation of exhaust pulses from each other, and the length of the primary tube, have the greatest impact on power production from headers. The BIG difference would show clearly at a track with "open" headers.


Glad you got the 'bird going! Olds guys always get defensive when I tell them this about the 400 Pontiac. But it's true. Not many better street-performance engines than 400 Pontiac. Wait 'til you pump it up a little... (:- Ignore the buzzing in your ear about Chevys. If it were a Camaro, I'd agree with a Chevy... T/A and GTO were the top of their respective classes for a lot of reasons.

01-18-2013 09:19 PM
Originally Posted by 77pontolds View Post
Wow! You folks were right. The 400 Pontiac makes my Firebird haul 555. It makes me want to put casters on the rear. It is quite a difference from the Olds 403. Now I have to be careful when I nail it, cause when it shifts into second gear, it wants to go sideways. Fun!!!
Good deal! Must be running good- the Olds 403 usually is no slouch up to at least 4500 or so (stock). Stay safe out there and enjoy.
01-18-2013 09:16 PM
Originally Posted by hcompton View Post
They gave more hp and tq than any of the four tubes with in a hundred bucks.
Don't believe me? Fine. What if Jim Hand said the same thing?

Building a Strong Street Machine - Part 12
01-18-2013 09:03 PM
Pontiac 400

Wow! You folks were right. The 400 Pontiac makes my Firebird haul 555. It makes me want to put casters on the rear. It is quite a difference from the Olds 403. Now I have to be careful when I nail it, cause when it shifts into second gear, it wants to go sideways. Fun!!!
01-10-2013 02:12 PM
cobalt327 Better than nothing I suppose, but not a 4-tube.
01-10-2013 07:39 AM
Mr. P-Body Forget the brand-X carbs. Use a nice Q-Jet from '74-'80 or a good Holley. 750 CFM MINIMUM if you want that Pontiac to get beyond 5,000 RPM.

The "torque monster" Cobalt327 describes is a common "old school" Pontiac build. I had one like it in '85, in a '73 T/A. 12.50s w/3.73 gears, stock converter...

Who ever it was in this discussion that told him to "just use a Chevy motor" needs a "wake up call". And it isn't a "new" thing, either. GTO did NOT earn a reputation for getting BEAT... (:- When properly built, the Pontiac is among the very BEST street/strip engines "out there". Making over 600 HP UNDER 6,000 RPM is one of the reasons...

01-07-2013 06:34 PM
Pontiac 400

I haven't had a chance to lean into it yet because of the snow, but I think it will be pretty impressive. It has 3.73 rear end gears, a 200-4R auto, and a 625 Carter AFB. I'm going to try out a 750 Demon to see if it makes any difference, since it would be a loaner to check out. More later, Next it goes to the body/paint shop for a freshen-up, and to get rid of the hail damage. Thanks, Uncle Rich
01-02-2013 05:27 AM
Originally Posted by 77pontolds View Post
We finally got the 400 in!!! The problem was the "B" brackets don't fit an "F" car. Once I located the right ones and installed them, it all came together. That Pontiac engine leaves more room in areas where I need it, like behind the distributor. It looks really at home in there. As soon as I get done, I'll try to post some pics. Thanks again for the help. Uncle Rich
I hope you enjoy the 400 half as much as I did my 455. I talk about that combo ('81 Camaro/455/6X heads) too much- but it was the tamest, easiest to drive anywhere, everyday, regular gas, 3.31 rear gear, 650 DP, all steel, full interior, 12 second vehicle you'd ever want to see.

I mean, how many cars w/those specs can stage in Drive, mat the gas from an idle and let the tranny shift out on its own (no governor work) and still run 12's on street tires? With a 10-bolt 3.08 run the same way (in Drive) it went 13 seconds flat in the quarter. Oh, and it had a 4777 Holley on a Performer intake (not the RPM, it hadn't come out yet). It was a ball.
01-01-2013 09:09 PM
cadillacdave1 If you have the $$ try the edelbrock performer cylinder heads rather than rebuilding the old pontiac heads. You will get more power and reliability. The stock pontiac heads dont flow that well by todays standard. You can get torque from the old heads but not much horsepower. You would be limited to probably 375 horsepower with the old heads. Remember there was not much aftermarket support for pontiac engines like there is with chevy which has cheaper alternatives. You can build a 400+ hp sbc for 1/2 the price of a pontiac with less hp. Remember new and cheap sbc heads outflow old pontiac heads by a lot. Good luck with the build
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