[hcompton]

Originally Posted by cobalt327

Better than nothing I suppose, but not a 4-tube.

They gave more hp and tq than any of the four tubes with in a hundred bucks. Even the guy at jegs confirmed that unless you going with full length 600 headers these are with in one or 2 hp higher or lower of just about all the cheap headers on the market. They really out performed a lot of the cheap hooker and other four tube headers. But once you got into good flowing stainless headers they were out shined. With a sbc small runner work well but the big poncho like the flow. 1 5/8 inch primaries and 2 inch for the double is plenty big enough. The center cylinders dont fire right on top of each other so no real need for a bigger tube. I think its more for fit then anything else.

Since the two center ports are so close to each other headers dont actually fit well unless they have the pipes flatted to fit the ports. And with cheap 4 tubes they just weld em on and ship it when you look from the valve out you can see the pipe does not properly cover the ports if the pipes are circular.

[77pontolds]

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!!!

[cobalt327]

Originally Posted by hcompton

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

[cobalt327]

Originally Posted by 77pontolds

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.

[hcompton]

Originally Posted by cobalt327

Don't believe me? Fine. What if Jim Hand said the same thing?

Building a Strong Street Machine - Part 12

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.

Fyi hooker 1 3/4 long tubes are not the same price as the 3 tubes about 100 bucks cheaper and only a few hp down.

Just depends if the cost and clearence are worth it for the four tubes.

[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.

77pontolds,

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.

Jim

[cobalt327]

Originally Posted by hcompton

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.

[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

[hcompton]

Originally Posted by 77pontolds

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!!!

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.

[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.

FWIW

Jim

[77pontolds]

Originally Posted by hcompton

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!!!

[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!)

Jim

[77pontolds]

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.