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77gp
Tribal Scout

14 Posts

Posted - 05 Mar 2015 :  7:36:56 PM  Show Profile  Reply with Quote
Hello all, I am building a set of headers for my 77 Grand Prix and I was looking at images on google and I saw a set with the two center ports combined into a single tube. Has anyone used a set like this? Does it stay 3 tubes the entire length? Obviously this tube needs to be larger diameter does anyone know the tube size of this design? Is this a poor design from a performance standpoint?

Blued and Painted
Chief PONTIAC

USA
3404 Posts

Posted - 06 Mar 2015 :  01:52:01 AM  Show Profile  Reply with Quote
You defeat the purpose of headers when you connect the 2 cylinders on each bank.

http://www.hotrod.com/how-to/engine/hppp-0312-headers-vs-manifolds/


Bull Nose Formula/ 461/ Q-Jet/
TH400/ 3.08 8.5 / R44TS.

Edited by - Blued and Painted on 06 Mar 2015 01:53:01 AM
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77gp
Tribal Scout

14 Posts

Posted - 06 Mar 2015 :  07:24:14 AM  Show Profile  Reply with Quote
Kinda what I thought, thanks for the quick reply
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Phil
The Great White Buffalo

USA
7214 Posts

Posted - 06 Mar 2015 :  08:52:32 AM  Show Profile  Reply with Quote
Yes, that was a cheap header version like the old "Blackjack" $99 headers back in the 80's. Surprisingly they didn't fit well either despite the extra space provided by the missing tube.

I had a set at one time on a daily driver and replaced them with another cheap set of headers (Cassler) except the new set was 4 tube and fit perfectly. Performance was better with the 4 tubes while I didn't notice any difference between stock logs and the 3 tube headers.

Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.
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Blued and Painted
Chief PONTIAC

USA
3404 Posts

Posted - 06 Mar 2015 :  8:21:01 PM  Show Profile  Reply with Quote
Could be a moot point being 4 cylinders are connected through the exhaust crossover. Preformance camshafts work with the scavenging effect of headers.

If building headers, tri-y's could be and option.


Bull Nose Formula/ 461/ Q-Jet/
TH400/ 3.08 8.5 / R44TS.
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77gp
Tribal Scout

14 Posts

Posted - 11 Mar 2015 :  9:40:15 PM  Show Profile  Reply with Quote
Well, I cut out 2 sets of flanges so I will do 4 tubes first but if I don't like them I can do 3 as a last resort
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