Exhaust manifolds/dougs headers test over
 

sometimes its fun to test, and its nice to be able to reverse to what was better no harm no foul. all part of hobbyin'. and now being retired its even more fun because I have time for it.

same engine in the pics below. propelled me to 11.80s at 115mph all day. was so consistant I actually ran 11.86-11.87-11.88 all together. the pontiac blue pic is whats in my car right now. same exact engine. only diff is rpm intake manifold and oversized round port exhaust manifolds. both are 1,000cfm carbs. shaker455 supertuned the qf on the black engine and it was perfect. tall valve covers required, I have stud girdles on there. scorpion 1.65 roller rockers, no issues iv'e seen folks post against those.

so i'm going to return to dougs headers, this engine does not like the manifolds. mercy you can feel the difference in power to. i'm a more power the better so no, I don't know what I was thinking. the engine is actually idling very nice right now but not like it did with headers. its running great but going to return it to what it should be.

question: are dougs 1 7/8 round port headers still the best fitting on 70-81 Firebirds? if not, whats the pontiac go to brand now.

going full tilt, headers and electric cut outs. already have 2 1/2" h pipe exhaust with dynomax ultra flows. looking forward to the mod on a snowed in winter day(s).

I may try an edlbrock torker2 or other single plane manifold as well after the exhaust change. thoughts on going back to a single plane welcome. fun stuff!

Please keep us tuned in to the results.

I'd be more interested in how much of a difference. Since you already have drag strip runs with headers, why not run the car with the manifolds since you went through the trouble to put them on, and put up some comparable timeslips.


As far as electric cutouts, worthwhile in my opinion. We have them on several cars and a few have been on chassis dynos, with them closed and then opened they have always been worth a few ponies, but are the most fun to play with on the street.

it wouldnt be a good comparison. engine was in a 69 gto, 4.30 gear, 28" street slick radials, 1/2" fuel line, then the headers & victor intake, wilson spacer also.

no 1/2" fuel line or electric pump now, although I believe the 3.73 gear now is far better for the combo. i think woulda been faster before with the 3.73. same torque converter though as before. i'm just wanting to sweetin this particular combo to a perfect clean tune. if the rpm manifold does well i'll leave it.

........electric exhaust cut outs just for street fun.

is the stock oil filter housing and filter retained with firebird headers?

When I had Hooker headers on my 70 bird the stock filter and housing worked fine.

I have had good luck with Hooker 2". One I use for dynoing the tube near the oil filter needed a big massage to get the filter off. None of my other sets have.

Somewhere along the way I believe Hooker made a change to the 4202 Firebird headers. The early units need the filter housing from the first Gen Firebird or full size cars. That seems to be corrected and the later version works with the correct filter housing.

Pauli I have 4 sets. I think all were after they swapped to Mexico. A few slight variations in the sets the dyno set was the only one that tube was just bent a little different. Some collector length a little vairs-1/2-1" and one the flanges are upside down from all the others.. All of mine I think are late 80s to current and do take the late filter if they are bent right.

They do need a little massaging on #1 for an IA block freeze plug boss.