[prostreet64]

Having trouble finding 1&7/8 or 2" d-port headers for second gen Firebird/TransAm. Any leads or are custom headers the only option?

[Skip Fix]

I think Herb Adams used to use Hooker Super Comps on the old Fire Ams. Number 4109. Looks like Jegs ships them from Hooker 3/3 shipping if ordered.

[tom s]

I think Hedman at one time had 2in for pontiac.They used a adapter plate that went to the heads and the header bolted to them.Im sure they still sell the plates and the gaskets for the plates.Tom

[Lee]

I got these from Steve C. a few years ago, then decided to go much milder with my car. Dents and such to install them on his '70 T/A. Steve had a high-end coating applied - it has stains but is still pretty solid.

It has the 2-piece flanges, where a flange bolts to the head, then the header bolts to that flange.

I'd love to see them go to a good home, make me an offer.

[25stevem]

You don’t need a 2” header unless your exh ports where gasket matched to such.

[tom s]

You really need the plates even with 1 7/8 on D ports.Tom

[tom s]

Once you use the plate system with Dports you will never want anything else.All the header bolts become EZ to put in!Tom

[prostreet64]

Tom, I was about to ask about the plates but your last post answered my question, I think. Was there any other reason to have them except to make the header bolts easier to install?

[tom s]

You really could not use large tubes with Dports was the reason.Tom

[Skip Fix]

I remember those headers on Steve's car!

"You don’t need a 2” header unless your exh ports where gasket matched to such. " Maybe even if not. Friend's E head 45 640 HP with 2 headers. Exhaust ports much smaller than 2" closer to 1 3/4 to 1 7/8. Did a pull with my 1 3/4(about a 6-8" section)-1 7/8 Hedman step headers killed 40 hp!

[prostreet64]

Skip, I am not sure I am following your last post. Are you saying the 1&7/8 Hedman step headers lost 40 hp over your 1&3/4 headers?

[67Fbird]

would be reasonable unless you are turning the RPM to utilize that much flow. Regardless of rpm you will lose TORQUE for sure.

[Skip Fix]

No they are 1 3/4-1 7/8- E head exhaust ports are basically 1 3/4-1 7/8. They lost to the 2" that were bigger than the E head ports. So a port match was not an issue the 2" were bigger and picked up over port sized. Lost TQ too so that blew the smaller more TQ myth on that motor.

[Steve C.]

Here is a link to the headers Lee pictured in post #4

STREET and STRIP Hedders; 70-81 FIREBIRD 400-455; 1-7/8 in. Tubes

https://www.hedman.com/product-detail/35145

I used them on a 4.210 stroke 462 with 280 cfm d-port heads.
The engine made 626 hp at 6400 rpm ( on a generous dyno ! )

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[prostreet64]

Steve, were those dyno #s through a full exhaust system? And if so was it 3" with some type of straight thru mufflers like the Dynomax Ultraflows or the Pypes Race Pro? My new engine is running the KRE 325 d-ports with the Northwind intake and a QF 950 carb. Also a 262/270 solid roller. I will have a full exhaust system. Just want to make sure the headers and the exhaust system are not a limiting factor, as much as that is possible

[Steve C.]

prostreet64

That HP number was from a engine dyno, not a chassis dyno.
It was built in 1998.

Those Headman 1-7/8" headers mentioned above.
17229 - Dynomax Ultra Flo Welded Muffles.
Full 3-inch exhaust system including the tailpipes.
Dr. Gas X-pipe

Victor intake / Brad Urban Stage III 750 Holly carb that he rated 926 cfm.
UltraDyne 300/307R8 solid roller
264 / 271 @ .050
108 LSA
0.689" gross lift
12.49 compression

10.68 at 125 mph


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[prostreet64]

Steve, thanks for the details; it gives me a pretty good idea of where I need to be headed as far as the headers and exhaust system is concerned. Also, would you say the Hedman headers fit with similar clearance, in particular ground clearance, when compared to other makes like Hooker or Doug's?

[Steve C.]

I have no idea of how they compared to other brands.

Set up at the time:

6 point roll bar, sub frame connectors.
Landrum 300 lb./in leaf springs with Cal Tracs traction bars; Competition Engineering drag shocks, front and rear; all sway bars removed; Moog six cylinder front coil springs.
Front tires were 26-7.50-15 M/T Sportsman. Rear tires were either McCreary L-60-15 D.O.T or 28-10.5-15w M/T slicks.
Brakes were OEM, front disc and rear drum.
Race weight about 3790 lbs.

It sat a bit low in the front. On occasions it would scrape the collector flanges.


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[prostreet64]

Okay, thanks. It sounds like you had a great combo! Hope I can get in the same ballpark.