irocinblue89

iTrader: (2)

Like the title says I have the gmpp fast burn heads and doug's long tube headers and I have leaks on the bottom. The mechanic thinks there is not enough material on the bottom of the exhaust ports for the headers to seal. I am not very educated on the different heads. He thinks the headers are for 86 and down sbc, and the fast burns are vortech type. Did anyone else have this problem and if so how did you fix it? thanks

DAVECS1

iTrader: (2)

I have had slight fitment problems with some headers and vortec heads. First make sure the header is not contacting anything else when bolted down. If it is you need to clearance what ever it is contacting. Next use the the correct felpro gasket for your ports. The blue exhaust manifolds gaskets will seal almost anything as long as you select the right port configuration for your headers. The come in round and square port, as well as different diameters.

TA

iTrader: (1)

I have Dougs' headers on Vortec-pattern heads, and they did leak. I bought 2 sets of gaskets and double-gasketed them and did several tightenings after some heat cycles, and they no longer leak, but there are spark plug clearance problems that required denting the headers.

Also, make sure your headers are not hitting your passenger side lower control arm bracket or the transmission converter cover flange, as this will not allow the headers to sit against the heads properly.

Good luck
TA

Air_Adam

Correct me if I am wrong - but those GMPP Fastburn heads use an LT1 style D-port at the exhaust, instead of the traditional round or square ports, no?

D-port heads do not seal well with traditional SBC header flanges with tubes under 1-3/4" diameter. But - there are D-port headers available for a 3rdgen F-body. If I remember correctly, Hedman makes them. You can see the exhaust port shape difference in these two pics:

D-Port Heads



Traditional SBC Heads

DAVECS1

iTrader: (2)

You are probably right. It has been about 5 years since I have even touched a set of those heads. Just trying to help out with some of my dusty memories.

sailtexas186548

iTrader: (2)

my round tube hedman lt's seal on my d-port aluminum heads (L98 vette heads) wihtout a problem after several tightings and heat cycles, i used MR. gasket copper

Air_Adam

I'll bet that even though those L98 heads are D-ports, they are substantially smaller ports than the Fastburn heads have... the intake ports are about 170cc on your L98s, VS 210cc for the Fastburns. The exhaust ports will be larger to match, and may not seal to headers like yours, even when your L98s do.

irocinblue89

iTrader: (2)

Like anyone who does swaps like these I am tryin to iron out all these kinks. Thanks for all the info. I cant take the doug's back as I have started the motor with them on. I'm gonna run up to summit today and see if they can hook me up with a good set of gaskets and I will heat cycle it and just keep turnin the wrench. I like the doug's headers, and would be upset if I had to to change them.

TA

iTrader: (1)

I'm actually running ported E-tech 200s, which are manufactured at the same foundry that makes the Fast Burns, so I think our exhaust ports are very similar. I needed to do a small bit of cleanup on the header flanges to gasket match the headers to the D-Ports, but there is plenty of sealing area there, they just need to be TIGHT!!

TA

irocinblue89

iTrader: (2)

TA did you use 2 gaskets from doug's or did you use two different one's. These things are still blowin out the bottom and they are not hitting anything. Heading to summit now, gonna get some fel-pro's.

TA

iTrader: (1)

I used 2 sets of Mr. Gasket for the D-ports and used them as a guide to clean up the headers. Make sure and gasket match them, as the headers are designed for the rectangular ports, and there is plenty of meat to do it right.

TA