I did a search on this and came up with nothing so....

I have a set of gm fast burn heads, and they require LT1/LT4 style exhaust flanges. so i was wondering if i got a set of LT1 headers for a 4th gen, would they fit in my thirdgens, or what modifications would i need to do?

 

nope, your best bet is to modify a set of third gen headers.

 

the only diff is the LT1 style is a D shaped port, so look for that on headers for your heads


regular third gen headers will work, most gaskets will seal ok, but optimal flow might not be realized

 

paceparts.com has a listing of heddman headers to fit dflange

 

thank you for giving me this information, i was searching some more about LT1 engine swaps and stuff, and alot of people seem to have used the SLP 1 3/4' shorties, would these work for me, and if so what is thier part number.

 

I have a set of FastBurns being readied for a 409 (.040 over 400) transplant. In addition, I have a set of 1-3/4" SLPs (no smog tubes) on my GTA which replaced a set of Edelbrocks.

Before mounting the SLPs, I bolted them (while on my workbench) to a valveless FastBurn head and then looked from the chamber side through the exhaust port.

There is a MAJOR mis-match between the 1-3/4" SLPs and the d-port exhaust of the FastBurn heads. The actual cross-sectional port opening of the SLPs are about 1-3/8" while the FastBurns are 1-5/8" at the same point. The round part of the "D" shape extends far enough up into the SLP flange that I don't think it would be safe to "port" the header that much.

I would not be surprised to see a possible loss of 20-30 hp due to such a problem. Perhaps you wouldn't even see any gain with the FastBurns over the original heads.

My advice (and what I will do) is to save up your money and get the "proper" headers. At that point, I'll sell my SLPs.

Just my 2¢ worth.

jms

 

thank you for that information jms, and what exactly do you mean by the "proper" headers, do you mean custom made, or is there another set out there?

 

Hedman headers, as mentioned above, is one option I am considering.

I would like to see a set in person, first, just for my curiosity.

I've also considered modifying a "normal" set of long-tube third-gen headers by cutting off the flanges and welding on a set of d-port flanges.

I, like you, have not seen a satisfying solution, yet.

jms

 

i have contacted most of the major companies, explaining my situation, hedman, hooker, slp, and i actually like the idea of taking third gens, and modifying them with d-flanges, the only problem with that is cost effectiveness. unless you just happened to have d-flanges lying around. let me know what you do.

 

I understand your cost issues. I am in somewhat the same boat. I am still "gathering" parts and think it will probably be another year or so before all the parts I've bought "meet" each other.


With all the LT1/LT4 type swaps planned or going on in the third-gen world, it does look like the header companies would pay a little closer attention to the d-port needs.

jms

 

ya, hopefully they meet that need, but ill do whatever i need to, if i need to go cut apart some LT1 headers, ill do it, but i just hope they make it easier.

 

i got a reply from hooker,and they said that the 2210hkr headers will fit our vehicles with the fastburn heads

 

I have been running Fastburn heads on my 406 for a year and a half now. I am using Hooker 2210 longtubes and they are working fine for me.

 

Hello guys, We carry 2 diffrent Hedman D-port headers for third gens. I have a pair in the shop right now un-coated. I'll see if I can get Dave to get up a pic on here tomorrow of the ports
JIMI @ ACS

 

Any pictures yet?
jms

 

alright Dave give up the pics manG