ramdaspadhye

iTrader: (3)

I posted this in the external gen3 forum, but thought this one would get more hits...

A friend of mine asked me about this the other day, and it got me wondering...

For those of us who are swapping an LS into an older car that isn't near as popular as, say an a-bdody swap, do you think you could use a set of BBC headers meant for that car, cut off the flange, and weld on the LS flanges? I don't know the spacing between the primaries on a BBC, but surely with a little persuasion it would work. Anyone done this? What do you guys think about it?

topher455

iTrader: (6)

I think that is a viable option except the size of the primaries on a bbc header is usually 1 7/8 - 2" which is a little large for most stock ci ls motors

ramdaspadhye

iTrader: (3)

Well, jegs has a set of BBC headers for my application and they're 1 3/4"...

http://www.jegs.com/i/JEGS/555/30056/10002/-1

Only 90 bucks at that. Thought about getting some flanges and mocking it up to see how it would fit. Just trying to see if anyone else had done anything similar?

ramdaspadhye

iTrader: (3)

Anyone?

chevellepowered

iTrader: (37)

yep i was just searching that..
thats exactly what im going to do.. owell if there big.. $400 + for a set of headers is redicilous... wtf!!!!!,, im going to use sbc headers and cut them or bbc headers and cut them and buy some flanges. then match them up..

a big company should step up and offer an affordable header for lsx motors for older stlye cars.. cheapest ive seen is 498 dollars.. thats insane..... i can buy a set of bbc for 150 or less..

ramdaspadhye

iTrader: (3)

Those jegs ones are 90 bucks!!! As long as you use a flex pipe with them, they will hold up just fine. I do believe Im going to order them and fab them to fit!

ls1nova71

iTrader: (4)

I've seen it done with small block Ford headers, the spacing seems to be real close with them.

topher455

iTrader: (6)

Sorry it took so long to reply back. The only way I have seen it done is with sbf headers. I dont see why it wouldnt work though. Only thing to keep in mind is if the bbc is wider than the ls from one header mounting suface to the other. Then you may run into chassis fitment issues.

ramdaspadhye

iTrader: (3)

What SBF headers would clear in a GM fullsize car?

topher455

iTrader: (6)

My guess is Mudstang lt's. 5.0liter 79-93 I think??

S10xGN

iTrader: (11)

I did this in my Maverick swap (BBK Mustang 351W swap headers), once you cut the old flange off and test-fit the tubes into the LS flange, there's quite a bit of "wiggle room", especially in and out. I was able to move my collector 3" side to side and had 2" of "skew" before the tubes pulled out of the flange.

ramdaspadhye

iTrader: (3)

Can anyone verify that these headeres will clear in a 70's B-body?

NemeSS

iTrader: (127)

its hit or miss really, all thos sbf headers were designed for those vehicles chassis. if one side works, there is no gurantee that the other side will fit correct. of course shorties will offer better clearnace.
summit sells the truck shorties for 150$ iirc.
but if need lt, imo fabricating will prolly be the easiest way and least headaches. even if not good at welding,
find your tube routing and tack them when satisfied, and then take to welding shop for final welding. i made set once with odds and ends tubing and self made flanges on a lathe and bench grinder and drill press.
and had an arc welder at the time, so i just tacked them at home and then took them out to the shop and tig them.

ramdaspadhye

iTrader: (3)

Took my exhaust gaskets to O'rileys today and sure enough, the spacing isn't the same for a BBC. the BBC is spaced much further out. I don't think I'll have a problem mocking these up.

NemeSS

iTrader: (127)

About how much further is the port spacing?

ramdaspadhye

iTrader: (3)

Probably 1/2" to an inch on each port if you center the gasket. I will have to totally cut the primaries off the flange and collector in order to adjust the spacing. I may have to give the pipe some...pursuading in certain areas, but I don't think there will be much problem honestly. I can always shorten the length at the collector, which isn't a problem.

ramdaspadhye

iTrader: (3)

I'll post pics when I get around to doing this. It won't be for a while. Gonna use the manifolds to get it running, then I'll jump off on the deep end with the longtubes

topher455

iTrader: (6)

Might as well get a weld up ls1 header kit. I have seen a few on the net.

NemeSS

iTrader: (127)

i agree. it will save the hassle of trying to guess the measurements.
if u buy some headers and chop them up, theres no returning them if they dont work for whatever reason

kj598bbc

What year b-body, f-car headers fit 77-79 as told to me by KCHenry.