SMaXMan121

Would you resurface the exhaust manifold which has an exhaust leak, before installing its new gasket and new bolts or not ?

bww3588

iTrader: (49)

most definitely. don't take off an insane amount, but enough to get it true again will not hurt at all. any good machine shop should be able to mount it up in their head mill and take it down for you.

SMaXMan121

thanks for that buddy !
We don't here much about exhaust manifold machining, other then porting.

Is it common or not ?

bww3588

iTrader: (49)

you wont hear much about it around here on ls1tech simply because most exhaust manifolds end up in the scrap pile for a set of headers. however, in my experience at machine shops, it is very common practice. esp for people that are doing stock rebuilds that take the manifolds off and they end up warped.

not sure if your familiar, but on old school small block chevy's, it is common for the need for a manifold spreader to re install the exhaust manifolds because they warp so much after removal. same applies to LS manifolds.

SMaXMan121

thats good info.

First time I heard of the spreader, I guess the issue there is the poor webbing reinforcement between the ports.

While we are talking about exhausts, is is worth porting a stock LS1 head and manifold ? Is their any real gain in performance ?
Thanks again.

bww3588

iTrader: (49)

Head is worth porting, and a gasket match on the exhaust manifold won't hurt any. If you have a 01, the manifolds are actually very good in stock form, and if you have a 98-00 its worth it to move up to an 01 manifold.

Extrtde honeing is an option but I think price out weighs the benefits.

bww3588

iTrader: (49)

I should have worded it better about the ls manifolds warping. They can warp along the plane surface, but I haven't seen them warp latterly to the point the bolts won't go back in like the old small blocks. But I have seen them warp where they won't seal totally.