When I bought my LG headers I read Lou's advice about using a factory LS1 gasket instead of the paper/fiber pieces that they send with the headers and of course NOT using the Z06 gaskets due to the different port shape. I ordered a set of the LS1 gaskets from my dealer and when they came in they were the same oval-shaped gaskets that were already on the car. Because it was decent weather in New York and I had the car all apart and wanted to get it back together before the weather turned to crap again I installed them with the gaskets Lou sent with his headers rather than waiting for the dealer to get another set with the round ports. Now I'm wondering it that decision will cause me troubles. I bought a set of LS1 gaskets from another Forum member recently and they, too, are made of the paper/fiber material. Yesterday when I was cruising around on LS1speed.com looking for parts for my bro's Trans Am I spotted the metal round port LS1 gaskets. Now I'm wondering if I should plan on buying those and installing when Spring arrives. When I finished the header install and started the car I had no codes and no leaks around the headers, so at least for now all appears to be okay, but......Any suggestions/experience with this gasket issue? Thanks!

 

i did the same thing 2 weeks ago.i'm having the same weather as you.i put my lg's in and i also ordered my gaskets from the dealer and ended up with the same gaskets as were on the car[03 z06].i used the gaskets that came with the headers because it was going to snow the following day.the only thing i did different was use locking header bolts[i got them from ecklers],i torqued them down[middle-out],let the gaskets set,retorqued them,then locked them.same as you,no leaks,faults,etc. but we will see after a couple of runs[if the dam snow stops!!!!!]

 

Do you have a part # for the round shaped gaskets? I assume the stock manifolds are oval and the LGM's are round?
Thanks in advance

 

I picked my new GM gaskets up last week for my LG headers. I told the parts guy I wanted gaskets for a 2000 vette. Part# is 12558573. They have the round holes.
You may not know they are leaking until after you remove them b/c the leak is small. I presently have a leak at the rear of my car where the catback bolts up but, the only way I know it's leaking is because I can see there is black soot on the bottom of the connection. Definately can't hear it leak but, you can see it.

 

I reused the stock bolts. I might try the locking bolts. I guess what I'll do is wait for Spring, drive the car for a few nice, long runs to get a few heat cycles in the headers and then recheck everything. I had a heck of a time getting the headers on and getting the bolts into the flanges on the underside of the bell housing, but I'm told that after the headers are heated a few times they'll "form" some. I want to let that happen before I start taking the bolts out to replace the gasket because I don't want to go through that process again as they are now! I'll probably end up buying the metal gaskets and replacing the gaskets that are on it now.

 

When I did my instal I ordered a gasket kit from GM. (I did my heads and cam at the same time). The kit came with both types of gasket. Kaley

 

Thanks for that part #, I'll order them tomorrow.
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