unknown_host

iTrader: (1)

What head gaskets do you guys recommend for someone swapping a set of Vortec heads onto a stock L98 short block? I will also be running an LT4 cam (or similar), and am hoping to make 350-400 horsepower.

Thanks!

86LG4Bird

iTrader: (1)

With that hp goal, I have to assume you're talking LT4 Hotcam and not LT4 production cam. With that said, you need all the compression you can get with the stock block deck height, so run .015" steel shim gaskets. Check block and head decks for flatness!

unknown_host

iTrader: (1)

Yeah LT4 hot cam is what I am looking at. The stock heads are 64 cc and my stock compression ratio is 9.3:1. 218/228 @ .050 with a 112 lsa isn't that big for about 9.5:1 don't you think?

I could also mill the heads down to 58 cc, I just don't want to run into any piston to valve clearance issues.

So your suggestion is shim gaskets? I had concerns about running them on a high mileage motor, mostly the block being flat, do you think it will be an issue?

VincentZ28

iTrader: (2)

Thats the type of gasket that is on stock motors with cast iron heads except not as thin. Go with the gasket he mention. The compression will be up to 10.5 and it will be ok. Just get a good tune in the chip.

86LG4Bird

iTrader: (1)

Are those dished pistons in that L98? If so, you're looking at about 9.5 CR with .015 gaskets and 64cc chambers, which is not enough for the Hotcam. I'd mill them to 58cc or less, still run the .015 gasket for good quench, degree the cam in at a 106-107 ICL, not the 109 that it normally "drops in" at, and you'll get a better overall power curve.
Yes, the stock L31 Vortecs use a .026" steel shim gasket.
No, you are nowhere near piston-to-valve contact with that cam, no matter how thin a gasket you run and no matter how far you mill the heads (at least to the point just short of destroying them )