Im thinkin of getting the 02 Z06 Cam and the base circle is .050" smaller. I have 2 options. Using a 7.450" pushrod over a 7.400" or milling the heads .025 - .050" and using 7.425" - 7.400" pushrods.

I was leaning toward the 7.400" pushrod and .050 milled head, but should I flat mill it or angle mill it? Another question is what would the compression ratio be with stock head gaskets and stock length pushrods. I was thinking around 11.1:1 but I could be wrong. If someone could help and maybe give me the exact compression or an estimate Id appreciate it. Its a 98 LS1 with 241 LS1 heads. Stock for now.

Will run 93 octane, i was running 12.1:1 on my LT1 heads with no detonation.

 

Ok, im alittle confused. Seems the LS6 cam is .050" in difference in base circle, meaning youd have to make up .050". People are getting away with 7.400" pushrods and most are using 7.425" pushrods. Wouldnt a 7.450" pushrod be a more exact fit and give you the most power you can get out of it? Id be going a diff route, itd be the diff between an .030" mill to a .050" mill. .030" would work but would .050" be best if the compression is lowe enough? I seen some LS6 cam kits and they all come with 7.450" pushrods.

 

so would that be a .025" diff on each side, instead of a 7.450" pushrod Id need 7.425" pushrod or mill .025"-.030"?

 

For absolutely dead nuts perfect valve train geometry and lifter preload you should go with the 7.450 with the smaller base circle cam and stock heads. If you mill the heads then you should shorten the PRs the amount of the mill. .025'' mill/.050'' smaller BS cam would be 7.425'' PR.

 

.050" mill on a 241 head would put the chamber volume right around 59-60cc. With a stock gasket, deck height (remember LS1 pistons come out about .006"), and pistons you should be around 11.4:1, which is fine on 91 octane or better. Just remember in the future any cam bigger than the LS6 will most likely not have enough clearance from the mill.

Flat mill the heads. .050" is about the max that you can get away with on a stock intake manifold and port seals. You may want to use a thicker aftermarket port seal just in case.

 

Thanks for the input. I have been told that its a .050" diff in the dia so that means a -.025" on each side, meaning youll only need 7.425" pushrods or mill the heads .025". 7.450" pushrods would put it over .025" on each side........ maybe people misunderstood when they put the 7.450" pushrods as I did.

 

I see it as an overall .050" difference and being .025" difference on each side as illustrated, meaning a 7.450" pushrod would actually be .025" too long on each side.

 

Honestly I wouldn't waste my time with guessing on the pushrods. Measure it. With the LS1's non-adjustable valvetrain, the pushrod length is much more important than with the SBC stuff. Too many people go too short and end up with all kinds of issues, the "sewing machine" noise being the primary problem.

 

Another member is running the same setup Im wanting to run but with a .030" Milled head and 7.400" pushrods. He's done it on many cars and he measured his with the checker and it came out only .025" off but he did the .030" to gain some extra compression.