Generation IV Internal Engine - stock ls3 valve springs max lift
06-12-2012, 02:39 AM
just a quick question
how much lift can the stock springs handle before the bind up?
i know i should change them out to some patriot's but a head swap is coming up son so i would rather wait
the cam i have chosen has 590 lift
and ill be fitting the new head out with 1.85 ratio roller rockers
06-12-2012, 04:09 AM
Assuming your cam is spec'd for 1.7 rockers, it has a .347 lobe lift...which puts you at .642 valve lift with 1.85 rockers.
You will need dual springs. Ls3 springs are good to between .500 and .525 depending on the lobe design, duration, ramp rates and other things.
06-12-2012, 04:10 AM
Why 1.85 rockers?
06-12-2012, 04:13 AM
ok so i wont bother trying cam only while i wait for my heads then
cam is a 224/232 580 591
any ideas on power ??
06-12-2012, 04:15 AM
as for the rockers i was thinking they will give me more lift and faster opening of the valves
like a more aggressive lobe
06-12-2012, 09:00 AM
No. That cam is designed for stock rockers. What little you gain with the 1.85 rockers will be offset by valvetrain instability, reduced spring life and lower compression ratio.
I don't know your entire build, but it sounds like you need to do a little more research before you start buying parts.
If this is going on a stock, ls3 short block, .642 valve lift on a 2.165 valve is not going to go well together. That valve is so large, you quickly run out of real estate between the piston and valve.
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