gpr

iTrader: (6)

When running .040" won't that put the piston to head clearance really tight?

what is a safe and acceptable squish clearance on these ls1's?

ISU-WS6

From what I've seen, people prefer between .030 and .040 for "optimal" quench clearance. LS1 pistons pop up out about .008 usually. I'm starting to worry about PTV clearance on my setup if I use a .041 gasket and have the 243s clean up milled about .003 or so.

nastybuzzard

iTrader: (2)

I am subscribing because I will also be building a LS1 up soon using stock 243 heads but w/ yellow springs and the 7.4 hardened pushrods. I haven't decided on a cam yet, the cam I was running, ASA, was smacked when my #6 piston/rod snapped.

Robert Cantu

iTrader: (2)

Yup that's what I got and hit em with copper gasket spray and be done!

A.R. Shale Targa

iTrader: (2)

Old school iron block apps were considered tight @ .038"-.040"
The aluminum LS blocks are fine with a forty gasket and eight positive deck
On the Pistons at room temp because the alloy expansion causes the .032" quench to grow at operating temperature

ISU-WS6

Some guys on here run their quench in the .020s, which is getting dangerously close. Those are usually very specific builds tho, and its not recommended for an every day, DD kind of car.

ISU-WS6

Bump for more input.

ISU-WS6

Bump.

AINT SKEERED

iTrader: (2)

So i have an lq4 . Would my iron block be better off with a .045 cometic?

RideRed0331

I'm also in the process of having a set of 243 ported/milled. I'm running a 228/232 112LSA cam in my LS6, and am worried about clearances. I would like to avoid flycutting at all costs.

With a .020 mill, will a .040 gasket keep me in a safe zone?

Ideally that should leave me roughly a 62cc chamber, I believe, which I will be running 93 octane pump fuel with.

juniorssrollin

iTrader: (1)

With a .020 mill, its going to be close. I would only go .010.
I'm running Tick SNS 3 with 243 heads milled .010 and 2.02 & 1.6 valves and I'm at .088 of clearance on exhaust valve with a .051 head gasket.

RideRed0331

Noted. Thank you. How big is that cam?

speedtigger

iTrader: (16)

If the cam is on a 110 intake centerline, you should have in intake valve open at 4 degrees BTDC and and exhaust valve close of 2 degrees after top dead center. With those valve events. .020" off the heads and a .040" head gasket, the numbers in my head say you should have about .045" piston-to-valve on the intake side and about .065" piston-to-valve clearance on the exhaust side. But, just like anything, it is your job to make sure.

I often use this calculator when trying to project piston-to-valve and I find it to be amazingly accurate: http://www.pcmofnc.com/index.php/com...nce-calculator

RideRed0331

Thank you, that's a very handy tool.

If I'm going to be that close I'll likely stick to a .010 mill and .040 gasket. I can deal with a few less points of compression for the peace of mind it brings.

Thank you for the input!

ISU-WS6

I didn't know anyone made a calculator for PTV clearance. I'll have to use it when I'm on an actual computer.

RideRed0331

Same deal here, never even knew about it. Next step is figuring out 1.) how to use it and 2.) to trust it!

juniorssrollin

iTrader: (1)

234/242 615 & 612 with 111+4

RideRed0331

Thanks, that's much bigger than I'll be going. I bought my Z06 with the current cam already in it, and was considering a larger setup at some point but am not yet sure if I'll be going that route. I want to stay conservative clearance-wise in case I do, though.

speedtigger

iTrader: (16)

"Trust but verify "

ISU-WS6

I attempted to use that calculator, but since there's no full specs of the ASA cam, I can't make it work. They only show the .050 durations, and the lift and LSA. I guess I'll just have to measure