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How much lift causes piston clearance issues on LS6 engines?

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Old 04-25-2004, 09:47 PM
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Default How much lift causes piston clearance issues on LS6 engines?

Obviously, I will need to check clearance, but what is everyone's experience with lift numbers using non-flycut heads, OEM gaskets, stock ratio rockers?

What is "safe"?
Old 04-25-2004, 09:52 PM
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Not so much lift but duration and v.e. (valve events) are the contributing factors. Someone correct me if i am wrong
Old 04-25-2004, 10:09 PM
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Lift is not the problem, its the valve events that determine the clearance.
Old 04-25-2004, 10:22 PM
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imagine a cam lobe...its like a hill...haha

now it is not soley the highest peak on the hill that is important...its how long the slopes stay high enough to keep a valve open before/after tdc that effects if a valve will hit a piston...

you could have a .625 lift if the cam lobe rised and fell quickly enough so that it didnt keep the valve open around tdc...

look at the trex...is will fit with stock heads and has LOTS of lift and duration...but the lobes rise and fall quickly enough at the right time...

Old 04-25-2004, 10:27 PM
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Good points.

Valve dia probably effects it a lot also.

How much clearance is safe?
Old 04-25-2004, 10:29 PM
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Originally Posted by McRat
Good points.

Valve dia probably effects it a lot also.

How much clearance is safe?
.08 inch intake...
.1 inch exhaust...

im pretty sure im remembering correctly...
Old 04-25-2004, 11:01 PM
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I guess I'm going to cross my fingers and order tomorrow.
I've never done just a cam, or H/C before. All my experience has been doing complete motors. Just a little worried I might not end up with enough clearance.
Old 04-25-2004, 11:44 PM
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Originally Posted by McRat
I guess I'm going to cross my fingers and order tomorrow.
I've never done just a cam, or H/C before. All my experience has been doing complete motors. Just a little worried I might not end up with enough clearance.
as long as you use stock gaskets and don't mill the heads you should be fine...

if using stock heads you should be fine...
Old 04-26-2004, 12:56 PM
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How much can you get away with on milled heads? I'll be running a comp 228 grind with about .560 or .580 lift. All of this on a '98 motor with '98 heads that have been milled a little bit.
Old 04-26-2004, 08:33 PM
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Originally Posted by GTA91
How much can you get away with on milled heads? I'll be running a comp 228 grind with about .560 or .580 lift. All of this on a '98 motor with '98 heads that have been milled a little bit.
you should check every cam to be sure, but if your going to run milled heads be SURE to check...




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