I have GMPP LS6 60.7 cc heads on my car and want to swap my FM11 which the specs are, 228/230 .591/.581 112 lsa. to a FM13 which the specs are 230/232 .595/.583 112 +4 lsa. on this particular one. I think it'll fit without clearance issues, but would like some other opinions rather than screw my engine up.

 

Measure that ****!

Do you have 2.02 or 2.055 valves?

 

Ben, I've got Stock sodium filled LS6 valves.

 

That ****'ll fit with stock valves.

 

I hope or I'm gonna get you to help me redo all my ****. I holding the S.A.M. student liable. Oh by the way I sold the Draglites for your Acura, LOL....

 

It's gonna be real tight , how much have the heads been milled? What you need to do is get the valve seat to piston clearance at TDC as measured with a dial indicator. Multiply the lobe lift at TDC by the rocker ratio of 1.7 and deduct that figure from the valve drop number and that will give you clearance at TDC. Claying is still necessary, as is checking clearance with a soft spring at 8* ATDC on the intake.

 

The heads have not been milled @ all. They are the 60.7 cc version, the block also has nothing taken off of it.

 

Damn you.

 

Something doesn't jibe here stock unmilled LS6 headsusing the graphite gasket give 64.4 CC. I'm putting in a CC 288/239 .588/.591 112+2 and only have .045 clearance at 8*ATDC must flycut.

 

GMPP sells the cnc LS6 heads with two different 64.4 cc, and 60.7 cc. If I have to flycut, then I guess I'll get to it.

 

All I know is when I cut the clay for measurement yesterday afternoon, I knew my new cam wouldn't fly without notching.I need piece of mind.

 

I problably will flycut.