Valve clearance???

[RICK]

Not looking for valve to head clearance,,,,,, I just set a late corvette LS-7 head on a6.0 block, and the exhaust valve 'kisses' the cylinder wall.  I know I can use off-set dowels to slide down a bit, a smaller exhaust valve, bore the block, or even cut a relief in the bore, like they used to do on the  big block chevys. I'm just not sure what the recommended valve to cylinder wall clearance should be?

   Thanks,  RICK

[nrhs sales]

How close are they to not touching? If they are just "kissing" could you not just angle cut the valve head a bit to clear?

[RICK]

With the head installed, I can push the valve down and hear "fingers on the chalkboard".  To Bore .030+ will give clearance, the question is will the .010 or so be sufficient for valve to cylinder wall clearance?

[nrhs sales]

I would just do a reverse angle cut on the top of the valve head so it just clears.

[saltfever]

Depends on how tight your guides are, the valve material, and the diameter of the valve. Assuming a 1.9" diameter, steel valve, it will grow about .007"-.008" from heat expansion. (based on the CTE of steel). Then add some clearance due to wobble from guide clearance (or measure your wobble). Add all those tolerances up and give yourself about 0.010" more. Different materials, different diameters, equals different results. YMMV