Thread: Piston and valve clearance

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Originally Posted by Darrin Hammond

How much lift can I put into a LS6 motor. Compression has been lowered to 10.2:1. Running a spd with 26" tall tires. I would like to run a solid roller.

I don't think anyone can answer your question as asked, there are too many variables that we don't know. Assemble a head with checking springs on each end of the head and use a dial indicator on the retainer as you push down on the valve stem tip to find the points of interference (usually at overlap between the piston crown and the exhaust valve). Don't push on the retainer, you will unload the locks and disassemble the whole mess.

You want checking springs on each end of the head so you can determine if the block is skewed from front to back. (block decks not parallel with the main bearing bore). Snug a couple of head bolts down by hand, without head gasket. Then, you can add head gasket thickness to your clearance values.

Also, no big deal, but you have posted this thread in the BBC forum. The current/recent production LS-6 is a small block.

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