Generation III Internal Engine - Piston to valve clearance. Am I good?

Ok. So I didn't measure because from all my reading and comparing combos I thought I would be safe. It has been brought to my attention that I may not be.... Do you think I'm running it too close?

-Stock LS6
-230/230 .60x .60x 111+2 EPS/LXL
-2.02/1.57-60 @ ~61-62cc (bought them at 62cc and had them resurfaced, guy said he took just about "4" off, I'm assuming he meant .004)
-OEM MLS gaskets (.051 compressed I think)

Should be good, but I'd still measure

Heads are torqued and timing cover is back on. Ive got the manley nextech .690 springs, theyre pretty heavy, think its ok even if it's a little tighter than it should be (.070)??

One way to find out now....rev the hell out it and then pull the heads to see if there are any marks in the top of the pistons and bent valves....



I did have the proper clearance, close, but enough....when I pulled my heads to port them I had marks on the pistons from some valve float, but no bent valves...I got lucky.

If my math serves me right @ 62cc with the resurface that should put me in the .020 milled area, right?

One way to find out now....rev the hell out it and then pull the heads to see if there are any marks in the top of the pistons and bent valves....



I did have the proper clearance, close, but enough....when I pulled my heads to port them I had marks on the pistons from some valve float, but no bent valves...I got lucky.

Darn you. Lol

It's gonna be close on a 109 ICL with those big valves but there's really no way to say "yes it'll clear" without checking. If you're concerned with it but don't have the exact know-how on checking PTV, sell those heads and run something with stock valve sizing.

Contrary to internet expert belief (or marketing hype from certain parts vendors), bigger valves don't make much difference on a 346ci engine and often times lose low end TQ.

Good luck sir.

A set of $9.00 checking springs that you can install without removing the heads and a dial indicator $25+ are your best friend. You should always check.

A set of $9.00 checking springs that you can install without removing the heads and a dial indicator $25+ are your best friend. You should always check.

I this method better than clay?

Measure, measure, measure. Preliminary check could be to turn it over by hand. Stop when you feel it grab. This is the feel of a valve hitting the top of a piston. If it doesn't grab, this doesn't necessarily mean it's clear @ engine speeds, but, is a general indicator.

BTW, a valve contacting the top of a piston doesn't only potentially bend valves, it also can cock the rings in the bore, leading to bad ring sealing & lowered compression.

...so measure.

More accurate than clay. Simply turn the engine over until the needle stops moving and heads back the other direction, write it down, then push the valve down until it hits the piston. That's your ptv.

Ok, so I severely over simplified that, but that is the basics.