71Vent

Hello all,

I searched and can't seem to find the answer. I have a 2002 LQ4 and would like to upgrade the rods and pistons. Can I run rectangle port valve reliefs with 317 heads?
Thanks for the help!
Bill

brandon6.0

iTrader: (32)

I wanna say a 6.2 is a 376ci. A 6.0 is a 365ci with a 4.00 inch bore. A 6.0 bored .30 over is a 370ci.

So u would need to be bored a lil over .60 to fit 6.2 pistons in a 6.0 block.

71Vent

Thanks for the reply. I've seen some 6.0 pistols with l92 reliefs. Will the relief be in the same place or work?
thanks again

NEstyle

iTrader: (1)

There were 6.0s with L92 heads, though. G8s and Caprice PPVs have them.

A.R. Shale Targa

iTrader: (2)

LY6. IIRC
And an LQ4/9 would need to be bored .065” to fit LS3/L92/LSA sized pistons. Apparently most iron 6.0 blocks can go that far but sonic checking the cylinder thickness is a great idea before machining

71Vent

I'm trying to ask if I can use 6.0 pistols from an engine that uses rectangle reliefs with 317 heads.

A.R. Shale Targa

iTrader: (2)

Same 15 degree valve angle and you’re asking if pistons having reliefs designed for 2.165” intake valves will clear heads that use a 2.0” intake valve ???

ben42391

iTrader: (1)

i dont believe this works

clinebarger

L92/L99 pistons have a relief for the Exhaust Valve, Not the Intake Valve. The only reason for the relief was for VVT. LS3 pistons have no reliefs.

I don't see why you couldn't run 317's with L92 pistons unless your cam is pretty radical & the PTV clearance is getting close.....In that case you would need to fly cut just about any GM production piston.

A.R. Shale Targa

iTrader: (2)

So the LY6 slugs is what you're wanting to use....
As mentioned; apparently the reliefs are for the VVT exhaust clearance and not the intake as I had thought
Most LS3 guys can cam with a 230-232 @.050" intake lobe and still clear the 2.165" valves with the factory "no reliefs" pistons
Using the 2.0" valved 317 head castings you should be good as well if keeping the intake lobe around the 230-ish

71Vent

Thanks for all the replies. It makes sense if I use a cam that doesn't require reliefs that it won't matter.

another question.

I thought I read somewhere the older short 6.0 cranks are weaker than the gen 4s. Is this true?