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Hi everyone. I screwed up and slipped and my Lindy in block piston cutters took one of my 2006 gto ls2 flat top pistons to 0.185 deep.
I only needed 0.120 cut for 0.120 intake and 0.100 ex clearance w a solid lifter. Heads are milled 0.040 and I'm using a 41 gasket. All others are pistons cut to 0.120"max.its just the intake side on one cylinder. Exhaust is normal 0.120" i did not drill through. Fyi its all stock bottom end w original timing chain oil pump etc. I decided to drop 823 heads on it w a big cam. I've been told piston flat top wall thickness in that area is 0.177 thick thats obviously not true, i have heard its 0.250 thick.. and also 0.315" thick. Its definitely not uniform.
Ive attached pics of the suspect 0.185 intake valve cut and the std 0.120 cut .. ex. Valve is same on both. Also a view of piston bottom.my cousin is a racer and said this happens a lot and you will start to get smoke and hear a misfire then you have a chance to pull the motor and fix before the heads and cam injest metal so see what happens! any help appreciated and many thanks.
Over cut intake 185 deep, ex ok 120 deep.fyi this is before the hand blending and polishing steps. Std cut on all other cylinders.the gost has 100,000 hard miles. Ran like a top.
ive been told piston flat top wall thickness in that area is 0.177 thick thats obviously not true, i have heard its 0.250 thick.. and also 0.315" thick. Its definitely not uniform. Ive attached pics of the suspect 0.185 intake valve cut and the std 0.120 cut .. ex. Valve is same on both. Also a view of piston bottom.
my cousin is a racer and said this happens a lot and you will start to get smoke and hear a misfire then you have a chance to pull the motor and fix before the heads and cam injest metal so see what happens!
any help appreciated and many thanks.
Last edited by twistedneck; 09-14-2018 at 07:51 PM.
Reason: pics
Whats the cost of a single piston? If you are worried, swap it out.
good point. I was over ruled so i hope to the gods that its in a thick spot what ever thick is ?? For hyoereutectic pistons they dont expand too much. No bottle or boost.. is there hope?
The only way to really tell how safe it is would be to pull the piston and measure thickness. .060 is a lot though, even if it's .250 that's only .065" thickness. Not to mention what's going to come out additionally once the hand-blending starts.
The only way to really tell how safe it is would be to pull the piston and measure thickness. .060 is a lot though, even if it's .250 that's only .065" thickness. Not to mention what's going to come out additionally once the hand-blending starts.
For the cost of a new piston, I wouldn't run it.
i blended the corners only and was so paranoid only did a careful job so they are not blended as much as softened in the corners.
one thing is true we are going to find out since its going back together. The risk is real high for sure.
You'll have slightly lower compression on that cylinder.
the over cut piston beast lives! seems ok for now and runs like a champ - smooth and pulls very hard until i am scared and shift at 6700. does not roll over at all there but seems perfect so limiter is set to 6800rpm.
After a full season of hard driving, lots of max effort blasts, highway runs to 150+, many many many races - no issues at all with 0.250 deep fly cut on the piston. Must have got very lucky with the placement of the max cut depth. Valve sizes are stock LS3. I hope this helps any poor fools like me in the future..
09-14-2018, 06:35 AM
Ls2 gto piston thickness (fly cut too far) help 
