Need some advice on 1st lt80 top end build. I have all of the need parts and the cylinder had been honed. I am wondering if it is necessary to machine the inside of the cylinder head because the new piston is .040 larger than the old one ? The old piston would fit into the recessed area of the head. The new one will not, .040 over ?

Similar question on the head gasked. The stock piston and gasket had more clearance than what the .040 piston has with a stock gasket. THe piston will pass through the gasket but not much clearance.

My concern is whether the piston will contact the head or gasket and damage it ?

Any need to machine the head or by an oversize gasked with a .040 piston ?

Thanks for help.

 

You need to take your new piston and the cylinder and have the cylinder bored to the new piston.
The piston will not contact the head or the head gasket. What you have is good the way it is.
FYI: piston to cylinder clearance::Tell the shop that's doing the boring that::
Stock piston= .0025 (hopefully this is what you got)
Wiseco= .0035-.004
Arrow toward the exhaust.
Head nuts to 115 inch pounds.

Why did you get a 1.0 over piston? Was the cylinder allready bored .5 over?

 

Thanks for the reply Mr. Moore. I am using the 1.0 over because I purchased a cylinder and piston that were bored to match. I still have the original cylinder that I kept, now I have 2. One that i purchase .040 over and the orginal. I will keep the orignal as a spare.

So with a 1.0 piston and piston bored to match, am I understanding correct that the piston will not contact the head or gasket ? The clearances are much less than factory oem.

Also I have read much about shaving the head .030 ? Basically is that just shaving .030 thousanths off the head mounting surface where the gasket goes on the head surface ? Thanks so much. I want to be sure to tell the machine shop correctly what i need.

 

"am I understanding correct that the piston will not contact the head or gasket ?"
Yes, correct. Nothing will hit.

"is that just shaving .030 thousanths off the head mounting surface where the gasket goes on the head surface?"
Correct.