hamood91

hi guys

Im doing rebuild to my 2005 LQ9 Engine but im keep stock bora size and stock piston.

for psiton ring should i reuse the old piston ring or buying the new but if i change the rings which size should i go and how much gap it should be

A.R. Shale Targa

iTrader: (2)

If you have ANY history on the engine, most leave the factory short block together and just toss a cam and heads on it. GM designed these for 250,000 miles. In my experience, loosening the rods and re torquing them does distort the shape of the big end and some have ended in bearing failures. If replacing the rod bolts, a competent machine shop can simply hone/resize the big ends and still keep them within spec.
On your ring question, what are you doing with the engine ??? Blower, turbo, nitrous or just old school naturally aspirated???
With the standard GM 4.000" bore a .018" top ring gap and a .026" on the secondary should set you up decent for most applications

TheZ346

DO NOT take the short block apart if you aren't going to have the block machined and put fresh bearings and rings in it. New rings really need a fresh hone to seal properly. if its being honed you need to put at least a .005" over piston or you will have excessive piston to wall clearance.