I have been talking to a guy about a built ls1 with forged bottom end and he said it has a little piston slap. Is that normal even with the after market pistons? I know is pretty normal with the stock ls1s. Should I stay away from it?

 

i always heard that with forged pistons that they always did have piston slap on start ups

 

Very normal. All the ones Ive heard do. Do you know what pistons are in the engine?

 

Probe pistons are in it

 

I don't think they fixed the piston slap issues until the ls2/3...I could be wrong though

 

My question is will a forged bottom end ls1 still have piston slap on cold start? Or is this normal? I have build some engines but never ls based. From what I understand the piston slap is caused by there being too much clearance between the piston and cylinder wall of the block and GM no actually measureing and matching pistons to bore size. Wouldn't that be solved when some one adds after market pistons if the short block was built correctly? Or is it just a problem with the aluminum blocks?

 

i would think a rebuilt one wouldn't have it

 

I have a forged 346 with Probe pistons and yes I have the slap. Right now my car is over at Speed Inc. getting Weisco pistons because the Probes are complete garbage. I would never have choosen them except that the a-holes who originally built my engine told me they were putting in Diamonds. Once the engine is rebuilt with the Weiscos I will let you know if I still have the slap. Most likely you will always have more noise with a forged engine because the materials are harder and less forgiving so I think it will still be there.

 

I have the Weisco...There was never any slap. The Weisco were specifically designed to eliminate piston slap.