RobZ

Well bought this motor to install last year on my previous car,but sold it and not till recently bought another car,replaced the ls1 with a lq4.I didn't even know it had forged pistons till I installed it lol.Well turns out as soon as it was started,it started tapping.My thoughts were well must be a lifter..So a 2 days ago pulled the heads inspected everything nothing unusual.Went off to buy new ls7 lifters,gaskets,etc.I decided to clean the top of the pistons a little and as I was cleaning the #1 piston it rocked left to right I was like this doesn't seem right.

So its my understanding that forged pistons need a little more piston to wall clearance?When engine gets to operating temp the pistons expands?My question is would the tap sound I heard be actually the piston or pistons rocking?Video I took sorry for the quality cell phone.

http://www.youtube.com/watch?v=xtZtwW4pElQ

tittan1500

iTrader: (8)

Ya thats way way to loose ! Rebuild that sucker, it probably has some major damage from running that loose

RobZ

Cylinder walls look good,Oil pressure was good,Also when engine was raised to 2000 rpm the sound fainted almost away.

chrisfrost

iTrader: (8)

Did You measure between that bottom ring land and the cylinder ? Pistons on the pin end sides only have that narrow part that is below the oil ring that is the same diameter as the skirt , the ring lands are between .030" and .050" narrower than the skirt and that narrow part below the oil ring on the pin end side . But that does seem a little excessive . Good luck fo sho .

SuperSport01

Did the motor tap when fully warmed up? The video makes it appear as though there is entirely too much PTW clearance. Measuring would end all doubts though.