1slow01Z71

iTrader: (36)

Im rebuilding a stock LQ4 for a friend and Im concerned about having a noisy motor. Ill be getting the block honed which Id imagine will take out .002 or so, and going back with stock pistons and not an oversized piston Im afraid Im going to have a noisy motor atleast on initial start up. Ive never built a motor with sotck pistons, theyve always been forged and each cylinder bored per piston manufacturers recommendations. So those who have rebuilt stock shortblocks do you get excessive piston slapped?

1slow01Z71

iTrader: (36)

Nobody?

CCF1000

iTrader: (1)

I'm curious about this as well, thinking about building a 6.0 l myself.

defdaboss

good question..

ttt...

O2Form

Well its very simple measure the bores then measure the pistons...if they are within specs you can use them. If not you need carefully match the pistons to the bores. If you remove .002 I can tell you right now you can't use the old pistons. Why not check your pistons now and see how they measure up. Maybe you can get away with a quick ball hone?

defdaboss

whoa.. when u hone the block ur cutting it to make it slightly bigger? i done it before in school and at the time i thought it's just to clean the cylinder.

1slow01Z71

iTrader: (36)

To clean the piston skirt scuffing out of the block a hone job takes .001 to .002 out of the cylinder according to my machinist. Thats why I asked the question since Ive seen multiple people rebuild engines with stock pistons but some seem to have pretty good piston slap to them but I dont recall ever reading on ehre of someone complaining about it. Just seems they come fromt eh factory set right then when you hone them youre taking a little material out and according to my machinist its .001/2 which would take it out of spec for piston to wall clearance.

O2Form

I don't think a quick ball honing will remove that much material. The hell with the piston skirt scuffing......how long do you think it would be gone for if you are reusing the same pistons? I mean seriously wjhat are you trying to do?

I would measure the pistons and bores as they are.....this will tell you where you are size wise. If you are ok and going to reuse the stock pistons do a quick ball hone and move on.


Personally if it were mine I would measure the bores and see how much attention they need THEN buy a new set of pistons set up at the min clearance. AND PLEASE REMEMBER you don't double the clearance reading on the piston! If it calls for .003 that means the bore is .003 bigger than the piston NOT .003 all around the piston.

I just read a thread where a guy had his engine rebuilt and the machine shop fit the pistons with double the clearance because they actually thought it meant all the way around the piston. I know its insane to mention but it happens all the time.

LSXKE20

Ive had piston skirts ceramic coated which adds around .001 - .002 . This is an easy way to stop the ls piston slap issue on the cheap. Cost $180 here in Aus. You can then tighten the bore due to less friction.

Fastdriver1992

iTrader: (1)

i've melted my #4 piston on my SBC 3 times, each time i did a quick clean up hone. swapped the piston and rings and its still running strong with no noise what so ever making 850 horsepower on 15lbs of boost...

chrisfrost

iTrader: (8)

Sm block Chevy's have a larger piston to bore than the LS based gen 3's n 4's do . The LQ4's piston to bore service limit is .0028" and production is .0009"-.0012"

chrisfrost

iTrader: (8)

Don't know why You would coat the skirts with ceramic ,,,,,,,,if it were Me I'd coat the skirts with a dry film lubricant . the tops of the pistons and the combustion chambers and the exhaust ports would benefit the power #'s if coated with ceramic and the engine would not want to warm up with all that ceramic so a considerably smaller radiator would be in order .