piston to wall clearance ?

triton

triton

Scarlet Fever
Joined
May 30, 2007
Messages
5,497
if the piston manufacturer is calling for 0.002 clearance to the cylinder but, there will be 0.004 clearance..... how will that affect anything if at all ?
 
yes. I was told it could make a lot of noise with the extra room ??
 
4 thou is fine. Had my first set at 7 thou and they sure was no piston noise. 3 thou is as tight as I've set them up so far and they still didn't show any evidence of being tight.
 
Depends on it's application, a bit more PTW wouldn't be a concern if it is not mainly street driven.
 
I guess then if it is mostly street driven it should be as tight as can be ? Will the rings compensate enough for .002 more than suggested ?
 
seems .002 more isn't too bad for a street driven truck. I wonder if the rattle my truck used to have could have been attributed to the clearance cause it was built very loose. Nothing else was ever found?? They were stock pistons.
 
triton said:
seems .002 more isn't too bad for a street driven truck. I wonder if the rattle my truck used to have could have been attributed to the clearance cause it was built very loose. Nothing else was ever found?? They were stock pistons.
Click to expand...

How loose is very loose?
 
I run them at .0035 without an issue. After ~12,000 miles, no sign of piston rocking. No noise from it either. I find it hard to believe you would hear piston slap at that clearance. I think it more likely you would hear the wrist pin. It comes out of the box at .0035 on the monotherms. You would only hear that when it's cold though. Monotherm's wrist pin clearances decrease as the engine warms up, where stock piston's wrist pin clearances increase with engine temp.

Ty, I do not think that the noise you were hearing has anything to do with the monotherms. From my experience the monotherms run just as quiet as the Cummins pistons do.

I think the bigger issue with running large pw clearance with monotherms is cylinder wall loading. IMO .004 isn't a problem. .007 or more and cylinder wall cracking becomes more likely.

Paul
 
paulb said:
Ty, I do not think that the noise you were hearing has anything to do with the monotherms. From my experience the monotherms run just as quiet as the Cummins pistons do.

I think the bigger issue with running large pw clearance with monotherms is cylinder wall loading. IMO .004 isn't a problem. .007 or more and cylinder wall cracking becomes more likely.

Paul
Click to expand...

Thanks Paul. I was referring to my last motor which had the crazy rattle. It had stock pistons. A sled puller designed the specs for that one and I know he left them pretty loose.
 
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