Piston slap

[AMXguy]

 My rebuilt 383 now has about 1000 miles on it and I have a forged piston slap question. when it's cold you can hear the piston slap which I know is normal for forged pistond ( Ross ) but even when its warmed up at an idle you can hear it if you listen close. is this going to lead to problems down the road do to an oversize bore or is this normal? at 500 miles a year maybe I'm worred about nothing?

[Chryco Psycho]

It depends how well the pistons were fitted , if it is loose enough in the hole it can cause problems

[Mopar73340]

Thats a new one on me that forged pistons make noise as I have forged pistons in one of my 340's and there is no knocking or SLAP noises. I would guess you have to much clearence.

[AMXguy]

Unless things have changed a lot these days I'd be more worried about no cold enging piston slap than too much, forged pistons expand enough that without a little extra room they'll scuff when hot. I just don't remeber ever hearing them at all once the engine is warm though.

[Oldschool]

Forged pistons do make a little more noise than their cast counterparts, but it shouldn't be annoyingly loud.  They also make more noise when cold.  Here are a couple of easy checks you can do to try and narrow down the source and possible simple fix.  First, use either an engine stethoscope or a simple broomstick handle and press it against the block (up and down both sides) and hold it against your ear while the engine is idling and try and isolate the source.  It could be coming from somewhere else. (Windage tray contact, oil pick up tube contact, etc  ) Sometimes forged pistons will make a little more noise if the timng isn't quite right.  Fiddle with the timing and see if it quietens them down a little bit. Also, what grade fuel are you running?   You could try a little racing gas also and see if that helps.   Just a couple of cheap easy things to try................           

[AMXguy]

 Good idea, I'm just guessing it's piston slap because it almost goes away when it's warmed up and only noticable at an idle. no more miles than it will ever get it probably will never matter, I just need something to worry about .

[AMXguy]

For anyone who cares I called Ross and told them what I had going, they said it might be a little lose but that's better than too tight so turn the radio up and ignore it. he said  even noticable warm idle slap won't hurt anything even down the road. I'll play with my timing some a little though I can see where it might help.

[moper]

Yup...Ross likes them run a little lose. I havent had anny noises, but they are generally .0005" bigger in recommended clearances than other forged. So if your guy was one thou off (it happens...) then they might be a little loud. If you dont have a really tight quench, no problems.