C4vettrn

My new 383 with about 500 miles on the motor started making a slight knocking sound under the front of the motor. I don't get it until the motor is warm and is only noticable at idle. Are stroked motors with forged pistons known for any piston slap? I have plenty of rod and piston clearance on the block. Also it only seams to be coming from the very front and also seems to be coming from the bottom of the motor. Any thoughts? I just got this thing running good to, this is realy got me worried

PLRX

Tell us about the timing chain

If you installed the double roller, did you installed the new water pump gear set?

leesvet

Not that I've ever heard about...typically thats why we have forged pistons, to withstand some abuse that the cast aluminum will not.

Mine also has a noise thats not a knock, more like a rubbing or bumping that comes and goes...in the bottom, except toward the rear. Can;t hear it under the hood, mostly in the cabin at idle. Gone the next day, and cannot pin it down.

My thoughts are crank run-out. I can;t prove it without pulling it apart, but thats the only thing that makes any sense...the crank floating back & forth in the bearings and main seals . Its so mild and intermittent that its hard to justify deeper examination.

Is this possible with your new build? Crank run-out gets overlooked sometimes.

383vett

Piston slap usually happends when the motor is cold and the piston to cylinder wall clearance is at it's greatest. Knocking when warm can be bearing noise when oil viscosity decreases. Stroker motors shouldn't be any noisier than standard stroke motors unless the block wasn't clearanced and the rods are contacting the block or if there is an internal mechanical problem.

C4vettrn

Yes I have a double row that had lots of clearance issues but I couldn't feel any issues when turning it over by hand after I and cleaned up the bad spots. I have a 92 block with upgraded distributor and an electric water pump. If it was a bad bearing wouldn't it do it all the time i.e. when cold?

C4vettrn

Yes I have a double row that had lots of clearance issues but I couldn't feel any issues when turning it over by hand after I and cleaned up the bad spots. I have a 92 block with upgraded distributor and an electric water pump. If it was a bad bearing wouldn't it do it all the time i.e. when cold?

C4vettrn

Ok I just did the old wooden dowl rod as a listening device and it's definately coming from the bottom of the chain case cover and within. I hope it's only a timming chain clearance issue, the only problem is I would think if the chain was hitting it would be a more continues noise wouldn't it? This noise has the timming of the crank revolution "if that makes sense".

PLRX

Use the search, there are plenty of threads on how to shave the timing chain cover using a carbide bit.

STL94LT1

When I first installed my double roller chain there was a slight clearance issue, didn't sound anything like a knock.

383vett

Cut open you oil filter to see what's in there. If it's a bearing knock, you'll know quickly.

C4vettrn

If bearing clearances were good on install what would be causing this? I have great oil pressure but I noticed at idle there doesn't seem to be any oil laying in the heads or valve covers until the rpm's are brought up?

Would the metal in the filter have a certain look compared to metal from the timming chain rubbing or somthing?

C4vettrn

Ok I changed the oil and opened the old filter. What is the telltale sign of a bearing failure? I don't see anything gleaming, there are some small slivers that seem almost like aluminum other than they are whitish in colore and don't seem magnetic either, could this be a coating on the bearing?

coupeguy2001

my left catalytic converter brick fell apart when I high centered, The brick pieces are in the muffler, and it sounds like a diesel. Only inside. outside, it sounds like a little guy with a precisely timed hammer.
BTW, the right brick bounced around enough that it was like sand. The cat housing was empty. nothing but the air pipe.
I just had bullet cats put on it Wed.
and it's a 383 that sounds like there's noise coming from just under the plenum.
Been there since I first fired it up on the run stand, and I took the entire intake off, and checked everything out, but couldn't find anything.