Yes and thanks to you and everyone else for all the suggestions. Still haven't found out the cause but all the help is very much appreciated. Anyways, I ran it without Valve covers. It's still there. I pulled the accessory belt off and ran it for a bit. Still there. AGH!

 

was the oil windage tray already installed when you got the engine,, if not did you check the clearance and shim it?

 

Ummm.... When the engine was built it was pulled the Windage Tray off of a wasted L76. Cleaned it up, and it was fine. Installed it on the engine. I have previously had the engine back out of this truck and looked at it for scarring when I tore it down. No Scarring or rub marks or anything weird like that.... That may be a probable cause because I never spent a great deal of time with it.

 

you usually need 3-4 washers under the tray to give it clearance on a stroker crank

 

I was all excited for a bit, but I took pictures of the bottom end during the build and I looked back through them. I don't remeber doing it but there are clearly 3 washers underneath the tray. I put a Stethoscope to it and it is definitely in the top end too. Like right underneath. That leads us back to Head Gaskets I suppose....

 

grrrrr Ive been there all frustrated and all! but just pull the heads FTFW and since its in the top, chances are its there. during the build did you loose a nut or bolt? that clip just sounds like an object getting tossed around in there.

goodluck man! im subscribing for the end result!

 

Thanks again for all the support everyone. I guess I better get cracking since I'm pretty well settled that it's below the Heads. If I don't find anything then yeah I guess Randy is right and it's Piston Slap. But man... Driving the thing around is almost embarrassing. The only thing that make up for it is that it runs like a raped ape. Hey on a ZR1 cam, are you supposed to advance or retard it in an install? Could it possibly be valves just slightly tapping the tip top of the pistons? The heads are milled 50 thousandths.

 

You're overlooking the fact that the factory cylinder bores are shorter than what you'll get on a block with aftermarket sleeves, therefore the there's less support at BDC for a stroke that long...

 

I did not overlook any fact. If you read what I wrote, it says nothing about that. A piston supposedly having a shorter skirt than another and that is what is causing the issue is not the problem because they are no different.

 

John your wording in your post is a little confusing. are you saying there is no difference in piston skirt between a stock stroke and a stroker crank? If so, that would be an incorrect statement as the pistons for stroker apps are much shorter and do lend to some of the inherent noisyness of strokers but this motor sounds like its got more than just regular stroker knock.

 

I did change it. I am comparing stroke to stroke, not bore. No incorrect statement there. We are not talking about stock anything in here really, so I have no idea how it could have been confusing in the first place.

 

The ZR1 cam is installed straight up in the ZR1 as they use all the same timing setup as any dry sump engine. The tolerances that GM allows can make that possibly advanced or retarded by 1 degree or maybe a little more. The timing set that you have is keyed for different advances. This one should be installed straight up as well. IF the set is set up to be installed straight up but you do not line the dots up perfectly, then the camshaft is probably now accidentally installed advanced. It CAN hit a normal piston being that far advanced, but with a 427, the pistons have very large valve reliefs in them. It should not hit them unless the camshaft is way overly advanced. Or even possibly retarded. The ZR1 cam has such low specs that it would be rather hard for this to happen IMO.

There will be a huge argument now about degreeing in the camshaft.

 

Ok, when I built it I made sure that things were dot to dot. So that's of no issue. I was just wondering. What about lifters too? Running 1249925's (LS7) Um, I've built old style strokers before that never made clatter like this. The pistons appeared to have no scarring on the Skirts but, I couldn't get a thorough examination. I've never heard ANY noise like this in any gasoline engine.

 

Bottom Line is. SHOULD I BE WORRIED ABOUT THIS?

 

yes , that noise is too loud,, my 415 stroker has very short skirt mahle pistons and it makes a little piston noise till the engine gets hot then it isnt very noticable

 

Those lifters are use on more camshafts than you can shake a stick at. The LS9 (and all LS engines) use that same lifter.

 

Ok wonderful. Thanks for the info.

 

John,

Your barking up the wrong tree, skirts have nothing to do with this. I included some references and built a drawing to show why. If you'll notice, with this long a stroke the piston is pulled so far out the bottom of the cylinder that it no longer matters if the skirt is 1" long or 6" long. Either way it's "hanging in the breeze"! In fact, the wrist pin is partially exposed, so whenever the crank goes over-center and starts pushing the piston back up the bore, there's only the ring pack and part of the barrel supporting the change in direction, no skirt at all.

Skirt length on LS blocks (3rd post from the bottom)

Stroker article (starts at page 3, read it all)

 

I vote pull the heads, check the gaskets and just cause the lifters are used on a lot of applications doesn't rule out that there could be a bad one in the mix. I'm really stuck on how "hollow" the sound bite sounds, it's not a solid knock.

 

This makes good sense! And I can vouge to say that when the Piston was at BDC and I had the motor upside down, the Skirt was poking way the hell out of the hole. Not sure if you could see the wrist pin because I couldn't **** my head that far into the block. Will this break a piston if used continuously? And why does it quiten down when things get warm? Yes things expand when they get hot but your stroke doesn't change.... So.... Where does that bring us?