I have a 95' Camaro Z28 LT1 383 M6. The chatter will not go away. I don't know if it's just valve lash or something else. The car had been down for way to long I've replaced a collapsed lifter checked the push rods. I've searched all over forums and nothing seems to repair my chatter. Please help

 

Is this a new noise? Sounds like a rod knock to me. Perhaps a rod catching the windage tray?

 

About 3 yrs ago I was racing and the engine popped. I lost a lot of power and it limped home. I drover it another couple miles to a shop and at that point it had lost nearly all power. Long story short I did not allow that shop to do any work so I pulled it out and started working on it myself. I've only recently been trying to fix it a lot because the car was stored a long distance away so getting tools and home owner allowing me to come over was rough but now I can work on it every day. (That is still the short story) Anyways I noticed the rocker arm looked different from the rest so I took the intake off and found a collapsed lifter on cylinder #8 intake. I checked the exhaust lifter and it was fine. I checked those two pushrods and they were straight. (In hindsight I see I should have checked all lifters and pushrods.) I replaced the 1 lifter and put everything back together. Before starting it I attempted to adjust valve lash on all 8 cylinders but to be honest it just didn't seem right. I wasn't able to find exact TDC to adjust the cylinders because I have no timing indicator. I did what I thought was right and this is the end result. I thought if I got it to idle then I could just go in and back off the rocker until it chattered and then tighten it until it stopped and set valve lash that way but I don't hear any difference no matter how much I adjust the lash.
That's the whole story, ANY help will be greatly appreciated. I will accept criticism as long as it's constructive.

I'm not sure if there is a wrong way to put the windage tray back on but I will take a second look at that when I remove the intake again.

 

While the motor is starting the compression is not uniform to each cylinder. There is one where the starter speeds up and comes back down. The noise seems to be deeper than a tick, and the shaking of the motor is most likely from at least one or more dead cylinders. I think even a compression test will tell you what's going on. Should do that before anything else.

 

Great info. I was so caught up in the noise I didn't notice the motor was revving just a bit every few seconds. I'll check it out tomorrow and update.

 

I don't mean the engine, but rather the starter motor before the engine fired up. As the starter motor is spinning you can hear it speed up for a brief second. That could mean a cylinder does not have the same compression as the others.

 

OP...

your sound does sound "internal" more than valve train but your lash procedure is not right so you need to deal with that first.

I would do the engine off method starting with #1 cyl at TDC and do 1/2 the valves then rotate engine 1 revolution and do the other 1/2. Go buy a Haynes service book for your car which explains the procedure. You don't need "timing marks" to find TDC. You rotate the engine by hand watching the RR movement. When #1 is TDC you can do both intake and exhaust valves for that cyl. There is a specific order of what intake and what exhaust valve you do when #1 is TDC. Just refer to the service book for the order. Once you do the valves with #1 at TDC you rotate engine by hand one revolution bringing #6 to TDC and do those valves. You do both intake & exhaust on #6 when it is TDC and the various intake & exhaust valves noted in the sequence the book will have.

You find zero lash by screwing in the RR poly lock with your fingers while moving the PR up & down until there is no more up/down movement. It takes a VERY light touch with your fingers in screwing down the poly lock to get to zero lash. Then turn poly 1/2 turn and lock it. Move on to the next valve in the procedure sequence.

You can't tell if your rods are hitting the windage tray by pulling the intake, you need to pull the pan. If you have a 383 and run the stock windage tray you need to stand off the windage tray 1/8" from where it was stock or the rod bolts will hit it. The motor will make a major knock if you don't and you would know this IMMEDIATELY on first start up if that was not done. You just put a 1/8" thick washer on the 3 long main cap studs and also between the tray and oil pump to raise it away from the crank/rods

 

I had a sound that sounded like it was valvetrain related, yeah it was that pistons 1 and 3 were cracked.

 

yeah the sound does seem to be coming from the lower portion of motor but hard to tell on the youtube vid

SSRRR note about the starter changing speeds during crank does suggest the valves are not closing on some cyl which is why I suggest confirming and re-doing the valve lash. This would resolve the issue of valves not closing and that cyl losing compression....but if knock is from below....motor tear down will be needed

Ideally the valve lash will resolve the problem....but from the sound of video there may be deeper issues

 

go purchase a engine stethoscope at your local harbor freight Prime tool store, Maybe it can help you pinpoint where it is coming from, as everyone suggest, I believe its a lower end problem..

 

I know I need to do another valve lash adjustment. I understand how to do it, it just never feels right. That's why I say I think it would be easier if I KNEW the cylinder was at TDC. Anyways I plan on doing that again.

As far as the windage tray I have not pulled the motor since it was built and it has about 10k miles on it. It has always has a slight tick near cylinder #8 but I never found it to be a problem. I raced it hard. It may have been the beginning of this problem but like I said it went a long way that way.

If it's a cracked piston I'm done with this LT

Compression test results are in...

 

Where's the oil? Or does it just not come across in the vid.

 

Well that blows. With hardly any compression in that cylinder, the way it was clattering and shaking, be prepared for the worst.

 

It's the video.

I will pull the motor over sometime in the next few weeks. If I can get away with a rebuild kit I'll do that but if it's anything more I'll just go LS. This motor with nitrous was making 550HP and 416HP on motor so I'm not totally ready to get rid of it but then again I see LS is so much easier to work on.

I appreciate everyone giving me there thoughts. I'll continue to post here once I found out more.