USAsOnlyWay

Hey guys, a friend of mine here just picked up an LT1 he wants me to go over some things he isn't familiar with. Tell me what you think, I have my opinions but I'd like a second, maybe he will log on here later.

Anyway thanks, this is what he wrote:

???

SupaVette

Maybe too much piston clearance?

USAsOnlyWay

As in the piston is rocking?

SupaVette

Yeah, i was thinking along the lines that maybe the bores are worn and the pistons are rattling till they warm up. But it's just a thought

USAsOnlyWay

Hey, keep em coming!

I'll just hope for him thats not the case, I wanna say it has like 72k miles and is stock.

What about the oil pump being worn or perhaps it being low on oil so it takes a long time to oil all the rockers???

Nathan Plemons

I wouldn't think it would be the oil pump if it's showing good oil pressure, something to check. Take a screwdriver and put it on the valve cover while it's running and put your ear to the other end. Move it along the length of the valve cover and see if it gets louder in any one spot. It should sound like a sewing machine, if you hear any clicking you've got a loose rocker.

SupaVette

Hmm could be, but even if it took long to get oil up, i would never imagine it would take the time it takes for the enginge to warm up. Maybe the rockers are out of adjustment, and arn't compressing the lifters (just sitting on the edge of the lifters travel)

Nathan Plemons

And as it warms up the thermal expansion takes out the slack.

USAsOnlyWay

Ok, I am with you guys and I can definitly see that happening on a 72k motor. I'll pass it on and maybe I will see the car for myself this weekend sometime.

93 ragtop

Just for your information, pretty much everything is the same on the LT1 vs L98 (that could cause this type of noise) . The intake is different and the distriutor. I would be surprised if it was piston slap, exspecially at that rpm. The Lt1 cylinders and pistons actually wear very well which is probably due to the use of synthetic oil. Good luck and let us know what you find.

bogus

I think the LT1 had off and on problems with piston slap.

Nathan Plemons

First I've ever heard of it. I know the LS1's had ring issues.

USAsOnlyWay

Yeah, I hadn't heard of that either bogus. But that is the reason why I asked LT1 guys in specific. I don't know what problems may be widely known that I overlooked as it didn't apply directly to me.

Can anybody else confirm this piston slap myth?

(Right now I would put money on rockers though)

ittlfly

I would think that if it were loose rockers it would clatter from off idle all the way up. It sounds somewhat like piston slap to me also. Especially since the noise disappers when warm....however, like rockers, you should hear it off idle when cold too. Ask me how I know.