lifter tap after cam install.......need help

[kyhunter89]

im interested to know the answer to this...

[classic1]

The LS motors seem to have a tapping noise with aftermarket cams due to the fast ramp rates of the cam. I've heard people say they have the sewing machine type noise to them after a cam install. It seems to be normal.

Hopefully someone will chime in that can give you a better answer but that's what I have heard.

[molitor]

I installed a GM p/n 12561721 camshaft in my 4.8L a while bad to replace the factory camshaft. The original one ended up chewing a lifter and a lobe all to pieces. That being said, after installing it, the valve train was making plenty of noise. Unfortunately, i later found that the company that did the valve job on my cylinder heads did not grind the valve stems back down after cutting the seats which resulted in a greater installed height at the rocker tip. and this turned into a higher preload on my lifters. And it was tapping...a lot. So i went with shorter pushrods. That pretty much took care of the problem. I did replace all of the lifters though.

I can tell you that with 150k miles, those lifters probably have a whole lot of wear in them and they are probably full of carbon deposits from old oil. And therefore they are probably sticking. If that werent bad enough, the base circle on that cam shaft may be different from the stock profile which will make all sorts of noise of clearance issues. You can have too much or not enough.

I don't know the problem, but i'm offering what i have found that can cause this. At any rate. you ought to check the tip clearance on the rockers by rolling the engine around until each set of valves is completely closed and make sure each rocker tip will slide side to side on the valve tip. If you get one that doesn't move, you don't have enough clearance.

[Duct_tape123]

Did you center the oil pump correctly? Could be low pressure, or inadequate flow.

[ssanderson]

so i ran some bg engine cleaner through the motor tonight and i changed my oil and it still does the same thing. the thing thats confusing is it starts fine but after u drive it for a few miles it starts then after a few more miles it quits, but the engine runs fine when it does make the tapping noise, and my oil pressure is still good, 45psi at idle and 60psi crusin, i also run synthetic oil.

i just dont know what to do, i guess im going to be workin on it this weekend

[ssanderson]

so i went ahead with what molitor said a put new ls6 lifters in it and everything was goin good she wasent tapping anymore and the motor was even quieter but this past friday it started again and it did it yesterday too.

anymore thoughts on that?

[GraniteBlueNNBS]

Live with it bro. its pretty normal on a LS engine with a big cam.