help!!sbc tapping sound

[Fox80]

Yes and no, if the lifters had good rotation in the block the "cup" wouldn't have been very noticeable, the lifter has a higher Rockwell hardness than the cam, and you said you put new lifters on an old cam, so now you lost the wear pattern of the old lifters. Could be many things, a bad "new" lifter, bad cam lobe, lifter sticking in the bore of the block, not enough pre-lash in the lifter, bent pushrod, a valve sticking in the guide, a bad rocker fulcrum, try taking the rocker and pushrod from a quiet cylinder and swapping them, if that doesn't work then you will have to pull the intake and check the lifter, and check the lift on that cam lobe.

 

[pontiacgp]

Have you checked the spark plug?

 

[the82elco]

Yes and no, if the lifters had good rotation in the block the "cup" wouldn't have been very noticeable, the lifter has a higher Rockwell hardness than the cam, and you said you put new lifters on an old cam, so now you lost the wear pattern of the old lifters. Could be many things, a bad "new" lifter, bad cam lobe, lifter sticking in the bore of the block, not enough pre-lash in the lifter, bent pushrod, a valve sticking in the guide, a bad rocker fulcrum, try taking the rocker and pushrod from a quiet cylinder and swapping them, if that doesn't work then you will have to pull the intake and check the lifter, and check the lift on that cam lobe.

i checked the lift by marking the push rod's with a white pen when its open & closed and on the #1 cyl the exhaust opens more than the intake does.. and i checked the next cylinder an they both open & close at the same markings