Hi everyone, just found this forum and hoping you can help.  I have a tapping noise that I can't pin down and it's driving me crazy.

Motor specs:

1970-something 350, rebuilt .060" over
stock crank and rods, I think the crank was ground .020"
9.5:1 compression
new aluminum heads
crane hydraulic flat cam and lifters, 210/216, 440/454, 114 LDA
msd distro and 6A box
1 5/8" headers
21" vacuum @ 1000 rpm

The motor has about 250 miles on it since the rebuild.  Oil pressure goes between 20-55 psi with 10w30 conventional oil.  I've set and reset the lifters a few times, most recently when I added the heads.  There is absolutely no lifter noise present.

My problem is that it still sounds like a lifter is tapping.  I know it's not an exhaust leak - I've chased down a number of those and I can tell the difference.  What's strange is that it sounds louder if I get down under the front of the car and listen.  I don't know what a bad bearing sounds like - could I be confusing that for a lifter?  Is it possible that the fuel pump pushrod is making noise?  It's a new ARP rod but I swear that's where the noise is coming from.

It is a very regular sound at idle (tap...tap...tap...tap), which gets really loud right off idle (TAPTAPTAPTAP) and then goes away (or gets drowned out, I'm not sure) at crusing rpm.  I've changed cams, lifters, and heads since the short block was rebuilt and yet this noise remains.  Overall the motor runs very strong, although I haven't taken it above 4000 rpm yet (paranoid about break-in).  No leaks or smoke or anything.  Plugs are burning perfectly.

Any info/ideas/suggestions you can provide are appreciated.  I am afraid that this is linked to a lousy rebuild but I guess I just need someone to confirm that.  Hopefully it's something simple (and cheaper).

Thanks,

Eric  

Hey Eric,,,first things first. To make sure its a fuel pump rod instead of a lifter or unadjusted rocker, take a long 3/8 drive extention, start the motor and find a place where you can safely place one end of the extention on the pump and the other end to your ear...if thats what it is no other noise will drown it out, it will be as clear as day.  

Look a crack in your fly wheel.I just went through the same thing.  

Eric,  This query is old and the other guys have a great inputs for you.

But, I saw the same thing last year and the issue was the pushrod for the fuel pump BECAUSE during the rebuild, the THICK Mr. Gasket fuel pump block plate and pump gaskets were so thick that the recoil for the pump spring created a ticking...trying to keep up with engine rpm. Thinner gaskets-no more noise.

I hope that this helps-

Roc