strange off-idle clattering sound in my 350

[Taibo]

Originally Posted by mattfranklin

Most were about zero lash except for #5, which had one about two turns in. It seems to idle better now, BUT the off-idle noise is still there.

What's left? Rod bearings, fuel pump push rod, exhaust leaks? Motor mounts? Clutch/flywheel innards? Harmonic balancer?

All of the suggestions so far are good, but much less likely than a simple exhaust leak between manifold and cylinder head. Before worring about rod bearings and fuel pump pushrods, check for a leak. You can sometimes find them if there's soot on the manifold but if your engine is covered with crud looking for black soot on black burned oil and grease isn't going to help you.

[mattfranklin]

THE VERDICT: It looks like they used STANDARD rod bearings on a 0.010 under crank. I confess I'm kind of a hack mechanic myself, but even I know that is just plain wrong. See build thread for details.

[hamjet]

Wow! I'm shocked you had any oil pressure at all! Thats why I always double check with plastigauge. Good for you finding it..