I had the same problem and it was spun crank bearing. Motor ran fine believe it or not and it finally blew after a complete summer of running it. The temp ran kinda hot a little over 200 °. I would get it checked out.

I think I figured it out. I now have 45-50 psi at 900-1000 rpm idle. And yes, it was something really really stupid. I don't think I can elaborate further. It is just plain embarrassing!!!!

On a motor with clearances set right ,10# per thousand is what gm used to say (bbc) .That being said ,I don't want to idle under 20#'s and the way pumps work , the pressure will rise faster than 10#'s per 1000 throttling up, until you reach the pump blow off pressure. Usually 60 + #'s with the blue spring. Running too much pressure cost power and wears pump / distributor gears faster than necessary.

Shim pump for more pressure, that was advice years ago of Gellner..... hes not new to boat engines... I never wore anything out doing this, ...

You expect to get off that easy around here?? spill it!!

Enquiring minds want to know. You have to tell us. Believe me, no one on here will judge.

You could save a life with your information & think of the children my good man, think of the children!

I have only 15 - 20 psi at idle (750), maybe I have your problem also? Please elaborate, or at least PM.

Come on - spill it !!

Trust me no one has this problem