347 oil pressure question and surging

[silver_pilate]

I've recently finished building the new 347 for my '91 GT. It's been running for several months now, but not on the street until I get these issues resolved.

When we first started it up, it ran fine, good pressures, though a little warm. Took it to Lubbock, and noticed that as it warmed up, the oil pressure dropped significantly on the stock guage. When it idled, the pressure guage dropped all the way to nothing, and the car surged and died. When you rev the motor above 1000 rpms, the pressure comes back up. Another thing I noticed is a significant amount of blue smoke (burning oil) after I accelerate moderately or hard, especially when I lift off.

Anyway, so I installed a new electronic oil pressure guage so I could watch the actual numbers. When you start it up, pressure runs around 45-50 psi. As it warms, pressure slowly drops, and when it reaches normal operating temps, pressure at idle reads around 12. I'm not too worried about this, as I'm fairly sure the guys doing the machine work on the short block milled it to fairly loose tolerances, and when you bring the rpm's up, pressure immediatley responds by jumping back to near 40 psi. Does this sound fairly normal?

At the same time, once the motor gets to operating temp, the car surges badly anywhere below 1000 rpm, and eventually will surge itself to a stall. The oil pressure still reads around 12 psi (surging with the idle), so I know I'm getting oil to the bearings. I think this is related to bad valve seals. When we tore the motor down, we degreased the heads and cleaned 'em up while they were still assembled. They sat without a motor for about two weeks, and I'm sure the seals were probably ruined by the combo of degreaser and no oil (I know, not the smartest thing). So, my theory is that once the oil warms up and becomes less viscous and the valve seals expand, oil is able to run down the valve stems into the combustion chamber and is quenching the ignition process. Does this make sense to anyone else? Sound like a likely cause of surging?

We'll be replacing the seals shortly, but I just wanted any other ideas as to the cause.

Thanks!

Oh yeah, we also took my radiator to the shop and had it hot tanked and rotted. It did help keep operating temps more normal.

--nathan