[Tripower455]

Well, I did the plate mod on my hot running 455...... A small change, but it still gets up to 230+ after idling for about 20 minutes.

I hammered the plate until it just touched the impeller without a gasket. It was perfect and doesn't bind at all with a gasket in there.

The setup is:

'66 GTO
.030 over 455
'66 Tripower (#69s in the center and #73s in the secondaries)
Manual trans.
Cast impeller iron water pump
Rodney Red (non AC, 15") drop in radiator
HD fan clutch
March underdrive pulley
repro '66 A/C shroud
160 degree stat (I'm gonna try the drill mod next and make sure it's a high flow)

Crane hydraulic roller HR-222/339 (part number 289621)
Daves Small Body HEI with vac advance disconnected (I'm gonna try manifold vac and see if it runs cooler at idle)

I am using an Autometer temp gauge, and have double checked that it's accurate with a meat thermometer in the radiator. Plus, it is filling my catch can.....

Everything is brand new, and the car has about 500 miles on it since complete ground up, every nut and bolt restification.

If the car is moving, it runs at about 185 or so, and doesn't start rising until I sit in traffic or stop. Before the plate mod, it would creep up to about 210 with the air off, but would come down pretty quickly once I got moving again, and would even out at about 185 while moving. The idle is set at 850, and it is pulling 16" of vacuum at idle. The fan blows like a Cessna when it heats up. It is moving a lot of air. The water flow through the radiator is 100% better than before tightening up the plate/impeller clearance.

The idle mixture was a bit lean, as I had a little hesitation in off idle acceleration, but I've got that just about perfect turning the screws out a bit.

I am hoping that I don't need more radiator. I am going to try baffling the shroud better.......