All, I just completed a rebuild of the 400/4-speed in my 67' Firebird. I had the motor tuned by a professional machine and service shop. I have two issues that I am attempting to source cause: hot start and overheating.
I seem to have a overheat problem both at idle and after driving (at speed). After I start the car and let it idle for 4 to 5 minutes the temp jumps from 180 degrees to 240 degrees (presumably right after the t-stat opens up). I want to source cause the over heating at idle before tacking the over heating when driving as there are likely two different issues here.
I have new high performance water pump, Cold Case aluminum radiator, thermostat, etc. I have yet to IR the radiator inlet and outlet to confirm temperature as displayed on internal aftermarket gauge. I will try the other recommendations I have read (water pump divider plate, thermostat opening, moving timing to 15-18 degrees, checking fuel mixture, checking for air pockets, etc.
Also considering converting to Evans non-water based coolant.
Any other suggestions on source causing the over heating issue?
