Thread: The problem: overheating at idle in drive – stalling when hot.

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Lots of information right up front.
Well done there.

I'm with Eric on the fuel pressure, try a regulator.
Holley makes a nice one that's not too costly.

Time the engine with a timing light.
You'll probably find the timing off a bit.
The timing light will also tell you if the mechanical and vacuum advance are working.
Retarded timing at idle is a big cause of overheating.

One small hint about the two 1/8" holes drilled in the thermostat flange - one is sufficient for an air lock relief.
Two will bypass too much coolant for a reasonably quick warmup.

In 16 degree F weather my 32 roadster with 462" Buick engine running two 1/8" holes in the 180 themostat takes 4-5 miles of 35-40 mph cruising to hit warm on the water temp gauge and you can tell the oil is not sufficiently warm at that time.
Running another of the same brand 180 degree thermostats with only one 1/8" hole drilled, the water temp hit's 180 in one mile on the same road - also during 16 degree weather - and the engine oil temp is warmer at the end of the 4-5 miles . . . to the donut shop.


Your overheating is very much like the Ford 400-M (Cleveland tall deck block) engine in my 77 Ford 3/4 ton 4x4 did.
Ran a few degrees warm on the highway in summer, but well within limits.
About 190 degrees vs 180 with a 180 degree Chevy thermostat.

It overheated in traffic to the point where you'd be looking for an escape route after 5-10 minutes - depending on the ambient temp.

Problem was:
At the time Ford and the other thermostat manufacturers made only one thermostat for the 400-M engine.
197 degrees rated.
I wanted a 180 degree thermostat and found a Chevy pattern thermostat dropped right in.

I didn't realize at the time that Ford stats have a plug on the bottom of the stat that closes off the bypass hole in the bottom of the thermostat well when the stat is open.
That allowed a little less than half the coolant to circulate in the block instead of having all the coolant go through the radiator.

The problem can be cured by either installing the correct pattern Ford thermostat or . . . tap the hole at the bottom of the thermostat well and install a flush head allen driven pipe plug.
1/4-NPT if I remember right.
That allows a Chevy pattern stat to be installed and all coolant then goes through the radiator.
Warmup does take longer, but at the time I lived in SoCal so no big deal.

Take a look at your FE engine's thermostat well and see if there's a 3/8" or so hole at the bottom of it.

Only took me one re-cored with a Desert core radiator, one water pump, trips to two radiator shops that couldn't figure it out along with a few worrisome miles before I realized what I'd done.

Sometimes we shoot ourselves in the foot and don't even know it....

It isn't the gaskets in backwards. You won't get out of sight of home if that's the problem.
I had a 390 that acted much the same as yours. My problem was the lifters would collapse at idle for any length of time. Aftermarket crappy lifters. Put new Ford lifters in, ran perfect.
I wish I had your problem, as long as the 'Bird went with it!!!