I have a '52 F1 with the 239 flathead. It runs well up until about 45MPH then starts choking and sputtering. If I let off the gas it runs fine. Is this normal? It runs at the high end of the water temp range. Could these be related?

 

Probably not, Most flatheads run somewhat hot.

I don’t know much about flatties (or want to) and a professional specialist connoisseur will be along shortly to assist you.

It is common on old fords for the small wire underneath the distributor plate where the points sit to get worn and short out when the vacuum advance pulls on the plate, have a look at it.

This will bump your post to the top. Welcome to the site.

 

THanks.!!!

 

Those sound like classic symptoms of a plugged fuel filter to me. The fuel filter on those things is a strainer screen above the settling bowl on the fuel pump. Have a look at it. If another inline filter has been installed at some point, try replacing that also.

 

If the fuel checks out, next check your point gap and coil output. If you have a week spark it will run badly under load and at high speed.

 

I would put a timing light on it as well, after checking the fuel filter. I’ve see too many times guy’s want to blame a running problem on the carb when its all timing. This is about the time the venturi vacuum comes in. you can check the distributor for movement of the plate with a vacuum pump. The late timing could explain the heating up as well. I would make sue your gauge information is correct. I can run 60mph all day at 180 take it up over 65 and it starts to climb.

 

What is the history of the engine?

Heating sounds about normal for my truck in the summer time. The gauges are woefully inadequate for accuracy.

I agree with the fuel supply for the spluttering - it's the most common cause. Tank clean or new? Lines new? Inline fuel filter in front of the pump?

Too much heat could cause the condenser to fail or even the coil.

 

Thanks everyone. I'll give these things a shot.