I guess I'm going have to eat some humble pie. It looks like the problem
was not an exhaust system restriction.

After I put the flowmaster on the truck and drove it around I took out the
plugs and the insulators were pinkish in color. Hmm, looks like the carb is
running lean. So, I took my truck to a shop that specializes in carb work
and asked them to check the air-fuel mixture. Well they did and they said
the carb was running slightly rich. However, the real problem was that the
timing was off and that is why the engine was overheating. The previous
mechanic swears up and down that he set the timing correctly.

I have not yet tested the truck for overheating because a seal on the
steering box started leaking like crazy and its back in the shop for
steering box repairs.

Go figure, while I had the engine out for rebuilding I did not overhaul the
power steering box (although I did put in a rebuilt power steering pump and
hoses) because the previous owner had overhauled it three years ago. The
truck had been immobile for the 18 months prior its resurrection and I guess
the seal did not like being brought back to life.

As soon as I get the truck back I will post an update on my journey of truck
rebuilding.

-David

"Steve Barker" <railphotonut (AT) not (DOT) hotmail.com> wrote

My '75 F150 with 360 2100 motorcraft carb warner 4 speed and AC/PS
was getting too hot too...

I had a leak in my vacuum advance motor, replaced.
Installed a -new- water pump and cap checked for good seal there.
Replaced my leaky after market (added it myself) clutch fan clutch.
Experimented with some main jet changes went back to what I had.

My over heating went away right after I did the next thing tho...
Went from a three core to a four core radiator that was about $307.

The old radiator was in good shape but dirty (only on the outside)
from weeping, of course any leaks, even slight, have a real negative
effect.

If I had an automatic I would consider an extra raditor for it
instead of adding that heat to my engine. But don't know nuthing
about it really. :/

Anyway... my setup never held the amount of water and coolant that
the service manual sez it should... until I replaced the original
designed radiator with that new four core...now it's right on the
money- what they said it should be. Ford shorted me on a simple
radiator, no kidding. :/

Here lately it's running even cooler after I cut into the exhaust Y
pipe and found it really crappy looking in there. It looked like a
football shaped torch cut hole with lots of slag hanging from it and
the hole was no bigger than a golf ball! Ford shorted me there
too. Hey, it has more power now that -both- sides of the engine are
running.

Alvin in AZ