76 Duster Overheating at idle

[AJ/FormS]

Car also doesn’t like to start if I go into a store for like 20 minutes

A) Does it crank at normal speed? or
B) Does it crank much slower than normal?
If B;
Ten to 20 minutes is just the right amount of time for the engine to heat up from "heat soak". It is possible that your pistons are swelling up and jaming in the bores; OR more likely, the rings are swelling up, the gaps butting, and they are jamming up the works.
Wait another 20/30 minutes with the hood open, and try again. If it fires right up, there you go, the engine will have to come out and the ring-gaps opened up.
Yes this happened to me.
After I solved this, I had no more heating issues, and in fact, I could now run her at 207*F , on purpose. AND Good news!, Fuel-consumption decreased.

 

[Mike69cuda]

Do you know the application of the pulleys you're using? Are they single groove?

Mine is an ac car, so the pulleys are different. Also, mine is a Frankenstein car, so no telling where it all came from. I think the 5.75 (or close to that)water pump pulleys are fairly common. If you take some pictures of yours with a tape measure on the depth & post a wanted ad on here, you will probably find one.

I can’t really tell from the pictures, but it looks like you are running an aluminum (70 - up) water pump - bottom outlet on the passenger side. That makes a difference, as the water pump snout is longer.

 

[Bewy]

RRR.
Thanks for the nice words, appreciated. Geoff.