Truck info: 1985 newer block is rebuilt. bought as a parts truck.

Engine starts and runs perfect till it gets to operating temp then it idles down and dies. Almost like something is getting tight. will crank over but very slowly.

Ive swapped carbs and intakes. my only thought was maybe who ever did the machine work did it to tight? as everything expands it gets a little friction and pulls the motor down enough to kill it?

 

What are your high and low idle speeds? What valve adjustment specs did you use?

 

When hot, pull the plugs and try turning the engine by hand. See if it truly is tight.
is there still spark after it stalls?
is the temp sensor measuring correctly when hot? I've had one fail that was still within the range of possibilities but would lead the ECU to
think it was about -20*F outside when it was around 65* causing the car to stall.

 

What is the oil pressure ??

Who assembled the engine they should have checked the clearance !!

New Fuel filter ??

 

Has spark, oil pressure and air cleaner removed. Not sure who resembled the engine. Ill check valve clearance. Didnt even think about that.

 

This is an issue i have had in the past (feeling a lot more resistance than i recall from previous times turning the engine by hand) and am now facing a somewhat similar idling issue to what the original post described and so I am wondering how those two may be correlated? what could be too tight that would cause this? valves too tight certainly would make it feel like you're fighting something, but could overly tight valves really kill the engine? wouldn't you bend a valve if they were that tight?