Okay, the carb issues seem to be solved for the most part. *Might* need to go back in and do a little more work but I'm 100% confident I found the problem and have the solution.
Problem: Carb sticking when it gets good and hot. Won't return to idle, binds up with the throttle open enough to "idle" at around 2000-2200 RPM. You can force the throttle closed but can feel that it's all bound up when you do that and there's a lot of resistance to it re-opening at first.
Hmmm... what could be causing that? It's not the linkage nut, that's plenty loose and there is some play in the adapter even when the problem is happening.
Nope, it's the primary throttle plate. It's just not the right fit in the bore and when it heats up and expands it starts binding in the bore.
Evidence:
Looks like some burrs/jagged edge on the edge of the throttle plate adjacent to the shaft:
Witness mark in the bore where the plate has been rubbing:
Time to remove the throttle plate/butterfly and take a little material off it.
Prepping the patient for surgery (paper towels stuffed into the throttle bore above the butterfly.)
A die grinder makes short work of the staked ends of the retainer screws. gotta be careful not to slip and mar the bore:
A little light filing followed by dressing all the sharp edges with some emery cloth results in clearance, Clarence:
While I had it apart I took off the nasty casting flash all around the bottom of the booster:
There are a lot of things that could be done to this carb that would increase airflow through it. One of these days I'll tackle them, but for now the priority is just getting this truck in reliable running, daily-driver condition.
I put a 195 thermostat in it (had a 180) and drove it around for a half hour, lugging it up hills to get it as hot as I could and the idle pretty much always returns to ~800 RPM which is where it seems happy now. If I start having problems on hot days again I'll just take a tiny bit more off the throttle plate on the other side where it looks like it might be a bit tight. The tiny bit of material I'm removing isn't enough to affect the idle speed.
I gave it a bath and took some pictures with the new shoes, too, so I'll have something to compare to when the new suspension gets installed. I expect the suspension stuff to arrive this week and I'll tackle that task next weekend.
The bed has some rust issues (this is the worst, but there are other spots at most of the seams) but I have a rust-free bed waiting in the wings. Just need to figure out how to prep it properly so this kind of thing doesn't happen again.
The bed had been repainted before I bought the truck but the cab is still original paint which is now faded and starting to peel on the roof. Going to have to deal with that sooner than later as there are patches of surface rust forming on the bare spots on the roof.
I'll probably tackle the interior first though as it needs some work. I'm guessing this truck lived some part of it's life in a much sunnier climate given the overall lack of rust in the cab and frame and the fact the paint is so badly faded and peeling on the cab and all the hard plastic parts in the interior are sun-baked and chalky. I'm guessing the hardest thing to find will be some good door panels. Might have to get these rebuilt.
Dogs like trucks!
Going to drive it to work this week and see how it does. Very timely as my normal daily driver needs brakes bad.
