Arborvitian, Keep us posted on getting you truck running good with that Jet Qjet. Hope you get it running good
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So far, no improvement. I took the truck to work the other day. I fired it up, and it idled like it had a big cam in it. Blat blat blat shudder stumble. It never did that before. Got it fired up and ignored the fast idle. Drove it to work. I figured by the time I got to work, that stuff would have sorted itself out, but no dice. At the stop sign after a long highway cruise, it was idling stupid high. On the return trip, I had more time to baby it, and I managed to blip the throttle hard enough and often enough to finally kick it down to behaving sensibly.
Could the choke be getting stuck partly closed? It feels like it's stuck on the fast idle, but the butterfly seems to be wide open every time I look. Maybe it's 10% closed or something.
It made the trip, which is in the win column for a 50 year old truck with an original motor, but it burned way too much gas, and I was nervous the whole time. It needs more work.
The tach goes flaky around 3,000 RPM under load, and I don't think it's a signaling problem. It could be a fuel delivery problem or an ignition problem. I know my total mechanical advance at 3000 RPM is only 26° with a base timing of 12°, so I'm going with the theory that I have ignition problems. I have a new Pertronix distributor to bolt on whenever I get a day when the weather doesn't suck.
After that, I guess I'm going to get out Cliff's book and start going through my shiny Stage 1 to figure out what's wrong with it. This will probably still be faster than rebuilding my original carburetor, but believe me, I've got that thing in a safe place. If a bucket of carb dunk didn't cost $55, I would have already dunked it in preparation to see if I am better at rebuilding carburetors at the age of 52 than I was when I was 18. Considering how badly the last carb I rebuilt ran, I'm reluctant to drop $55 on a bucket of solvent, but I am more patient now, and even have a hobby machine shop.
My Qjet acted similarly. The power valve was stuck open. Don't know why. Don't recall of any backfires or similar events, but it was stuck. If yours was set too high or wrongly jetted, might expect similar results
Power valve. That ended up being kind of a rabbit hole for my thought process. Could something just be getting stuck?
I had a lot of trash in the gas tank initially, and ended up clogging the fuel filter very quickly. The last filter I took apart was full of an impressive amount of rust, so I installed a new gas tank at that point. What if some trash made it into the carburettor?
It's worth pulling it off and going through it to have a look. I think I'll wait and see what happens with the new ignition first though. I feel like I probably do have a real ignition problem. Not enough mechanical advance seems like a definite, and the inside of the distributor is seriously rusty and crappy looking. Hotter spark won't hurt anything, and my points are going out of adjustment within 200 miles, so something in there just ain't right. I'll swap all that, then start over setting the timing and idle, and then see what's going on after that.
If I get a day to work on it before spring. No heated garage for this ice tree mechanic.