Hey all. I am chasing down a small problem with the engine. Truck is my 3/4 ton 49 w 216, W1 car. Running r45 ac plugs, stock exhaust system.
Truck has at least 75,000 miles on this engine.
On the trip to yellowstone a few months back the truck developed a slight stumble off idle. I learned how to work with it, because I could not find anything wrong, valves were in check, carb settings were all there, timing was spot on and If I adjusted it made no difference. same with the carb.
So yesterday I am at the barn(about 30min from the house) and I go to fire up the truck.
It fires, but then dies shortly after starting. It would run with the choke out slightly. So I was thinking vacuum leak. I sprayed a little carb cleaner around the plugs, the advance line fittings(both ends) andthe manifold(both ends-to engine, and to carb) as well as the vacuum port for the wipers. No noticeable change.
So When I got stranded on the way home I had the mrs bring the spare carb. That got the engine running somewhat better, at least it would not die at idle, and I was able to make it home. It would blow a little blue smoke while driving.
So today I began to seriously troubleshoot.
Checked the plugs and wires. All show spark(by hooking wire to plug against block, and by hooking timing light pickup to wire to use impulse to signal the light).
I then tore both carbs down side by side.
I found some parts on the carb that was on the truck to be suspect.
Using the two I built one carb out of the best parts.
Putting that carb back on the truck now idles well after starting, accelerates smoothly through the rpm range. The vacuum gauge connected to the wiper port does read a little over 20, drops when accelerating then normalizes to 20+/- once I am more steady on the accelerator.
After idling for a few mintues a stumble occurs. Changing the idle adjustment(both mixture and speed) does not change this.
So after all that I am wondering if maybe I have a valve sticking open?(perhaps exhaust?)
I do get a little blue smoke (very faint) during the stumbling.
Thanks for your input, I look forward to reading your responses.
