Hello all, longtime lurker, first time poster. I humbly post to Stovebolt where I hope someone can help me out. I have taken my truck to two mechanic shops which have failed to fix the problem permanently.
About the truck: 1950 Chevy 3100. It had sat for 20 years outside, been stolen once, and restored sometime in the 70's or 80's. Based on the valve cover, and the serial number stampings on the side of the block and head, I believe I have a late model 235, sometime between 58-62 is my best guess.
About me: Aircraft mechanic for the Air National Guard, but not a vehicle mechanic per se, unless you count the Youtube Academy and forum lurking. I've tried to do as much as I can on my own to learn and save some $$$.
Here we go:
I bought the truck sitting in a storage yard where it had been sitting for at least eight years. It had the aforementioned inline six, with a stock single barrel carb and a newer, unidentified alternator on it, and had what we thought was a Buick ignition coil (going of serial #'s) on it. After getting it on tires to get it rolling, myself, with the help of others did the following: brand new fuel tank, purged fuel lines, new points, new condenser, new plugs, new wires, new rotor cap, and oil change. At this time we attempted to start the vehicle, it was turning freely, and after finally getting everything in the right place, it fired up. It ran like a top, the best way to describe it was it sounded like a sewing machine--quiet, low RPMS, very smooth and pleasant sounding. After some brake work, we drove it around town and it ran very nice. After a little more work on the brakes (front disc conversion) I took it to a mechanic in town to have them bleed the brakes better than I, and look everything over for safety's sake. I picked it up on a Friday afternoon the weekend I was moving out of state. Almost immediately I noticed it was running extremely rough and would only run if it was taking on a lot of fuel, and even then it sounded terrible. Instead of leaving it behind for the mechanic to go over again, I took it with on the move. I called the shop up, told them the issue, and they said they hadn't messed with any throttle settings but recommended I check the accelerator pump in the carb. I then rebuilt the carb with a Mike's Carburetor kit and instructions and still had the same issue--real rough running, not holding idle, only running with a ton of fuel. Around this time I upgraded the unknown alternator with one from a '79 Chevy pickup.
Now in Denver, I tried to think of what could be causing it. I replaced the Rochester single barrel with a Weber 32/36 from Langdon's. (I briefly tried to explain the issue to Tom, but the more I talked the more flummoxed he got) Still having the issue after the new carb, I put on a new fuel pump that had the recommended flow, per Weber/Landon's specs. I checked vacuum advance, looked for vacuum leaks, valves not opening or closing. Nothing appeared off. I then took it to a mechanic here in Denver. After a few days they called back and said the truck was ready. I went in and they said they checked compression and timing, both were good. There was a loose bolt here and there, but nothing funky. They changed contacts, coil, and spark plugs. We went out to the shop and it was running just like it had when we brought it back to life--like a sewing machine, nice and quiet, and very healthy sounding. I asked if that was really all it took, swapping coil, plugs, and contacts and they said yes. I didn't understand but thought maybe I overlooked something.
I was ecstatic regardless, I drove it around all night, then the next day we took it to lunch in Morrison (20 minutes from where I live). It made it to lunch fine, still running smoothly, but on the drive back it started feeling funny again. By the time we had made it home, and since then, it has gone back to rough running. Will not hold idle without gas, and generally doesnt sound right. (Still dealing with that shop on a refund or a "fix") I pulled the spark plugs and they were covered in black soot already. I cleaned what I could off the spark plugs thinking if I got them clean again it should run like a top again. Unfortunately, it still ran poorly. Not holding idle, not running like a sewing machine. I tried messing with idle speed on the Weber, but it really did nothing different.
So, as the title says, I guess I'm back to plugs and the distributor; perhaps the coil as well. Could it be I'm frying spark plugs somehow? Is the distributor not functioning properly? Is the coil too hot? Is the condenser incorrect? Is the alternator incompatible? Do I just have the wrong darn spark plugs? At this point I'm thinking about swapping over to HEI or something to eliminate one more thing, but I don't want to continue throwing parts at it (even if that would be an upgrade).
Would appreciate any help or suggestions you fine folks have. At this point I don't know what to do otherwise.
Many thanks,
Jared in Denver
