Thought I would do a tune-up on the 1952 3100 that I purchased a few months ago.
The engine is a 1961 235 connected to a 4 speed trans. and was running pretty good but wasn’t sure of the age of the parts so thought I would replace them and start “fresh”.
Took the truck to a mechanic I’ve known for over 40 years and is familiar with the old GM 6 cylinder engines. He changed the plugs (R45 at .035" gap) and replaced the points (set at 0.19"), condenser, rotor and cap. He set the timing so the pointer lined up with the “U/C” mark on the flywheel. The engine was idling smooth after he finished so I headed home. I didn’t get far when I noticed the engine was surging and there was a dead spot where the engine speed didn’t increase when I pushed the accelerator. Once I got into 4th gear, it took about 3/4 mile to get up to 55 mph. Since it was closing time, I waited the next day to take the truck back to him. He just checked the work he had done the day before and everything looked okay. I told him that since it was surging, I suspected a fuel problem so I changed the glass bowl filter and also the one next to the fuel tank outlet. The previous owner had cut out a section of the hard fuel line and installed an inline filter.
Although it looked clear (a plastic see-through filter), I replaced it with a new one from NAPA. While I had the filter off, I opened up the shut off valve under the tank and there was a good flow of gas out of the tank so I was sure that the outlet hadn’t been clogged with debris from inside the tank.
After he finished checking everything, I took it for a test drive and found it was still surging. I asked him to drive it also and he agreed there was a problem.
He said that sometimes this could be from bad points so he removed the new ones and put in another set. The engine ran smoother but after another test drive, he said it was still surging. Since he was in the middle of another job when I showed up, he asked me to bring it back next week.
He is going to pull the top off the Carter YF carb and see if there is anything there that could be causing the problem. I told him I would post on Stovebolt.com and see if I could get some help from the members.
Would appreciate any help/information you can provide.
