I finally got the engine put back into my daughter's '74 Valiant and for the first few days, it seemed to run okay after I did a rough setup and tune on the carb. But yesterday is started to stall randomly. I'd take it for a spin around the neighborhood and it would want to stall at certain points: going over a speed bump, slowing down for a corner, slowing/stopping for a stop sign. I tried increasing the curb idle in 100RPM increments up to 1000RPM, but no change. I changed the fuel filter, as I could see sediment collecting in the media (clear plastic case, with Dan's fuel line mod). This was the first tank since the engine rebuild and >15 years of sitting in a field although I added 10 gallon of fresh fuel and some fuel stabilizer. When I did the filter change, I got a face full of fuel for the effort, so it appears that the carb was seeing pressure. Timing is at 5' advanced at 750RPM, but this took several days of effort because the dizzy seemed to max out at 0' of initial timing and I couldn't fine another tooth in the gear that would let me adjust it further. I ended up moving the plug wires over 1 spot (so 60' advanced) and then moved the dizzy to a new tooth on the gear. That gave me about 5' advanced right in the middle of the dizzy adjustment range. At that point I went into the drivers seat, which rocked the car (it was idling in my driveway), and the engine wanted to stall. Hmmmm. I gave the car a hefty wiggle and it tried to stall again. Repeat the motion and the stall shows up. I suspect that I may have a fuel pressure (too much) or a high float in the carb. Any other thoughts?
Tomorrow:
- Test fuel pressure. Google tells me that too much pressure can override the needle/seat/float. A regulator should fix this if this is the issue.
- Check carb float level. Might as well clean the carb while I'm at it, although I just rebuilt it last week before the engine was fired up for the first time in forever.
- Check needle and seat. Maybe a piece of debris got past the filter and is holding open the needle valve?
Note that the carb was rebuilt about a week ago. So was the engine (new rings, bearings, new cam (818i/819e), cam timing set at about 103'). After break-in and several days of driveway tuning, the engine compression is 150PSI across all cylinders. Plugs look black with a slight amount of tan on the tips of the electrodes (likely rich). I've also adjusted the mixture screw using a vacuum gauge, which peaked at about 15 inches. It feels like this screw is too far in. During drives, it feels a bit sluggish. Granted, this is a 50-year-old vehicle, and I don't have any reference point besides my modern cars. I also had a problem with the trans, but adjusting the kickdown linkage (several times), plus an ATF change (including draining the torque converter) fixed that issue.