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:

1. 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.
2. 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.
3. 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.

I would suspect something electrical.

Check and clean all of the firewall bulkhead connections.

Good luck!

Greg

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before checking float ,fuel level read this https://www.slantsix.org/forum/viewtopi ... 19&t=66220 and have new kit with accelerator pump cup, might be able to get spare pump with out buying whole kit Get very fine sand paper,polish pump bore. so cup wont tear up smooth surface. if using used pump cup put in freezer to shrink it. New float might be good idea. short answer for now

On hot engine shut off, remove top and look at fuel level, measure from top of bowl, should not be near top. heavy float, dirty needle and seat etc, adjust as needed.

The gasket interface inside the throat is moist. I dried it with some carb cleaner, restarted the engine, and the dampness came back. I also see some drips of fuel from the Venturi area when the engine is off. Fuel pressure after the filter is above 7 psig. I pulled off the top of the carb and the fuel level is below the body top by about 0.175” in the rear and 0.5975” in the front (my driveway is sloped). I used a digital caliper to measure the depth of the fuel level.
I think that the fuel level is likely set at a hood level but my gasket is bad and the fuel pressure is pushing past the gasket.

Since I had pulled the accelerator pump cup out of its home when I looked at the body and fuel level, I decided to pull the whole carb off and clean it. The fuel was cloudy and brownish, so the filter is letting small particles through. Any suggestions for a fine filter?

I also found that the power valve was stuck about 1/2 down. I removed it, cleaned it, and reinstalled it. I’m not sure how it got hung up.

I lowered the float level to be a hair under the body. It was found to be about 1/32 or 2/32 past the body.

I also found that the screw locations for the top/bowl had helicoils installed, which is fine, but the little tangs had not been knocked out, which may have been a reason that the screws could not clamp down enough. I knocked them out in any case.

After reinstalling the carb, I don’t see any more moisture inside the throat, but the engine still stalls when I rock the car. I rechecked the mixture screw, maximizing the vacuum at idle.

first thought fuel pressure spec for slant is 3 1/2 - 5 psi, so thats way over , so results in high fuel level

I bought a Mr Gasket fuel pressure regulator and it seems to have fixed the issue. I set it to 5psi and the issue got better but still would stall at times. I dropped it to 2psi and it hasn’t stalled yet. I’ll take it on a few drives this weekend to confirm.

There's a second bolt holding the distributor hold-down plate to the underside of the distributor. If you run out of adjustment range before you reach the desired setting, you loosen that second bolt, move the hold-down plate, tighten the bolt, reinstall the distributor, and keep the plug wires where they're meant to be. Go put this right or you will cause yourself and/or others a whole lot of trouble, strife, and wasted time and effort in the future.

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Too many people who were born on third base actually believe they've hit a triple.

Will do, Dan. Just when I thought I had cobbled together a band-aid solution, you have to chime in with your logic and wisdom.

Why would you want to miss out on all that fun!!

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12.70 @ 104.6

Well I definitely have a problem with the float, needle, and/or seat. My daughter took the car for a ride and broke down shortly after. It wouldn’t catch when we tried to start it and further inspection of the carb throat showed fuel pouring into the manifold below. I dropped the regulator pressure down to 1psi, removed and reinstalled the needle and seat, and she fired up. I’ll order a new float and valve assembly. The float is original but the valve assembly is new.

Is spring 39 float shaft retainer pushing down on 23 float hinge shaft. Top bowl screws had heli-coil, float might be shifting around a little.

The float might be hanging up on side wall of bowl, might need to bend arm

https://www.oreillyauto.com/detail/c/wa ... wlk0/10048 Brass float from walker might have better float buoyancy than plastic float. See what Dan thinks.