engine and drivetrain Weird Stumbling Problem

[amdavidson]

My 75 has a weird stumbling problem while maintaining an even speed.

It starts fine both when hot and after sitting for a few days. She also does fine when you're accelerating hard like when getting on the freeway. She also idles fairly well, but when you're loping along at 2-3k maintaining an even throttle she stutters and stumbles.

New plug wires, distributor cap and rotor, and new fuel filter hasn't helped.

I'm definitely no expert on carbureted engines yet, so a hint as to where to look next would be great.

Thanks in advance.

[smithdog57]

I had the same issue, it turned out to be oil on the clutch disk form a leaking main seal. The leak was small enough that there were no drips but over time the disk was very sticky.

[TobyB]

That usually happens to me after 4 or 5 drinks...

have you noticed that it wanders a bit, too?

Is this a new problem? If so, check the float level. ANd the float.

That'll show up most at cruise...

If it's an old problem and the fuel level's right, then it's time to

look at the transition (idle) and main jets. Usually on a 32, it'll

be on the main at cruise, so it's pretty easy.

Start there and see what you find...

t

[amdavidson]

Thanks, this is a new issue to me as I just bought the car.

The P/O says that it didn't happen to him, but who knows.

I'll take a swing at checking the float levels and jets when I get home.

[Mike87]

If it has a weber 32/36 or 38/38, check to make sure that the auxiliary venturis are tight. They work loose over time and will 'leak' fuel. You can tighten them by peening the ends or adding a shim to keep them tight.

[amdavidson]

If it has a weber 32/36 or 38/38, check to make sure that the auxiliary venturis are tight. They work loose over time and will 'leak' fuel. You can tighten them by peening the ends or adding a shim to keep them tight.

It has the stock carburetor, but that's good to keep in mind.

[Jaycen_PNW2002]

New points too or do you run a Pertronix? Did you check the timing too? Adjust the valves? It always good to check all the variables within one system before tackling another system (fuel).

[amdavidson]

New points too or do you run a Pertronix? Did you check the timing too? Adjust the valves? It always good to check all the variables within one system before tackling another system (fuel).

Still running points, haven't replaced them myself and don't know how old they are. I'll check that.

Timing is on my list for tonight, need to pick up a timing light on the way home. Dwell read ~65 degrees last night. I read online that it should be 60, but didn't find an allowable range. Is that close enough?

Haven't looked at the valves yet, but the valve cover gasket weeps a little and I have a new one, so I'll tackle that this weekend.

[Skippy_the_Bush_Kangaroo]

Try the condenser on the side of the distributor. I use to carry a spare just in case it presented similar issues to what you have described. I also had friends with e21's that had the same problem.

[amdavidson]

Well, I had success and then dramatic failure last night.

I tried to check the timing, but for the life of me could not find the notches on the engine or pulley. Does anyone have advice as to what angle to look at to best see these? Any angle I check is covered with water hoses or fan shrouds. Any photos or images out there?

I then adjusted the timing by ear and got it running pretty well, but it felt like it was a little over retarded on a drive despite no major issues. I pulled her back into the garage and adjusted the timing again.

But by the time I got her to the end of the street she had stalled and despite my best efforts to adjust her timing back, I couldn't get her started again.

Any advice as to how to get to ground zero on the timing so I can readjust?

[amdavidson]

Well, the issue was traced back to a condenser wire that fell apart during the adjustment of the timing.

The car is now running well, and the timing settled.

Thanks to all who posted.