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One for you OLD School Mechanics

I had read that as well…I was going to hookup to the battery in my f150, unfortunately the leads on the timing light are way too short.

I jumped in a posted before reading all the excellent posts on this question. You guys are ahead of me… Or should I say behind me. It’s a 1950 model and that’s behind most of us isn’t it?

My next SWAG would be the accelerator pump. But I’m not familiar with that old Carter. Maybe the OP should read OOOLD school.

Fender can you post the specs you had for setting up your points/timing? This is what I can find online for your engine. Spark plug gap .035, point gap .016, idle speed in gear 375rpm(seems low to me), timing mark “c” for regular fuels, timing mark “A” for premium fuels, spark plugs AC48X, dwell angle 24-30 degrees. One other thing I thought of was an old timer told me years ago to only use brass feeler gauges when setting points. He had a reason that I have long forgotten, but I still set points with the brass gauges.


Use jumper cables. Just be sure you wrap the connections with something to insulate them so they don’t short out.

The light only needs the 12VDC to power the bulb. I honestly don’t know how the voltage spike peak on a 6VDC system stacks up against the spike on a 12VDC system, and thus how sufficient the inductance would be, but once you try it and post back I’ll have learned something! Some of the guys here who ride bikes might know the answer to the question of how well that’ll work. There are still a lot of 6VDC bikes on the road.

@SteveC76‌ All of your specs are correct and what I went by. These oldies like to idle LOWWWW. Took some getting used to. If you have it too high it will clunk harshly when put into gear. The car has no rpm gauge so we do it by feel. Basically making it low enough to run rough and shake, then bump it up just to smooth out and make her happy.

Not sure if you guys missed my question earlier…

If I remove the vacuum line off the distributor and it cures the problem, what does that indicate is going wrong?

It suggests that the ignition timing is set incorrectly.

Someone else here mentioned dwell. This setting is often critical on these old 6VDC engines and needs to be set with a dwell/tach. The dwell is the amount of time the coil primary has to build a magnetic field, and that effects the voltage induced into the coil secondary (the “spike”). That in turn affects the strength of the spark. You should be sure the dwell is correct too. A weak spike could easily cause an erratic idle.

So many tools to acquire! Add a dwell meter to the list. But I think its safe to say this 50 cad wont be my first classic. I really enjoy the old ones, and its oddly made me appreciate new tech as well. The convenience of turning a key and getting a smooth idle in any weather is nice. But the classics are alive!

Not to stir the pot but I’ll say it anyway. Originally I set the timing to the “C” mark. Got it running well, drove it fine, then it acted rough again. I checked the timing and it seemed to move 1/4". I decided to try the timing on A. Same scenario happened. What I ended up realizing is that the idle was not always returning to the EXACT rpm every time. Thus, an inaccurate timing reading. Perhaps the idle return spring is worn out?

It’s also possible that the distributor is worn out. Check the distributor shaft for lateral play and rotationally for play (wear) of the gears that drive it. Either would cause a wandering idle, and the first is actually common in old engines.

I agree with how possible it is…although I sure HOPE its not. These old caddy parts are rare and expensive. I forget but itd be in the neighborhood of $250 plus $100 core charge or something like that.

By the way, just wanted to say THANKS

Nice ride once you’re done, though.

Thanks - here it is


look down into the carb with the choke plate open and work the throttle linkage, you should see a strong spray of gasoline in both front bores. If you don’t your accelerator pump diaphragm is ruptured. On the linkage on the side of the carb you should see some holes to move the linkage to to give more or less spray.

Yeah they both spray well. I had checked that a few times when setting the choke.

Another possibility I had considered was vapor lock.

Does that old carter have a power valve?

Not sure what that is…im guessing not?

This doesn’t sound like vapor lock, that’s more of a problem when you drive it, park it, then try and start it.

Is the vacuum diaphragm in the distributor good? If it’s leaking, then you’ll have a vacuum leak, which may explain why the problem goes away when you disconnect the vacuum advance.