The Stovebolt Site Forums The Shop Area Engine Shop Nearing wits end

I have a 1956 3100 with a 235. It was running well until one evening when it suddenly started running really rough. Pushing the accelerator would provide no power, and nearly stall it out. It sounded like carb/ignition stuff. So I was able to cajole it into my garage. I rebuilt the carb, replaced points,plugs,wires,condenser,distr cap, retuned it and it ran like a champ for several weeks!

Until last Wed. The same issue. Stalled out, couldn't get it started, or if I somehow managed to start it it ran real rough until it stalled out. So I towed it back home. I checked spark off of the coil and it looked weak (orange and intermittent). I checked coil output and it was weak (I can't remember which reading) so I replaced the coil, and the condensor again just for kicks. The spark was still orange, but steady. But it still won't even start. I did notice an unusual wear pattern on the new points (a little wear on the rear bottom contact) so I figure I will replace those 2 week old points this weekend.

I thought it might be dirty fuel so I checked the gas in the float chamber and the fuel looked clean. But I will install a fuel filter this weekend anyway.

I am still very new to this hobby and am learning by doing, and I would greatly appreciate other things that folks might suggest I check. This machine has run really well for many years. Thanks very much for any hints.

Did you align the points when you installed them and put a little grease on the rubbing block. I would install a new condenser and make sure you got the polarity on the coil right. On a Chev, the - goes toward the distributor and the + to the ballast resistor.

another thing worth checking is the vent on the tank just incase its vacuming after running awhile
i had a motor at work where the fuel system was still under vacume days after it had been towed in dead . nobody could get it to run ,, untill i took the filler cap of and tried it ,,once it had pulled fuel through it ran fine ,,

I would take a look at the wire terminals that go to the coil and to the distributor. Also check the insulator that goes through the side of the distributor to make sure its not falling apart and causing the stud to intermittently short against the body of the distributor.

The first thing I would check is to see the amount of fuel delivery at the carb. Specs are in the manual. Even a weak spark will fire an engine but no fuel delivery equals a no start.

Thanks for those thought starters. A fun weekend is lined up for sure!

Squirt a little fuel down the throat of the carb. If it then fires, you have a fuel delivery problem. Just because something is new does not mean it is good. This past summer, I purchased a Corvair in a non running condition. I went ahead and replaced all the ignition components before attempting the first start. I would start and run, but a soon as it got warm/hot, it would die and not restart until it cooled down. Replaced condensor and coil again and the problem went away.

Sound like maybe your ballast resistor has failed. The old points system used a ballast resistor to reduce the voltage across the points to keep them from burning up too fast. The wear pattern would be excess metal on one point contact and a matching depression on the other point contact.

That wear pattern throws the timing off and cause the engine to run rough or not at all.

It looks like this and is usually mounted on the firewall, although I have seen them hanging off the coil, off the distributor and other locations (all bad ideas - the resistor is very subject to failure due to vibration - which is why they mounted it on the firewall.)

If you have an ohmeter, it should be about 1.5 ohms or so. If you have a voltmeter, you should see the voltage to the points drop once the engine is started. The purpose of the ballast resistor is to reduce the voltage to the coil's primary side (and therefore to the points as well) to reduce wear and tear on the points. High voltage sparks tend to melt the metal on the points, causing the transfer from one point contact to the other.

Trash in the fuel tank?

I am going to try both of the fuel ideas. And I have a new ballast resistor on order to replace it as well. I will also replace the points and condenser again, after replacing the resistor. A lot of ideas. Thanks everybody so much. I greatly appreciate the tips.

and remember that coils must be matched to whether or not you have a ballast resister. Some coils have built in resistance and some do not. Ensure you are using a coil that does NOT have built in resistance since you are using the ballast resistor.

Thanks David. I believe I have that covered. I bought a resistor from Classic Chevy. It didn't have an ohm rating but can I assume it is the correct resistance for my coil? It was listed as working with the 56 so I assumed I'm ok. But you know what they say about assume...

Ray, it'll be the right resistance, there's only one

Bill

I had same issue, got rid of ballist resistor and got a coil with built in resistor. no more problem. i did convert to 12 volt though

I am going to have a great weekend! Points, condenser, fuel pump and filter, resistor and coil. I may even swap out the sending unit if I have time before the Ravens game! Come on weekend.

The truck is running great now. Thanks to everybody for their help. Turns out it was the coil. A buddy came over and we were going to start going through the list of additional items to fix. We popped open the hood and were poking around. Then he looked over at the battery and said, "hey, what's this rotor doin' sitting on top of the battery?" I burst out laughing. After I replaced the coil and condensor, I forgot to put the rotor back in when I reassembled the dang thing. Who knew these vehicles need that little dongle type thing! At least now I know how the truck sounds when you try to start it without the rotor cap! Thanks again, everybody?

thanks for the update, as they say, things happen,
they also need gas to run

Thanks for updating this, might help some else some day.

At least your team won.

Hilarious!

Had the same thing happen once, trying to get a faultering fire engine to run. Buddy had pulled the rotor in the trouble-shooting process. After a half-hour of messing around and turning it over, he reached into his pocket, pulled out the rotor with a sheepish grin, and said,

"I wonder if putting this back in would help?"

Gotta laugh, or you may start cryin'!

-Michael