The Stovebolt Site Forums The Shop Area The Electrical Bay no dwell

I am trying to get my 59 half ton running (235). It turns over but no spark. It was suppose to be a recent rebuild (buy the guy before the guy I got it from). The relatively clean oil and plugs indicate it was at least worked on. A little carbon on the plugs makes me think it ran for a while. I needed to set up my own wiring so I used a VW ign switch mounted to the front of the car so I could turn the key and see what was happening at the same time. I did not put the resistor in the sequence because I think it takes all 12 volts to start then switches to the alt output through the resistor to run and save the points. Is that correct? Anyway it has no spark. The dwell meter pegs out and says no dwell so the current is running all the time, even when the points are open. I get a spark at the points when I short them. Is there a process of checks to determine if the coil, condenser and points are all working correctly?


Jim

Jim,

I think the easiest thing for you to do would be to set the points with a feeler gauge, stick the system back together and make sure you have power to the key side of the coil, then attempt to start the truck as you hold a plug wire near a good engine ground. Hold it about 1/4" off of ground and look and listen for a nice crackling spark.

If you have a meter, your readings from coil + to ground should be around 9 volts if you have ballast resistor in the circuit. This reading is with the key on, engine stopped. The voltage from coil - to ground with the points OPEN should be about the same. When the points open, this reading should drop to ZERO.

It almost sounds like you are getting lost in "diagnosis land". If you manually set the points correctly, then do the spark plug ZAP test, you will quickly know if you have power to the plugs.

Your jury-rigged ignition switch might have you wired wrong...is that possible?

Stuart

Hey Jim, no dwell means the points are not opening.Does the rotor turn when you crank it over? If it does,crank it over and look at the points.Do they open and close ? Adjust the points to open on the high spot of the lobe and connect a jumper from the positive side of the battery to the + side of the coil.Start her up !!!
When you rewire it,the resister is wired to the "run side" of the ignition switch to coil and is by passed through the yellow wire at the starter,not the alternator.

Thanks, the points open and close. The rotor turns and even when I hold the points open with a plastic knife the dwell pegs out

thanks, I did the zap test. no spark. I have a circ. tester with a light but not a volt meter. the light lights up with the ignition on at the coil. I can get a spark when I short the points. Will a bad condenser cause the dwell to show continuous elec flow even with the points gapping?

Jim,

Dwell is the number of degrees the distributor cam rotates while the points are closed..the coil is saturaing or 'charging'. Although this is relavent when the engine is running, I think you need to stick the dwell concern on the back burner and get back to a primitive hands on approach, gapping with a feeler gauge, that's the starting point.

A shorted condenser can cause this problem. You need to use your meter or tester and verify proper voltage all the way to the points.

Stuart

When you short across the points you should get a spark out of the coil. If you do then the points are not making contact. They may be burned a little or you got grease or dirt on them. If you get spark at the points but not the coil then the coil or cond. are bad.