Yikes! No spark! Need some trouble-shooting advice

B

Big_Guys_baby

Senior Member
Hey Gang, I need some help!

Reinstalled my rebuilt distributor courtesy of bubbas. Easy install job, she lined right up with no problems. Replaced the distributor cap (one from carpenters) but just the lower cap since the old rotor and worn distributor had damaged it. Spark plug wires and upper cap are about 5 years old and have about 20 miles on them total. new rotor was on from bubba's.

There is no spark getting to the plug wires whatsoever. I think it must be something fairly obvious and simple, I am just a bit frustrated right now with it.

Some troubleshooting procedure would be great, all advice welcome.

Thanks!

Jeff
1946 Biz Coupe
 
First (and easy) things to check are:

1) Is there voltage on the hot side of the coil with the ignition on?
2) Does the voltage on the coil's low side (the wire that goes to the distributor) bounce up and down while cranking?

Tom
 
Yes to to voltage on the Hot side of the coil. When I used the test light on the distributor side there was no voltage, but didn't try while cranking. Doing to grab my mulitmeter from work and check it out tonight.

Assuming that there is voltage at the coil (I also did the cursory coil swap just in case as well) what is next?
 
While cranking, the distributor is intermittently grounding the coil's low side terminal. If you don't see that, then it could be the points, or some other failure in the distributor (yes I know its just been rebuilt, but things happen), or possibly the wire from the coil to the distributor is open.

If you do see the low side coil voltage varying while cranking then pull the coil hot lead and stick a piece of wire into it and see if you can draw a spark to ground while cranking. Or perhaps pull the coil's hot lead at the distributor and hold that end near to ground.

No spark there says it's a coil or hot lead problem. If you do see a spark, then it sounds like something in the rotor or cap.

Tom
 
big_guys_baby said:
yes to to voltage on the hot side of the coil. When i used the test light on the distributor side there was no voltage, but didn't try while cranking. Doing to grab my mulitmeter from work and check it out tonight.

Assuming that there is voltage at the coil (i also did the cursory coil swap just in case as well) what is next?
Click to expand...

remove coil wire from cap and hold to ground ( 1/4 inch or so) and crank engine. If it now sparks check the rotor.

very unusual for me to install a 46 small rotor for a rabbit ear cap.

i could have used the flat cap (one piece) rotor . Havent had that happen before but you stated you bought a new lower cap making me think you have the rabbit ear cap set up which uses a different rotor....
 
Thanks Bubba's! Will check that out tonight. The car definitely has a two piece distributor cap setup, with the inner piece and the outer piece that has the plastic V shaped channels that the wires run through.

I didn't look closely at the rotor before I installed because I was excited to get her back on the road.

Does the Napa part number FA67 work as a rotor on that type of cap? There is a napa nearby that keeps them instock.
 
Update! She runs! It had the correct rotor and spark to the distributor. Pulled off the new inner cap, put old cap back on. Meticulously inspected every connection with multimeter, cleaned spark plugs and she fired right up!
 
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