I'm so frustrated, as I'm trying to make my car more dependable, I've made it just the opposite. I have a 48 59a in a sedan. I've been getting an intermittent misfire when it rains so I assumed ignition. I still have 6v positive ground, with a Petronix module in the distributor, and Petronix coil. I've been reading on here that with the Petronix I should not use solid core plug wires. So I decided to switch to a crab cap and rotor. I bought an A/C delco cap F381, A/C Delco rotor F444, and Petronix 708180 wires. I put them in today, used the Van Pelt diagram for intallation. I go to fire it up and it just cranks, I verified I have fuel squirting down the carb. What did I miss?
Installed a crab cap, now no spark
- Thread starter Chappy
- Start date
BUBBAS IGNITION
Well-known member
You have spark at coil wire ???
supereal
Well-known member
I suspect you have the wrong rotor. The part number for the "crab" distributor cap rotor is 21A-12200. You likely have the 59A type in your distributor. I have never completely understood why a crab type setup is desired, unless you have a '42. It was a one year type but was discontinued because of problems with water. Granted, it is a simpler cap than the two part later type, but properly assembled, the later cap is more dependable.
Dumb question but would that be a constant spark?
Quite often the rotor tab strikes the contacts in the cap due to misalignment or wrong rotor and breaks the rotor. Just pull the cap and look at the rotor.
Bill
Lawson Cox
Well-known member
And the contact points in the cap. Did you make sure rotor cleared the points in the cap before buttoning it up? If not, you can bust a rotor or cap, or both. Don't ask me how I know.
BUBBAS IGNITION
Well-known member
How about the wrong rotor??? 42 and 48 use different rotors, one short ( for the rabbitt ear cap) and a longer one for the crab cap???
When ya said delco it scared me as to the correctness of the parts..
When ya said delco it scared me as to the correctness of the parts..
1942deluxe
Well-known member
Chad, as mentioned make sure you have the rotor for the 42 and not 46-8. Also make sure it is seated all the way on the shaft. Tell Susie Happy Birthday.
For those of you who said broken rotor, you are correct. I ordered the parts off of amazon for a 1942 car, it's a convenience using it. Foolishly I didn't check clearance when i had the distributor out to switch the cap clamps, honestly of all the cars (mostly newer than 1970) I've ever replaced cap and rotor on, I've never checked clearance, and they always worked. For now I put the V cap and rotor back on until I can get the proper rotor. Thanks for the help, and Uncle John I told Susie, thanks.
Walt Dupont--Me.
Well-known member
I've had a lot of rotors from Ford parts places, you know who I mean, I broke a couple yr's ago, from then on with the dist on the bench I carefully install the rotor and cap and turn the dist by hand, a lot of times you can feel the rotor hitting the **** in the cap, if so grind off a little on the end of the rotor. I wish there was a way to see through the cap. Walt
Walt Dupont--Me.
Well-known member
It;s probably 6 to one or 1/2 doz the other, I wish there was a way to see through the cap. I think Babba said .025 gap is ok. Walt