The Ford Barn

Chappy · 07-04-2015, 04:09 PM

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?

JSeery · 07-04-2015, 04:24 PM

My first guess would be you don't have the wires in the correct locations, but hard to see how that could happen.

BUBBAS IGNITION · 07-04-2015, 04:31 PM

You have spark at coil wire ???

supereal · 07-04-2015, 04:41 PM

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.

Chappy · 07-04-2015, 04:56 PM

Quote:

Originally Posted by BUBBAS IGNITION

You have spark at coil wire ???

Dumb question but would that be a constant spark?

bbrocksr · 07-04-2015, 04:58 PM

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Quote:

Originally Posted by Chappy

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?

Broken rotor!
Bill

Chappy · 07-04-2015, 05:04 PM

Bill what makes you think that, and is there a way to test it?

bbrocksr · 07-04-2015, 05:33 PM

Quote:

Originally Posted by Chappy

Bill what makes you think that, and is there a way to test it?

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 · 07-04-2015, 07:42 PM

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.

Chappy · 07-04-2015, 07:51 PM

I'll check that stuff out tomorrow, thanks for the input guys

BUBBAS IGNITION · 07-05-2015, 09:09 AM

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..

1942deluxe · 07-05-2015, 12:05 PM

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.

Chappy · 07-05-2015, 12:22 PM

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. · 07-05-2015, 03:23 PM

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 tits 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

scooder · 07-05-2015, 05:18 PM

Walt,
Is the issue the rotor being too long or the cap tits not concentric with the cap mounting? So the tits on one side are touching but opposite s too large a gap?
Martin.

Walt Dupont--Me. · 07-05-2015, 06:25 PM

Quote:

Originally Posted by scooder

Walt,
Is the issue the rotor being too long or the cap tits not concentric with the cap mounting? So the tits on one side are touching but opposite s too large a gap?
Martin.

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

07-04-2015, 04:09 PM	#1
Chappy Member Join Date: Nov 2014 Location: Rochester, NY Posts: 55	Installed a crab cap, now no spark 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?

07-04-2015, 04:24 PM	#2
JSeery Member Emeritus Join Date: Nov 2012 Location: Wichita KS Posts: 16,132	Re: Installed a crab cap, now no spark My first guess would be you don't have the wires in the correct locations, but hard to see how that could happen. Last edited by JSeery; 07-04-2015 at 04:30 PM.

07-04-2015, 04:31 PM	#3
BUBBAS IGNITION Senior Member Join Date: May 2010 Location: SPEEDWAY INDIANA Posts: 4,148	Re: Installed a crab cap, now no spark You have spark at coil wire ??? __________________ If it Makes Spark, we do it !!!! www.bubbasignition.com [email protected]

07-04-2015, 04:41 PM	#4
supereal Senior Member Join Date: Jul 2014 Location: Iowa Posts: 1,634	Re: Installed a crab cap, now no spark 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.

07-04-2015, 05:04 PM	#7
Chappy Member Join Date: Nov 2014 Location: Rochester, NY Posts: 55	Re: Installed a crab cap, now no spark Bill what makes you think that, and is there a way to test it?

07-04-2015, 07:42 PM	#9
Lawson Cox Senior Member Join Date: May 2010 Location: Above the gnat line in Georgia Posts: 7,009	Re: Installed a crab cap, now no spark 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. __________________ Life is like a roll of toilet paper. The closer to the end, the faster it goes. It is better to be seen, than viewed. "We sleep safe in our beds because rough men stand ready in the night to visit violence on those who would do us harm".

07-04-2015, 07:51 PM	#10
Chappy Member Join Date: Nov 2014 Location: Rochester, NY Posts: 55	Re: Installed a crab cap, now no spark I'll check that stuff out tomorrow, thanks for the input guys

07-05-2015, 09:09 AM	#11
BUBBAS IGNITION Senior Member Join Date: May 2010 Location: SPEEDWAY INDIANA Posts: 4,148	Re: Installed a crab cap, now no spark 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.. __________________ If it Makes Spark, we do it !!!! www.bubbasignition.com [email protected]

07-05-2015, 12:05 PM	#12
1942deluxe Senior Member Join Date: Jan 2011 Location: Albion, PA Posts: 708	Re: Installed a crab cap, now no spark 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.

07-05-2015, 12:22 PM	#13
Chappy Member Join Date: Nov 2014 Location: Rochester, NY Posts: 55	Re: Installed a crab cap, now no spark 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.

07-05-2015, 03:23 PM	#14
Walt Dupont--Me. Senior Member Join Date: May 2010 Location: Gardiner Me. Posts: 4,200	Re: Installed a crab cap, now no spark 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 tits 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

07-05-2015, 05:18 PM	#15
scooder Senior Member Join Date: Jul 2010 Posts: 2,593	Re: Installed a crab cap, now no spark Walt, Is the issue the rotor being too long or the cap tits not concentric with the cap mounting? So the tits on one side are touching but opposite s too large a gap? Martin.