The Ford Barn

Veeder · 06-25-2017, 05:26 PM

I currently have 4 distributor Caps and when I am checking between the Pin (which comes in contact with the Rotor) and the socket that the plug wire would be inserted into and a number of them have no continuity or approx. .6 ohms -- 2 ohms of resistance.

The question is are these prone to these types of failures I really expected them to be a dead short when testing or open ckt not the .5 ohms stuff and does it matter. I haven't cut one open yet but likely will

thanks in advance

Jim in Wisconsin · 06-25-2017, 07:02 PM

Are these old used ones or new repoductions? I have seen new repos that had no continuity - that's no good. A small amount of resistance probably won't matter much. It would be interesting to cut one apart - I would think there should be a copper or brass strip connecting the tip to the socket.

JSeery · 06-25-2017, 08:01 PM

There should be near zero resistance, as you said, dead short.

Veeder · 06-25-2017, 08:53 PM

These are repoes I assume as there are no markings on them but I drilled out all four wire sockets the pin is off to one side of each wire socket and it appears each one the pins is just a press fit agaiast the bottom outer edged of the socket that holds the wire in. Therefore everey time you pull the wires out you potential disturb the connection. I decided to fill the lower cavity with solder and it did the trick. Absolute junk that we buy these days!! I think tomorrow I will try to fill the void up a bit with thin wire and solder the others. One other thing just as a test on a different cap knowing now what I know I tapped in the pin lightly and that fixed the issue.

Mac VP · 06-26-2017, 04:55 AM

We've found that a small percentage of the new 37-41 type terminal plates we get in have this issue. We now test EVERY plate before they are put in stock. There can be small variances in resistance but all have continuity.

I've heard of the "fix" of tapping the contact down a bit to gain continuity......and that probably works fine, but we don't do any of that with our new terminal plates.

BUBBAS IGNITION · 06-26-2017, 05:29 AM

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This has been discussed here before as someone cut a few of the early side caps like Mac said in post above and found open circuits. However secondary resistance is different than primary resistance as the voltage is so high. An example found on a scope is the engine idling uses approx 5,000 volts to fire the plug (voltage required) and the coil has 20,000-30,000 volts (available) The reserve in this example would be 25,000 volts (reserve). A gap in the contact (open) may use anywhere from 200 to 800 more volts to jump the gap.
Not desired but not a problem either. In the early 70s some caps came on the car with a E gap ( emissions) to try to clean up the spark. Anyome remember the old plastic JC whitney spark boosters that fit in the cap or coil wire (that was just a gap to slightly increase the spark.) ???????????????????????

Veeder · 06-27-2017, 07:41 PM

Very helpful guys and confirmed some of my thoughts two questions

1)What is an acceptable gab between the rotor and the contact pin on the inner cap

2)Assuming I had some burnt points and the car was barely running (in an attempt to get it home) the plugs got all coated with carbon. How much does the carbon coated plugs influence the ability for the spark to jump the gaps being discussed here. If I had a scope and felt better would love to experiment with this.

06-25-2017, 05:26 PM	#1
Veeder Senior Member Join Date: Dec 2012 Location: CT Posts: 394	41 stock V-8 Distriburtor Cap questions I currently have 4 distributor Caps and when I am checking between the Pin (which comes in contact with the Rotor) and the socket that the plug wire would be inserted into and a number of them have no continuity or approx. .6 ohms -- 2 ohms of resistance. The question is are these prone to these types of failures I really expected them to be a dead short when testing or open ckt not the .5 ohms stuff and does it matter. I haven't cut one open yet but likely will thanks in advance

06-25-2017, 07:02 PM	#2
Jim in Wisconsin Senior Member Join Date: Jan 2012 Posts: 247	Re: 41 stock V-8 Distriburtor Cap questions Are these old used ones or new repoductions? I have seen new repos that had no continuity - that's no good. A small amount of resistance probably won't matter much. It would be interesting to cut one apart - I would think there should be a copper or brass strip connecting the tip to the socket.

06-25-2017, 08:01 PM	#3
JSeery Member Emeritus Join Date: Nov 2012 Location: Wichita KS Posts: 16,132	Re: 41 stock V-8 Distriburtor Cap questions There should be near zero resistance, as you said, dead short.

06-25-2017, 08:53 PM	#4
Veeder Senior Member Join Date: Dec 2012 Location: CT Posts: 394	Re: 41 stock V-8 Distriburtor Cap questions These are repoes I assume as there are no markings on them but I drilled out all four wire sockets the pin is off to one side of each wire socket and it appears each one the pins is just a press fit agaiast the bottom outer edged of the socket that holds the wire in. Therefore everey time you pull the wires out you potential disturb the connection. I decided to fill the lower cavity with solder and it did the trick. Absolute junk that we buy these days!! I think tomorrow I will try to fill the void up a bit with thin wire and solder the others. One other thing just as a test on a different cap knowing now what I know I tapped in the pin lightly and that fixed the issue.

06-26-2017, 04:55 AM	#5
Mac VP Senior Member Join Date: May 2010 Location: Cincinnati, OH Posts: 1,361	Re: 41 stock V-8 Distriburtor Cap questions We've found that a small percentage of the new 37-41 type terminal plates we get in have this issue. We now test EVERY plate before they are put in stock. There can be small variances in resistance but all have continuity. I've heard of the "fix" of tapping the contact down a bit to gain continuity......and that probably works fine, but we don't do any of that with our new terminal plates. __________________ VANPELT SALES LLC Cincinnati, Ohio Office: 513-724-9486 www.vanpeltsales.com www.classictransmission.com

06-26-2017, 05:29 AM	#6
BUBBAS IGNITION Senior Member Join Date: May 2010 Location: SPEEDWAY INDIANA Posts: 4,148	Re: 41 stock V-8 Distriburtor Cap questions Sponsored Links (Register now to hide all advertisements) This has been discussed here before as someone cut a few of the early side caps like Mac said in post above and found open circuits. However secondary resistance is different than primary resistance as the voltage is so high. An example found on a scope is the engine idling uses approx 5,000 volts to fire the plug (voltage required) and the coil has 20,000-30,000 volts (available) The reserve in this example would be 25,000 volts (reserve). A gap in the contact (open) may use anywhere from 200 to 800 more volts to jump the gap. Not desired but not a problem either. In the early 70s some caps came on the car with a E gap ( emissions) to try to clean up the spark. Anyome remember the old plastic JC whitney spark boosters that fit in the cap or coil wire (that was just a gap to slightly increase the spark.) ??????????????????????? __________________ If it Makes Spark, we do it !!!! www.bubbasignition.com [email protected]

06-27-2017, 07:41 PM	#7
Veeder Senior Member Join Date: Dec 2012 Location: CT Posts: 394	Re: 41 stock V-8 Distriburtor Cap questions Very helpful guys and confirmed some of my thoughts two questions 1)What is an acceptable gab between the rotor and the contact pin on the inner cap 2)Assuming I had some burnt points and the car was barely running (in an attempt to get it home) the plugs got all coated with carbon. How much does the carbon coated plugs influence the ability for the spark to jump the gaps being discussed here. If I had a scope and felt better would love to experiment with this.