41 Distributor Inner Cap Issue

Trelpdx

Trelpdx

Senior Member
Guys,
I've been pulling my hair out as to why I can't get spark on my 41 V8. New points, distributor set up on machine, coil checked out good, new condenser, and new solid core wires. Just finished complete rebuild of Dads old hot rod engine. Anyway, I thought I'd check the continuity from the electrode of the inner cap out to the plug connection. Only 1 out of 8 had continuity so I pulled out all the plug wires from the back of the inner caps and tested continuity there. Again, only 1 out of 8 had continuity across the cap. These are brand new caps I'm sure made in China. Am I missing something? There should be 100% continuity across these caps, correct? Some of them I could measure resistance across and others wouldn't measure any resistance. Did I just get a hold of bad caps and this is my problem or am I looking at this wrong?


Thanks much,
Peder
 
Where did you get your caps from? We’ve seen serious issues out of the macs antique auto, caps.


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Trel.
Not sure where yours were made but even those sold by long time vendors who we all know and respect are problematic. A respectable vendor will accept returns for cause. Having said that....when I get a shipment of inner caps I check each one with a simple continuity light. For any terminals showing no continuity I use a nylon tap
hammer and gently tap the terminal 'home'. In most cases continuity is restored.
That's how I do it.
Charlie ny
 
I don't do much work on the pre 1942 distributors, but I pick up all the nos and good used v8 ignition parts I can at swap meets and sales . More often than not they are better than the cheap stuff we're getting today. I usually carry an ohm meter with me.
 
fordwife said:
I don't do much work on the pre 1942 distributors, but I pick up all the nos and good used v8 ignition parts I can at swap meets and sales . More often than not they are better than the cheap stuff we're getting today. I usually carry an ohm meter with me.
Click to expand...

This is exactly what I have done. I've bought, and otherwise aquired a good number of '33 thru '41 used distributors, and completely dismantled all of them for parts. Many of these had new point sets, rotors, inner caps, capacitors, etc. This gave me enough good parts to rebuild as many distributors as I'll ever need.

Trelpdx said:
Guys,
I've been pulling my hair out as to why I can't get spark on my 41 V8. New points, distributor set up on machine, coil checked out good, new condenser, and new solid core wires. Just finished complete rebuild of Dads old hot rod engine. Anyway, I thought I'd check the continuity from the electrode of the inner cap out to the plug connection. Only 1 out of 8 had continuity so I pulled out all the plug wires from the back of the inner caps and tested continuity there. Again, only 1 out of 8 had continuity across the cap. These are brand new caps I'm sure made in China. Am I missing something? There should be 100% continuity across these caps, correct? Some of them I could measure resistance across and others wouldn't measure any resistance. Did I just get a hold of bad caps and this is my problem or am I looking at this wrong?
Thanks much,
Peder
Click to expand...

This situation has been reported several times, over a span of years, here on Fordbarn and from other sources on the internet. Best thing you can do is check these inner caps 100% before using anything. Charlie ny's fix sounds feasable to me.
 
Wow this could very well be a tough one .......

LET ME START BY SAYING THERE SHOULD BE CONTINUNITY BETWEEN THE CONNECTOR AND THE TERMINAL !!!!!

However that more than likely WONT cause a no spark etc !!!

If ya checked hundreds of caps ( mac Van Pelt wrote a article o these once) many will not have good ohm meter continunty between the connector and terminal tip .
Assembly methods may not complete this circuit but actually its just a added gap in the secondary circuit that the system should be able to jump and would add to the spark of put of the coil.

Not saying this is good just saying thats the way it is ! Ever pulled a coil wire loose just a little to start a flooded engine , same action here . a booster gap spark plug used for years had a added open gap in the electrode for better starting etc ....

The old Sun testers had a test checking the gap from rotor to wire end (without the wire) and you were allowed a loss of 2000 volts just in gaps BEFORE you got to the plug gap.!!

SO its a problem but not THE problem ...:eek:

So i got in a order of four new side caps from 3rd Generation Parts yesterday and had this customers distributor laying on the desk.
First of all every terminal (16 of them) checked very good at approx 0002 ohms with a fluke 88 ohmeter ( the best there is ) and the air gap is approx .015 on my customers unit . While we are discussing this voltage loss issue theres another fix you all should be using and that is a solid core wire with a brillman connector , every cap section or contact is machined for a snap connection and the brillman brass connector has the little notch to lock inside the cap . Go to brillman and buy a handfull then solder to the wire end .

If your going to be picky then be picky!!! :eek::eek::D

https://brillman.com/product/old-style-straight-soldered-high-tension-distributorcoil-terminal/
 

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Trelpdx said:
Guys,
I've been pulling my hair out as to why I can't get spark on my 41 V8. New points, distributor set up on machine, coil checked out good, new condenser, and new solid core wires. Just finished complete rebuild of Dads old hot rod engine. Anyway, I thought I'd check the continuity from the electrode of the inner cap out to the plug connection. Only 1 out of 8 had continuity so I pulled out all the plug wires from the back of the inner caps and tested continuity there. Again, only 1 out of 8 had continuity across the cap. These are brand new caps I'm sure made in China. Am I missing something? There should be 100% continuity across these caps, correct? Some of them I could measure resistance across and others wouldn't measure any resistance. Did I just get a hold of bad caps and this is my problem or am I looking at this wrong?

Ok lets start over , fully charged battery , whats the voltage to the ignition coil 1= ?? key on = ???? cranking = ????
Then pull a plug wire from plug and check for a sparking jumping to ground like the head etc ?? Does it have spark ??
what kind of condensor ??? What kind of coil ????
Need more info , maybe even a picture of distributor on engine ????
Always glad to help .......:eek:
Click to expand...
 
Too add to the caps, some of the one’s being sold out there the holes where the plug wires insert into, there is plastic molded around the sides of the holes and the brass is only visible at the bottom if that makes since. If yours are like that, you are not only have to arc across that gap, but also across the gap in the cap terminals
 
Bubba and Michael thanks for digging deeper. The solid core wires and SOLDERING the
ends to me is a given. I use an inexpensive test light to verify continuity from the spark
plug connector to terminal on the rotor side of the cap. It's not uncommon after
threading sp wires thru the conduits then persuading them thru the outer cap into the inner cap that one or more wires could be disconnected. Murphy's law.
Charlie ny
 
I have found lots of insulating material inside the plug wire terminals. I remove this insulating material to expose the brass terminal molded inside the cap. I don't want to introduce any more resistance in any plug wire circuit more than necessary. I would not use an cap with infinite resistance from one side to the other, on any of the terminals.
Ford list the rotor to cap terminal gap with Spec. they vary somewhat so I will not type them here but none are above 0.0125" for the 68-12201
 
Thank you for the responses. I plan to get some new inner caps tomorrow. The coil, which has been checked out, good, has the Ford logo on top. The condenser I have on now I bought because the guy who tested the coil & condenser told me that I had a bad condenser. It is now a Napa FA49. It bolts up right, but a little shorter than the original. The battery voltage is 6.5. With key on and points closed voltage is 3.5. I have a resistor under the dash. There is no spark from plug wires.
 
Sometimes the rotor center section will arc over to the inner shaft. If that happens there will be no spark at any plug. I have seen the rotor center section brass conductor crack at several places. This may give you spark at some plugs.
Also check Check the high voltage output end of the coil and make sure the carbon brush and spring are in place. The carbon brush rubs on the center of the rotor.
 
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