11 cab CMP Distributor question

[MikeV]

Hello Everyone
I am a looking for a bit of help. I am a member of the ONTR museum in Oshawa and we are rebuilding a 11cab ford v8 we are at the point of trying to check for ignition to the spark plugs, but the clam shell distributer which is on the front of the motor ( had to remove every thing to get at it.)
Looks like it has a bit of wear to the contacts . we cleaned up the contacts and tried an ohmmeter on the contact inside the cap to the plug connection. Should I get a reading to show it will carry voltage or will we have to hook everything up and hope for the best ?
All the wires look original and so is the dist. cap. we have replaced the coil and set and cleaned the points and rotor.

[Tony Smith]

That is not an original 11 Cab distributor, it is called a 59A and was fitted to post-war engines from '46 to '49. Due to it's distinctive cap, it has the nickname of "Rabbit ears". The distributor itself is essentially the same as the '42 to '45 "Crab cap" distributor. The original type was a 3 bolt "Diver's Helmet".

I am not sure exactly what you mean by the rest of your question. Are you asking if there should be electrical continuity between the inside terminals on the cap and the outer sockets where the Ign leads fit? Certainly should be!

[Lynn Eades]

I may have this wrong, but I think one set of points establishes the dwell and the other set triggers the spark. To check continuity through each set of points, you need to insulate/ isolate the other set of points by putting a piece of paper between the contacts. I hope that helps.
I have a timing jig, but could not figure out what I was doing. I had already ordered a Pertronix for it along with their coil. I installed them and the engine has never missed a beat.

[Brian Butt]

I'm the other half of the 15 cwt team at the Ontario Regiment Museum. We know the truck has a post war engine, but didn't know from what year, so '46 to '49 seems about right. Besides the engine, we know the transmission came out of a civilian truck, because the shifter is way too long, (Ape hanger comes to mind), I'll include some other pics, when I get a chance.
The other part of Mike's question was regarding continuity through the plug wires; We hooked up an Ohm meter, with one probe on the inside cap terminal for one of the cylinders, then the other probe to the clip that goes on the plug. No matter which wire we moved the probe to, it still indicated an open circuit. Shouldn't we be getting some sort of reading?
Now, if the plug wires are pooched, where could we get replacements?

[rob love]

The best wire to use is the steel core 7mm wire on these older systems. NAPA ha a semi tailored set, part number 700170 for around $63 ($45 if you are in the trade) that work fine, or you can order the wire in a spool and buy the ends in either bulk or individually. Personally, I buy it in bulk.

Napa also has the points set (CS47) but they aren't cheap at $65 ($40 trade).


You can likely get the stuff a bit cheaper thru specialty shops like Dennis Carpenter or Mac's.

[Brian Butt]

I'm the other half of the 15 cwt team at the Ontario Regiment Museum. We know the truck has a post war engine, but didn't know from what year, so '46 to '49 seems about right. Besides the engine, we know the transmission came out of a civilian truck, because the shifter is way too long, (Ape hanger comes to mind), I'll include some other pics, when I get a chance.
The other part of Mike's question was regarding continuity through the plug wires; We hooked up an Ohm meter, with one probe on the inside cap terminal for one of the cylinders, then the other probe to the clip that goes on the plug. No matter which wire we moved the probe to, it still indicated an open circuit. Shouldn't we be getting some sort of reading?
Now, if the plug wires are pooched, where could we get replacements?

[Brian Butt]

Thanks Rob, that will get us going in the right direction.

[Harry Moon]

Given the nature of the project, I would recommend if the budget permits, Petronix ignition and coil. Maintenance free after that. especially given how hard it is to get to the points.

[Lynn Eades]

But if you go the Pertronix way, there should be at least one resistor lead. Either the coil lead or the six plug leads, or preferably a full set. I bought a set from Magnacor.
It's not about radio suppression, but about cross fire (induction of a spark in the wrong lead (EMF?))

[MikeV]

So with the electronic system it makes sense to use it , since the vehicles sit for extended times with out running except for events at the museum.

But wouldn't we need to install crankshaft sensors and since we have a franken truck so to speak.

Wouldn't we need serial numbers off the engine to get the right parts?

[MikeV]

Here is another view with the distributor cap on the motor! before we removed the distributor

[MikeV]

Here is a picture I took as we started the work, you can see we have some of the hood off to get at the engine. We did the easy part first the carb and fuel pump. I kinda like the truck it has Character . Can't wait to get it running.

[Tony Smith]

Originally Posted by MikeV

So with the electronic system it makes sense to use it , since the vehicles sit for extended times with out running except for events at the museum.

But wouldn't we need to install crankshaft sensors and since we have a franken truck so to speak.

Wouldn't we need serial numbers off the engine to get the right parts?

I think you're approaching this with a "Modern Car" mindset. WW2-era vehicles remained unchanged for years at a time, and even then many parts were common to a lot of variations.

The "Rabbit Ears" distributor has exactly the same internal parts as the wartime "Crab Cap" distributor. In fact, as a museum piece you might light to consider changing the bails and cap to revert the distributor to a wartime appearance.

But for this discussion (for the '42 to '49 distributor), the only info you need to find the correct Pertronix ignition unit is the electrical set up of the truck; 6 or 12 Volt, positive or negative earth.

Some examples HERE

Perhaps one of the users on here of the Pertronix unit could provide a quick write-up or photos of the modification?

[rob love]

Dennis Carpenter sells some reasonably priced electronic conversion kits for these distributors in either pos 6 volt or neg earth in 12. They note that you cannot use the solid core wire with them, so that will be something to consider.

https://www.dennis-carpenter.com/en/...ition-sys-6-vo
https://www.dennis-carpenter.com/en/...ition-sys-12-v

[Lynn Eades]

I have done my carrier. It is 12 Volt, Negative earth.I used the igniter kit, 1285LS it works for 42 to 48 Ford V8. Then you need a coil (the resistance is important) so the Pertronix coil number is #40011. The ignitor senses off the cam lobes (and so lobe condition is not important.
With the original system even NOS coils are very unreliable. (any doubts, ask Tony) Modern condensers are apparently the same,(buy three to get a good one?) and I have heard bad things about modern contact sets. From what I have heard the old points are better and having been used, hold their setting, whereas a new set will likely need adjusting after little use. (pull distributor out again)
The Pertronix doesn't have a condenser, so all in all, when you find that you have to change a lot of components, it might well save a lot of grief to go electronic.
As Tony says, you need to decide voltage and polarity as a first step.
Brown caps are supposedly better than black.
In this area, I wouldn't go back.

[Harry Moon]

This summer I installed the Petronix and blaster coil as a set , easy and simple. I'm going to upgrade the leads this winter although I didn't have any issues.

[MikeV]

Thanks for all the input on this subject
The Truck Is a 6 volt negative ground. Brian and I are a long way from the
finish line.

We have to replace the ape hanger shift lever we are both 6ft tall so when you put it in reverse you bang your elbow.
We have to change the crankcase oil it is black with a fresh blood. so we have a ways to go. Hoping after our repairs on the M8 Greyhound. (doing the brakes).

And first parades for remembrance day, we will get back at our favorite project.
We also have to put a new tail gate in and a grab bar on the roof opening .
Plus a lot of other minor things. I will post pictures when we progress further.
Once again thankyou for all your help.

[Bruce Parker]

Originally Posted by MikeV

The Truck Is a 6 volt negative ground. Brian and I are a long way from the finish line.

It was originally 6V positive ground. I hope al the appropriate conversions took place if it is negative ground.

[MikeV]

Originally Posted by Bruce Parker

It was originally 6V positive ground. I hope al the appropriate conversions took place if it is negative ground.

Sorry I am Mistaken, Yes you are right it is a positive ground. In Saying that we do have a few lighting bugs to Iron out as well. But our horn works LOL.

[Stew Robertson]

my recommendation is make it original
they worked all through the war and for 75 years later and in 15 minutes you can have it running .We found one parked under a pile of rails for 30 years and new fuel and a set of points and it was running .you can bet your bottom dollar that the electronic stuff will not work like that

[rob love]

Stew: While I, of course, admire and respect the old systems, we have come a long way since then. Hotter sharper spark, and more reliability with today's stuff. There is probably a reason nothing runs on points anymore.

[Stew Robertson]

Maybe a little hotter but when your electronic stuff craps out in a couple of years you can't get the file/ sand paper out and get her going and a set of point are cheaper than your electronics ( at least as long as Napa is around.

I hear you had a trip to Ontario, the bad lands where the little shi+ lives

[rob love]

Yes Stew, a quick in and out border raid, although with some collusion from your locals. Managed to get home in record time on your super salted highways, and am just getting everything put away today. Highest priority when I got home of course was to wash all the salt off everything.


As to the replacement of the electronic parts, with Amazon these days, you can order it online the minute you diagnose the problem, and the new parts can be at your door in 48 hours. NAPA does not do much better.