I need some help with an old Dodge truck.

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Run some various tests for spark. You may have a bad coil, points or condenser. DO NOT leave the ignition power to the coil for a long time

1...Points may not be closing. Bump engine, get points visually closed. Jump power to coil with voltmeter from coil points connection to ground. You should read very little voltage perhaps a volt or less. Full battery means the points are not closed.

If voltage is low, take a wire from coil tower to a plug etc for test gap. manually open points and let them snap closed and they should spark and you should get a spark from coil

2...Points may be opening but there may be a short. Missing/ broken points insulator, short where terminal/ wire goes through distributor wall AND OR bad condenser Bump engine so points are open, OR JUST manually open points with finger etc......measure points side of coil to ground. You should get full battery voltage. As before, except opposite, with points open and power to coil you should be able to short points connection to ground and re-open, and get spark from coil tower.
 
My thought was with the new coil and not using any of the truck wiring I need not use positive ground regardless of how the truck is wired?
 
I would----troubleshoot to get spark, shoot a bit of oil in cylinders, and crank with plugs out, then run a "quick" compression test. All cylinders if the battery is "hot" and if not just check maybe 3. If they are above 80 or better, it should at least try and fire. Cylinders may be dry, or been washed down with gas
 
Cope said:
My thought was with the new coil and not using any of the truck wiring I need not use positive ground regardless of how the truck is wired?
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Does not really matter. You can reverse coil leads but again, if 12V I would DIS connect the BAT connection at generator (if present) or NOT hook it to "system." In other words hook up only the coil and starter You don't want to burn up gauges, etc
 
I fully agree. The only wire from the truck being used is one connecting the distributer to the coil negative post.
 
j par said:
View attachment 1715824923View attachment 1715824927
This is a customers truck I think it's a 46..
It's a rare four-wheel drive...
Anyways he got it about 18 years ago and just after he got it he got an engine for it that he said he trickled a little gas and and heard it fire and run...
He had the brakes rebuilt at the axles but that was it. I showed him how to route the brake lines and told him to get a new master cylinder as his old one was very toast. It's 6 volt reverse polarity positive ground. And yes every one of these kind of worked on crank kind of slow... The battery reads 6.25... and they don't die easy... After he swore nobody ever touched the wires I finally figured out that all the wires were completely crossed..
I got it firing and running and got his brakes working for him..
The pictures depict the day we finally drove it for the first time since he owned it in near 20 years and actually got it running months before that...
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That is a 39 - 41
 
Neg ground good.
Test light, bat side of coil should always stay lit.
Dist side should blink with engine cranking and test light clip on bat side of coil and pointy bit on dist side of coil.
Another easy thing to do is check for an arc at points either bridging with a screwdriver or opening them if they are closed.
Breaker plate moves, the wires in there can break or short.
 
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67Dart273 said:
Run some various tests for spark. You may have a bad coil, points or condenser. DO NOT leave the ignition power to the coil for a long time

1...Points may not be closing. Bump engine, get points visually closed. Jump power to coil with voltmeter from coil points connection to ground. You should read very little voltage perhaps a volt or less. Full battery means the points are not closed.

If voltage is low, take a wire from coil tower to a plug etc for test gap. manually open points and let them snap closed and they should spark and you should get a spark from coil

2...Points may be opening but there may be a short. Missing/ broken points insulator, short where terminal/ wire goes through distributor wall AND OR bad condenser Bump engine so points are open, OR JUST manually open points with finger etc......measure points side of coil to ground. You should get full battery voltage. As before, except opposite, with points open and power to coil you should be able to short points connection to ground and re-open, and get spark from coil tower.
Click to expand...


Neg ground good.
Test light, bat side of coil should always stay lit.
Dist side should blink with engine cranking and test light clip on bat side of coil and pointy bit on dist side of coil.




Thank you.

I will do this after the holliday.
 
Cope said:
Neg ground good.
Test light, bat side of coil should always stay lit.
Dist side should blink with engine cranking and test light clip on bat side of coil and pointy bit on dist side of coil.




Thank you.

I will do this after the holliday.
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Rocker pat did a video to help a guy with troubleshooting point ignition. Its the only one i know of at the moment.
 
6v to 12v is easy, done this on my Willys, going to do the same thing on my 46 dodge truck.
Gauges, light bulbs will not work you will fry them, they do make a resistor for the gauges.
Points, condenser will work with 12V, just use a mopar 71 style ballast resistor with the proper coil external resistance coil.
Starter, had a local rebuilder go thru it, running 12V is basically a non-issue as long as the engine starts easy.
I used a ford starter relay, to use a key start, easier than pushing the foot button.
About all old cars are the same.
 
Also run the valves on the old flat head, I but you find some that are stuck, or not seating.
A dead cylinder or two will kill your chances of the low-compression engine starting.
 
I Love that Body style.
 
Here's what she looks like from the rear.

20211124_113136.jpg


Yes pleas. I want that.
 
sireland67 said:
That is a 39 - 41
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Actually I think it might be a 41 and that's why we're thinking it was part of the building of the Alaskan highway...
I guess I just got mixed up cuz I've worked on quite a number of 46 willys Jeeps...
 
j par said:
Actually I think it might be a 41 and that's why we're thinking it was part of the building of the Alaskan highway...
I guess I just got mixed up cuz I've worked on quite a number of 46 willys Jeeps...
Click to expand...
Pre war trucks have the headlights closer to the hood, post war trucks have the headlights on the centerline of the fenders.
Here is a picture of my 46.

wLuiM9.jpg
 
sireland67 said:
Pre war trucks have the headlights closer to the hood, post war trucks have the headlights on the centerline of the fenders.
Here is a picture of my 46.

View attachment 1715825908
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After helping people work on their nostalgic trucks and cars for 8 to 10 years now I'm starting to lose track of which one was which year LOL some of these older ones still have the provision for crank starting it. I know the 29 Ford I worked on did.. I want to say this truck had a provision for it as well...
It may even be a 39 with a 41 motor or something like that I'm not sure..
 
j par said:
After helping people work on their nostalgic trucks and cars for 8 to 10 years now I'm starting to lose track of which one was which year LOL some of these older ones still have the provision for crank starting it. I know the 29 Ford I worked on did.. I want to say this truck had a provision for it as well...
It may even be a 39 with a 41 motor or something like that I'm not sure..
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I have a book with numbers on old dodge trucks, give the the numbers off the engine, I can verify what it is.
 
sireland67 said:
I have a book with numbers on old dodge trucks, give the the numbers off the engine, I can verify what it is.
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The guy that owns the truck lives about an hour and a half away and calls me about once every 4 to 6 months over the last year and a half to two years to come help him work on his truck.. the next time I'm there I'll get more information and more pictures...
 
j par said:
The guy that owns the truck lives about an hour and a half away and calls me about once every 4 to 6 months over the last year and a half to two years to come help him work on his truck.. the next time I'm there I'll get more information and more pictures...
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Sounds good, The book also can identify vin numbers.
 
Cope said:
I fully agree. The only wire from the truck being used is one connecting the distributer to the coil negative post.
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Without reading back through everything what was it you were going to gain by turning this into 12 volt?..
 
If 12 volts were absolutely necessary somewhere it would seem like a 12 volt alternator could be tethered in as well as a 12 volt battery to run whatever needs 12 volts? A stereo?...
 
Cope said:
Bob at Hot Rod Wires says I need a new 12V condenser. It looks like I can just use one out of the old 1971 Dart parts?

Can I just use a standard 1970s points condensor?

He also mentioned I need ignition balest resistor.

If we are rewiring this entire truck AND changing the voltage why do we need that stupid resistor?

What dose that thing do again? (All our cars run MSD units now.)

Thanks again for your advice.
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You can still use the origional distributor just need a different condenser. Hey after the dist number should be a numeric=alpha numre IE 2U That will give me a code to look up on dating the distributor.
 
Allright let's get down to business on ignition capacitors, back then called "condensers."

VOLTAGE RATING. All capacitors have a voltage rating but that is not generally published for ignition caps because they all see ??up to?? 200V or so peak. They are rated, it's just that the ratiing is not published. So voltage rating for caps between 6 or 12V systems is not relevant.

CAPACITANCE. here are a few random figures.
================================================================
First are from 67 Dodge manual, so "typical" 12V 60's ratings
Capacitance for 6 cyl, 273V8, 318, 383, 440, and 426 hemi, are all shown as .25-.285 mfd (microfarad)
================================================================

Next from 1960 Plymouth service manual

1960 225 6 is ............ .25--.285mfd
V8 318 and 361 ......... .25--.285mfd
=================================================================

Last from an old, tattered, "Motor's" manual, 16th edition, copyright 1953

Under Dodge, the chart all the way from 1936--to 1953 V8 says............... .25---.28 mfd
===================================================================

The cap value depends on the COIL, not the system voltage. Some systems such as Mallory may have used other cap values, and "back in the day" you could BUY different values of caps if breaker points showed pitting on one side or the other---I don't recall-------pitting on ground side you went one direction, pitting on "hot" side, you went the other, etc.

==================================================================

Frazier, 47--48 shows .20--.25mfd
Henry J shows .21--.25mfd
Hudson/ Terraplane shows .20--.25mfd
Desoto same as Dodge
Some Nash shows .18--.25, some shows .20--.25 AND I CAN TELL YOU that is "not" much difference...
Poncho shows .18--.23mfd
Ford all the way from '36 to 48 shows .21--.25mfd
===================================================================

IS A PATTERN STARTING TO FORM HERE???

The correct answer is, "it probably won't make much difference" IF IF the one you use is in good operating condition. Remember that ...........

"New" does not mean "good"
And you CAN NOT check a condenser with an ohmeter
And you CAN NOT check a condenser with a modern solid state cap checker

WHY?

Because almost NO testers check for HIGH VOLTAGE LEAKAGE

The ONLY instruments I have that check for high voltage leakage is the old Bruno tester I have, and an old Heathkit, as well as two (need to be restored) Eico testers These testers in reality are only good for one thing...........LEAKAGE tests. ..........HIGH VOLTAGE leakage tests. The capacitance readings are "accurate enough" but the modern pocket cap checkers are more accurate "for capaciatance"

This is a photo (off the internet) of the same model as my old heathkit. This is so old it uses "octal" vacuum tubes---the ones with the big 8 pin base and "key" in the middle

c3-450.jpg


A stolen photo of the Eico, in many ways similiar to the Heathkit

EICO950BBridgeOperating.jpg


This is my Bruno tester, and I use the crap out of it on outboards. It tests caps for leakage and value, and tests coils for comparative output voltage

Notice the "leakage" scale is just a "go / no go" deal and right above in red is the capacitance...just reads right out. Outboards run around .22mfd
The next scale up in black says "KV".......That's RIGHT that is KILO volts, for coil output

The ohms scales are good for checking coil continuity which is a joke because if they were open they would not work, and if they are "partially shorted" the meter is not accurate enough.........Neither are modern digi ohmeters....... But it IS useful for "points resistance"

coils-l1600cs-jpg.jpg


3s-l1600cs-jpg.jpg
 
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WHAT DOES THIS MEAN? It means just about any cap you can buy for a breaker points automotive ignition, that will bolt into the distributor will work. Some lower, and some higher, may make "a bit" less or more spark, and some lower, or higher in value might pit the points "somewhat" quicker or slower.

The IMPORTANT thing is that the cap is in good working condition. Not leaky, open, shorted, or so old it is "dried out", or full of water.

The best way to check? Hook "system" ---the dist, the coil, and battery up and see if it sparks, making sure points actually close and draw current, and when open, are really "open."
 
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