and it begins, electrical ???'s

[realgonekatt]

Hey yall, This week I decided to bite the bullet and start building a new wiring harness from scratch, as I just rebuilt the genny, and picked up a rather large tractor battery from napa as well as a new regulator. So far all I have wired is the basic stuff to run i.e. ignition switch, coil, starter button, generator and regulator. I followed a wiring diagram from a 47 dodge p/u shop manual, and referenced a p-15 diagram on this forum. Which brings me to the problem at hand. I tried to start her and she turns over (slow) but has no spark. So I jumped power to the coil via batt. and now shes sparkin' (so far I flooded the piss outta her and am giving her/me a brake for a few beers or so) Now, Is it possible that my issue could be that the "other" side of the ammeter is hooked to nothing? It looks like it only goes to the horn relay anyhow, which means it would still be open most of the time?? or maybe the fact that it hasnt really run

yet means the regulator isnt feeding enough to the ammeter? (I made sure to polarize the gen). But, the starter solenoid works which runs off the fuel gauge which pigtails off the ignition switch. She ran great last week off an old 12v batt (charging system disconected) till I let all the smoke outta the wires:rolleyes:

[Young Ed]

Which are you working on a p15 or a 47 pickup or what? Some big differences between the truck and the car

[Plymouthy Adams]

Ed..judging by his profile shot..saying P15

[Young Ed]

I saw that. Not sure why he's following the truck wiring diagram then. Granted most of it transfers but trucks don't use solenoids or horn relays

[steveplym]

Hey yall, This week I decided to bite the bullet and start building a new wiring harness from scratch, as I just rebuilt the genny, and picked up a rather large tractor battery from napa as well as a new regulator. So far all I have wired is the basic stuff to run i.e. ignition switch, coil, starter button, generator and regulator. I followed a wiring diagram from a 47 dodge p/u shop manual, and referenced a p-15 diagram on this forum. Which brings me to the problem at hand. I tried to start her and she turns over (slow) but has no spark. So I jumped power to the coil via batt. and now shes sparkin' (so far I flooded the piss outta her and am giving her/me a brake for a few beers or so) Now, Is it possible that my issue could be that the "other" side of the ammeter is hooked to nothing? It looks like it only goes to the horn relay anyhow, which means it would still be open most of the time?? or maybe the fact that it hasnt really run

yet means the regulator isnt feeding enough to the ammeter? (I made sure to polarize the gen). But, the starter solenoid works which runs off the fuel gauge which pigtails off the ignition switch. She ran great last week off an old 12v batt (charging system disconected) till I let all the smoke outta the wires:rolleyes:

Hello and welcome to the forum. So you are running 6v then correct? Make sure you have your battery with negative post to positive and positive post to ground, as this is a positive ground system. You will need wires coming out both sides of the ammeter. One side goes to the big terminal on the solenoid that goes out to the battery. The other side goes to the ignition switch, the bat terminal on the regulator, and to the headlamp switch.

From the ignition switch it powers up the flasher, out to the negative terminal on the coil as it is positive ground. Think all negative is positive and positive is negative. Like a three stooges reel I saw once.

Also goes from the iginition switch to the flasher if you have turn signals and to the fuel gauge.

With 6 volt you will also need very large battery cables. 00 is recommended as the wires required for 6 volt need to be larger. Almost all my car is wired with 10, 12, and 14 gauge wiring.

I went ahead and linked the p-15 wiring diagram here to explain. I replaced my harness one wire at a time by following the diagram. Worked very well and go rid of that old rat nest of wires. Another thing I just thought about with your comment about the ammeter being connected to the horn relay. That wire on that leg of the diagram does not run right to the horn relay. The relay and that wire to the ammeter connect to the terminal going to the battery on the solenoid. In the picture below you can see the connection.

[realgonekatt]

Sorry about the vagueness of that post, I was a little flustered trying to get ****

done on my day off....The vehicle in question is in fact a 46 plymouth c. coupe.

I was using the dodge diagram as I happened to have that shop manual left from a previous project. Most of the engine electrical is similar. And it lists all the proper gauge #'s

This evening I bought a 6v charger and it appears that the battery was pretty low (still charging)

Thanks for the info about the ammeter steve, It was a little hard to distinguish that connection in the diagram, anyhow, after running a 10awg from the ammeter to the solenoid I have spark without jumping the coil to the batt:)

Im familiar with positive ground systems as I made the harness for my 66 bsa motorbike, 6v however, is a whole new thing to me, I just figured that with half the volts everything is likely running twice the current and therefore double the wire size?

In retrospect I wish id more thoroughly documented where everything was connected But, half the wires were bare and colors were completely indistinguishable...

[steveplym]

You are correct about the wire size. If you get a service manual and go up to the 1949 diagram it will tell you the wire gauge on each circuit. It helps as you can compare that to the P-15 and used that gauge wire. Like I said on most circuits where I knew there would be high current such as the batt wire to the regulator, wires to the generator, etc, etc. I used 10, then used 12 on most everything else, used some 14 on some less heavy duty circuits. Didn't use much that was less than 14.

[realgonekatt]

Just went out and fired her up!!!! Looks like the low batt. was the culprit (combined with the ammeter deal) She idled for about 20 minutes no problem.

Although apparently in my infinite wisdom I hooked up the ammeter backwards. So next up is the lights, I currently have no turnsignal switch or

dual filiment bulb holders. anyone know where to pick some up on the budget??

I noticed alot of smoke out of the oil fill hole, I supose that is from the lack of a

real pcv system. Pretty normal??? thinking of riggin up some sorta pcv setup..

[Don Coatney]

I noticed alot of smoke out of the oil fill hole, I supose that is from the lack of a

real pcv system. Pretty normal??? thinking of riggin up some sorta pcv setup..

A healthy engine will have very little smoke out of the oil fill tube (AKA blow-by). A PCV system will not repair broken or worn piston rings. Have you done a compression check?

[realgonekatt]

Damn, thats exactly what my pops said, I dont wanna hear that:rolleyes:

Im actually gonna do a compression check today, gotta grab my gauge from the shop (seems like the tool I need is always at the shop)

I was hoping this mill will hold up until I can build my spare dodge flathead.

Although a set of rings on one of these old dogs seems like a fairly simple affair, Ive got alot of other things to "get tied up"

[greg g]

just a caveat, even though Don's observation is basically correct. Prolonged idling will make the situation appear a bit worse than it may be. the road draft tube located at the rear passenger side of the engine is the exit of the system. However it only really works when the car is in motion. The balogna angle cut on the pipe creates a lowpressure area at the end of the pipe which is meant to draw crankcase vapors out. But it depends on the cars forward motion to do so. The result is that at idle or with the engine off after running the heated air will rise and carry fumes and smoke out of the oil fill tube like a chimney draws hot smoke out of a stove.

When you do your comp check keep in mind there were pretty low compression motors. 120 psi was factory spec. So if you are in the 80's or above you are probably good for a few thousand miles. The key is readings within + or - 10% across the cylinders. Folks have reported engines putting out only 75 lbs per cylinder will run and drive very well thank you. May not be as perky or pull hills well but should give you plenty of time to refresh your spare engine.