My distributor is not putting out. So I am looking at other possible ways to get spark out of the parts I have on hand, spending as little money as possible. During my dive through the parts bin, I ran across a Mallory distributor pulled out of an old F motor. It has points, but no vacuum advance. I thought I might give it a try. I will be running it with a jacobs coil. How do I connect this thing? Anyone have one of these? I guess I will have to put in a ballast resistor, if I can't find my original one. What ohm rating is the original resistor? Is there a way I can get 12 volts to the coil and lower voltage to the points so as not to burn them, but get the best use of the high output jacobs coil?

You out there roundrocktom? This project still lurks.

thanks
tom

From what I can tell from the books, I need to get my black/yellow wire from the ignition to the + side of the coil, then run a wire from the - side of the coil to the terminal on the mallory dist. The points call for a resistor in line in from of the coil. I can't find in any of my 4 LC manuals if there is a resistor in my system, where it is or would be, and how many ohms it is. Does anyone know this?

From my understanding, the resistor has two purposes. One is to drop the voltage to protect the older coils. Two is to drop the voltage to protect the points or the ignitior. Sound right? If this is true, then why does it matter where the resistor is put? I have the Jacobs coil that will put out more juice if it gets 12 volts so I don't need to protect the coil. I do need to drop the voltage to protect the points, so can I put the resistor in the line from the - side of the coil to the points? It is just pulling to ground or not, right? So would it still work in that configuration, protecting the points yet giving the coil 12 volts?

Any thoughts would be a big help
thanks
tom

Morning Tom,

What happened with using the GM ignition Module? Did you ever get a chance to test out the pickup coil for an AC signal? I'd still be curious to what was or wasn't working before moving onto the next project.

Ballast Resistor: Typically a WHITE Ceramic item about 1/2" x 1/2" x 3" long. Lots of variations to it, but there are NOT fitted on some Toyota's as the igniter might be used to limit the amount of current to the coil, or on vehicles like GM's they used "resistance wire" (really an undersized wire) to drop the voltage.

Typically the ballast resistor will be from 1 to 5 ohms. Really depends on what the ignition coil requires in the way of voltage.

Whole idea is to limit the current to the coil & ignition points. Typically most engineers realized that if you drop the voltage in half (i.e. ov 12V, 6V across the ballast resistor 6V across the coil) that on really cold winter mornings the voltage at the battery will drop down to something like 6V, meaning only 3V across the coil. Not good. VIOLA: By pass the ballast resistor during the cranking so the coil sees the full 6V across it. Car starts easier.

The ballast resistor is usually sized to the ignition coil. On the older Accel Ignition coils, they always came with a ballast resistor. Kept things simple as you knew you had the correct ballast resistor. I know Summit will sell separate ballast resistors, but I haven't a clue as to what the Jacobs coil requires. I also did a quick search of Jacobs (http://www.jacobselectronics.com) to no avail. Search on "ballast" or "resistor" turned up zero matches. :mad:

Only thought is to call jacobs to see what they recommend for standard ignition points. I did call their customer service 1-800-825-3345 phone number. No luck in getting through (gave up after three tries).

Took a little searching on the Mr. Gasket web site to find an accel catalog, but at least a search of ballast resistors turned up a list of what ballast resistor to use with which coil. Odd thing was the ballast resistor was to be used in conjunction with the OEM one. Seems odd, but when you think of the GM using a "resistance" wire makes sense. Still the total ballast resistance should be matched to the coil.

Worse case, I would not feed more than 6 Amps through ignition points, 4 Amps being ideal. Assume a 13.6V system, typically you get about 13V at the "+" terminal of the coil after the wire and ignition switch. R= V/I resistance = voltage/current. We know current is 4 to 6 Amps, so total resistance needs to be from 2 to 3 Ohms (hey, I rounded this down in my head using 12V OK?)

Ballast Resistor recommendations:
Jacobs Ultra Coil is rated at 0.5 to 0.8 Ohms.
Add a 2 Ohm Ballast resistor

Jacobs Energy Coil is rated at 0.6 Ohm.
Add a 2 Ohm Ballast resistor.

Quick look on Summit Racing web site turned up a 1.82 Ohm Ballast resistor (Accel part number ACC-150150) for $10.39

Once again, best to check with Jacob's to see what they recommend with STOCK IGNITION POINTS.

Whew... hope this helps. Need to cut down on the Triple French Roast :D

Tom :usa:

Thanks for the extensive reply. I checked out everything I could with the gm module hooked up. Had a good module, good coil, etc. When I tested the pickup I was getting nothing. I tried reversing the leads, ac and dc, resistance was 150 ohms, but nothing. I adjusted the gap from .008 to wide open and everything in between, nothing. I don't get it. I am going to have it checked out by a local shop that only does electrical stuff, starters, alts, dist, etc.., and see what they say. In the mean time I am going to try to get this mallory working, never hurts to have a couple of options and I might be purchasing a 3rd project '69 FJ40 this weekend so all this work will end up having multiple applications.

I have been trying to get through to Jacobs for 2 months and their customer service line is always busy. They are moving from TX to NC and obviously feel customers can do without for a while. However, their sales line is open (go figure) and I talked to them yesterday. Taken with a grain of salt, I was told to use whatever resistance was recomended for the points. I was also told the coil would work perfectly well, if not better, getting the full 12 volts.

The only #'s I could get from the mallory web site was that they recommended adding their resistor if the vehicle was not equiped with one. Theirs is a variable resistor, .75 - 2.0 ohms, and is $14 from summit.

So this brings me back to my thought of a way to get the most bang out of what I have. If we assume the sales guy knows what he is talking about, we can give the coil full voltage without a resistor. Will things still work right if the resistor is placed after the coil, in the lead going from the - terminal on the coil to the distributor? If so, would it be better to buy a 2 ohm resistor or a wire resistor as with the gm and put it to the distibutor?

If this sound like damage waiting to happen or a design that just won't work, I'll go get a resistor and wire it in front of the coil. It would just be nice to get as much out of the coil as possible.

Thanks again for all the help and time put in with the searches and whatnot.
tom

Originally posted by trw
I have been trying to get through to Jacobs for 2 months and their customer service line is always busy. They are moving from TX to NC and obviously feel customers can do without for a while. However, their sales line is open (go figure) and I talked to them yesterday. Taken with a grain of salt, I was told to use whatever resistance was recomended for the points. I was also told the coil would work perfectly well, if not better, getting the full 12 volts.
tom

GASP!!!! Fawkers... good way to burn up the points! :mad3:

I would used a FIXED 2 Ohm resistor. The adjustable one has to have a "wiper" to adjust the resistance. With heat, moisture, dirt, and vibration it will act erract after time. Find something close to the 2 Ohm, and you should be good (i.e. the 1.82 Ohm is fine).

On the resistor: Doesn't really matter if it is mounted before of after the ignition coil, but to keep life simple & not mess with any mechanics looking at it:

Igntion power -------/\/\/\/\/-------- (+) coil coil (-) --------- pts.

Ya, put it in series with the power source and + coil. Just prevents someone on the trial from going "hey, your ballast resistor is hooked up wrong." :rainbow:

I need to modify my distributor test bench for the cruiser item.
Don't get all excited, but had a 0-5000 rpm DC motor (same as 0-10,000 rpm) with a holder for my Datsun distributor. With a simple O'Scope and vacuum pump I could recurve the distributor while sitting in a nice cool house. Nothing fancy, but was nice to be able to recurve things in August without sweat rolling into my eyes. :D

Tom :usa:

Thanks. I think for experimantal purposes (I'm a medical researcher and thus can't pass an opportunity to experiment) I'll try putting the resistor in both places (one at a time, not simultaneously) and test the performance and spark output. I'll start with it in front of the coil to make sure everything works first, then move it inbetween the - term and the dist. I'm not sure my VOM will read high enough to measure voltage at the plug. If it doesn't, is there something that can be used for this specific purpose?

Thanks yet again,
by the time this is over, my :beer: owed to you is going to be counted by pallets
tom