Stock coil with a Vintage Mallory distributor

[SkylarknMerc]

I just got a Mallory Distributor dual point, for my Mercury 255 flathead.

I'm getting parts together to convert to the 2g Rochester carb, and read that I need to get a mechanical advance distributor. I'm just not sure if the stock 12v coil would be enough to operate correctly.

Thank you.

[petehoovie]

Originally Posted by SkylarknMerc

I just got a Mallory Distributor dual point, for my Mercury 255 flathead.

I'm getting parts together to convert to the 2g Rochester carb, and read that I need to get a mechanical advance distributor. I'm just not sure if the stock 12v coil would be enough to operate correctly.

Thank you.

[tubman]

First of all, there is no "stock" 12 volt coil for a Mercury flathead; I presume you mean a standard 12 volt coil. The existing coil should work just fine with your new distributor. The distributor is just a high speed switch that excites the coil, so it's function will be no worse than with a stock distributor, and probably a little better because of the superior design of the Mallory unit.

One thing that you should take into consideration is whether or not you need a ballast resistor. Ideally, you want about 4 amps going through the points; anymore and they will burn and less will cause a weaker spark. Most 12 volt coils come in one of two varieties 1.5 ohms or 3 ohms resistance. With a 12 volt system, you can calculate which coil you need using Ohm's law, R=V/I (Resistance =Volts/Current (amps). In your case, you need 3 ohms totals resistance through the coil to achieve the desired current through the points (3=12/4). With a 1.5 Ohm coil you will need a 1.5 Ohm resistor.

In your case, I would be looking for a vintage Mallory coil to run. They look right and have proven to be quite robust. They sometimes even come with a bracket especially made for late model flatheads. I particularly like their "Best" coil.

[Bored&Stroked]

It is never a bad idea to have your "new" vintage distributor ran up on a distributor machine - making sure the bushings are good, the advance curve is correct, points are good, etc.. Might save you some drama down the road!

[SkylarknMerc]

Sorry , Yes standard 12v.
So unless its a Vintage Mallory distributor use a ballast resistor, just make sure to find out how many Ohms.

Thank you.

[SkylarknMerc]

Sponsored Links (Register now to hide all advertisements)

I thought about that, I just need to find someone local that is competent.

Thank you.

[tubman]

Originally Posted by SkylarknMerc

Sorry , Yes standard 12v.
So unless its a Vintage Mallory distributor use a ballast resistor, just make sure to find out how many Ohms.

Thank you.

No. The ballast resistor has nothing to do with the distributor. It has to match the coil .You want 3 Ohms totals resistance on a 12 volt system.

If you don't already have a Multi-Meter, get one and familiarize yourself with it's basic functions.

It's a valuable basic tool in your arsenal.

[hueyhoolihan]

Originally Posted by tubman

No. The ballast resistor has nothing to do with the distributor. It has to match the coil .You want 4 Ohms totals resistance on a 12 volt system.

If you don't already have a Multi-Meyer, get one and familiarize yourself with it's basic functions.

It's a valuable basic tool in your arsenal.

haha, you had me going there for a minute.... i thought maybe multi-meyer was possibly the german spelling for multi-meter or something, so i contacted Alexa and she said, no. the german spelling for meter was the same as that in English. ...and then i took a good look at my keyboard and noticed the "y" and "t" were next to one another.

[tubman]

Ooops, Fixed it (unless you're working on a VW).

[Kube]

Originally Posted by tubman

First of all, there is no "stock" 12 volt coil for a Mercury flathead; I presume you mean a standard 12 volt coil. The existing coil should work just fine with your new distributor. The distributor is just a high speed switch that excites the coil, so it's function will be no worse than with a stock distributor, and probably a little better because of the superior design of the Mallory unit.

One thing that you should take into consideration is whether or not you need a ballast resistor. Ideally, you want about 4 amps going through the points; anymore and they will burn and less will cause a weaker spark. Most 12 volt coils come in one of two varieties 1.5 ohms or 3 ohms resistance. With a 12 volt system, you can calculate which coil you need using Ohm's law, R=V/I (Resistance =Volts/Current (amps). In your case, you need 3 ohms totals resistance through the coil to achieve the desired current through the points (3=12/4). With a 1.5 Ohm coil you will need a 1.5 Ohm resistor.

In your case, I would be looking for a vintage Mallory coil to run. They look right and have proven to be quite robust. They sometimes even come with a bracket especially made for late model flatheads. I particularly like their "Best" coil.

I'm envious of your grasp of the electronics. I can do this stuff, but I struggle with it.

[SkylarknMerc]

Originally Posted by tubman

No. The ballast resistor has nothing to do with the distributor. It has to match the coil .You want 3 Ohms totals resistance on a 12 volt system.

If you don't already have a Multi-Meter, get one and familiarize yourself with it's basic functions.

It's a valuable basic tool in your arsenal.

Sorry I said that wrong. I understand, I need to use a Ballast resistor no matter wat with a 12v coil, and I need to run 3ohms resistance coil.

Thanks 😊

[tubman]

Again. with an ignition system, you want about 4 amps through the points and coil. On a 12 volt system with a 3 ohm coil, that means no resistor. With a 1.5 ohm coil (usually for 6 volts) you want a 1.5 ohm resistor (resistance in a circuit is cumulative when wired in series). Bottom line is that you need to know what the resistance of your coil is to decide what resistor is needed (if any)..

Ohms law R=V/I 3=12/4.

This is for conventional points systems; it goes out the window with electronic ignitions.

[SkylarknMerc]

Originally Posted by tubman

Again. with an ignition system, you want about 4 amps through the points and coil. On a 12 volt system with a 3 ohm coil, that means no resistor. With a 1.5 ohm coil (usually for 6 volts) you want a 1.5 ohm resistor (resistance in a circuit is cumulative when wired in series). Bottom line is that you need to know what the resistance of your coil is to decide what resistor is needed (if any)..

Ohms law R=V/I 3=12/4.

This is for conventional points systems; it goes out the window with electronic ignitions.

My man! Thank you.