Not using an ignition resistor on my 48 mercury

[[email protected]]

Hi Ford Barn Folks,

My 48 Mercury is still 6 volt pos. ground. It has the original dual point distributor. Before I got it, someone had removed the ignition resistor behind the gauges. So I am always getting a full 6 volts to the distributor. Will this burn out the points quickly? Should I install a resistor? Is there a 6 volt coil on the market that I could run without adding a resistor.

Thanks for any advice!

Bill in Connecticut

[flathead48]

I believe the later round coils have resister built in. Napa should have one,, yes 6 volts will burn your points

[flathead48]

Are you using the original one Ford coil or round can, check the voltage coming out of your coil if you are around 4 volts than there is a resister in play

[koates]

Well it is difficult to answer any questions here because you did not mention which coil you have on your car and what is the coil primary winding resistance in ohms ? If you have the original bakelite FORD coil then you need the original FORD ballast resistor. You dont measure the volts at the distributor but measure the volts at the coil ignition feed terminal. An original coil should run on about four volts through the ballast resistor. The real test is to measure the current in amps that a coil is drawing with the ignition ON and points closed (about 4 amps) and then with engine running at idle (about 2 amps) More info needed. Regards, Kevin.

[[email protected]]

Thanks. Should have mentioned which coil I am using. It is a 6 volt round coil from a 51 Ford. 6 volt. I will check the voltages as mentioned in your posts.
Thanks!

Bill

[Jack E/NJ]

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The voltage on the round coil's points side should be 0v with points closed, And full 6v with points open whether a resistor's in the circuit or not. If there's an external resistor in the circuit, the voltage on the round coil's ignition side should be significantly less than 6v with the points closed. Jack E/NJ

[JSeery]

Originally Posted by [email protected]

Thanks. Should have mentioned which coil I am using. It is a 6 volt round coil from a 51 Ford. 6 volt. I will check the voltages as mentioned in your posts.
Thanks!

Bill

That coil does not require a ballast resistor, you should be fine the way it is.

[Kurt in NJ]

I think by 48 it was moved out to the top of the coil

[JSeery]

Originally Posted by Kurt in NJ

I think by 48 it was moved out to the top of the coil

But, not needed if it's a can coil.

[[email protected]]

Thanks for all of the great input. Checked voltage during cranking this morning and it was 3.5 when the points are closed. I do have a 6 volt "can" coil on the car. I looked on the back side and it does say no external resistor required, just as Kurt said.

I have noticed that the engine was cranking over slower than it used to. I swapped batteries form another 6 volt car and the Mercury cranks faster and starts much quicker. I think my old battery was weak and the voltage dropped so low that I sometimes lost adequate voltage to the distributor making it difficult to start. I'm in good shape now. Thanks!
Bill

[40 Deluxe]

Originally Posted by [email protected]

Thanks for all of the great input. Checked voltage during cranking this morning and it was 3.5 when the points are closed. I do have a 6 volt "can" coil on the car. I looked on the back side and it does say no external resistor required, just as Kurt said.

I have noticed that the engine was cranking over slower than it used to. I swapped batteries form another 6 volt car and the Mercury cranks faster and starts much quicker. I think my old battery was weak and the voltage dropped so low that I sometimes lost adequate voltage to the distributor making it difficult to start. I'm in good shape now. Thanks!
Bill

Check your charging system voltage before condemning the battery. Maybe that battery just never got fully charged. Should be about 7.2 volts at the battery terminals with the engine running about 1500.

[Aarongriffey]

Some new round coils need external resisters and some have a resister buil in.
I have see thirties and forties cars running without a resister or bypassed.
It shortens the life of the points though.

[backrodebob]

If you find you need one Napa Echlin IC7

[backrodebob]

that didn’t sound right, this coil has internal resistor

[[email protected]]

Thanks.

Will check my charging rate, also.

Bill

[JSeery]

Originally Posted by Aarongriffey

Some new round coils need external resisters and some have a resister buil in.
I have see thirties and forties cars running without a resister or bypassed.
It shortens the life of the points though.

Sorry, this is not correct information. The resistance of a coil is determined by the number of windings and the material it is constructed from. I'm sure you can find a coil built for some application that has the wrong resistance for a 6v system. But 6v volt coil (~1.5 ohms) do not use a ballast resistor and the ignition system is designed to work with this combination (we are talking "can" coils here, not the original OEM style of coils). In a 12v volt system, you can use the same coil coupled with a ballast resistor (~1.5 ohm coil + ~1.5 ohm resistor = ~3.0 ohms) OR a coil with a ~3.0 ohm coil without a ballast resistor. But on the 6v system use a 1.5 ohm coil no ballast resistor is use and putting with in the circuit can interduce problems.

[[email protected]]

Really good, interesting and informative information. I've sure learned a lot about coils in the last few days!
Thanks again.
Bill