proper coil/distributor combination for '39

40cpe

40cpe

Well-known member
A friend is helping a friend with his '39 deluxe 85 HP that is hard to start when warm. What is the proper ballast, coil, distributor combination for that year? should it have the ballast under the dash on the firewall with the coil mounted on the distributor?
 
If it has the original distributor, it would be a "Helmet" type with the coil mounted on top with 2 screws. The condenser is also mounted with the distributor. The ballast resistor is under the dash.
For reliability, I would have the coil redone by Skip Haney in Florida, and maybe get a new condenser. The ballast seldom causes any problem
 
Here is the wiring diagram if that help you any. The original coil was mounded on the distributer. There was a resister unit mounted under the dash.

The resistor assy is 18 12250 and used 32-48.
 

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Yes, '39 would have a resistor on the firewall behind the dash, '37-'41 helmet type distributor with a two screw mounted coil on top of the distributor. The distributors in those years would have used some different advance weights. Not sure what advance curve would be stock for '39, but the '41 advance curve may have been considered to be the best.
 
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Thank you 40cpe for posting the question and thanks for the responses. As mentioned above, I'm working on my friend's 39 Deluxe, he wants it rewired staying with the 6v system. The problem he is having in addition to the headlights barely working is that once driven, the engine will not start while hot. You have to let it cool off before it will generate spark. Someone in the past took off the original coil because there isn't one on the distributor anymore; it's been replaced by a cylindrical coil which has been mounted between the carb and fuel pump.
 
Hivolt5.0 said:
Thank you 40cpe for posting the question and thanks for the responses. As mentioned above, I'm working on my friend's 39 Deluxe, he wants it rewired staying with the 6v system. The problem he is having in addition to the headlights barely working is that once driven, the engine will not start while hot. You have to let it cool off before it will generate spark. Someone in the past took off the original coil because there isn't one on the distributor anymore; it's been replaced by a cylindrical coil which has been mounted between the carb and fuel pump.
Click to expand...

If it is a spark issue with heat soak it could well be the coil or the condenser.
 
JSeery said:
If it is a spark issue with heat soak it could well be the coil or the condenser.
Click to expand...

There is a condenser on top of the distributor that I assume is supposed to be there?? How would I check to determine if the coil or condenser is bad when hot?
 
Hivolt5.0 said:
Thank you 40cpe for posting the question and thanks for the responses. As mentioned above, I'm working on my friend's 39 Deluxe, he wants it rewired staying with the 6v system. The problem he is having in addition to the headlights barely working is that once driven, the engine will not start while hot. You have to let it cool off before it will generate spark. Someone in the past took off the original coil because there isn't one on the distributor anymore; it's been replaced by a cylindrical coil which has been mounted between the carb and fuel pump.
Click to expand...
I would probably rewire the car first, then see where you're at with the starting problem. Could be related.
 
Does anyone know the resistance of the stock coil on a '39?

And what should the voltage be at the coil with the resistor warm and points closed?
 
40cpe said:
Does anyone know the resistance of the stock coil on a '39?

And what should the voltage be at the coil with the resistor warm and points closed?
Click to expand...

The stock 6 volt coil is .6-.8 ohms primary resisitance........on the average car you will see 3.5 volts or more at the coil ......

Assuming the resistances are the same (close to equal) each would drop the voltage 3 volts with engine not running . A running engine will supply a 7-7.2 volt feed and then they would drop 3.6 volts etc......
Pretty amazing that the coil can and does produce spark at 3 volts supply but they do very well ......
assuming everything else in the circuit is perfect....
 
I ohmed the coil and resistor last night, both of them cold. The coil measured 1.6-1.7 ohms of resistance between the posts and the resistor under the dash measured .5 ohms. I did notice that one of the terminal nuts on the resistor was loose so I tightened it. It was late at night so I didn't drive the car in order to test the ohms of the coil and resistor when hot.

Also, here are a couple of pics of the distributor and coil. I'm new to flatheads so please forgive my ignorance.

picture.php


picture.php
 
40,
Is it possible the tube coil has an internal resistor in it ? Usually somewhere
on the body of the coil there is a note stating this.
Charlie ny
 
Hivolt5.0 said:
I ohmed the coil and resistor last night, both of them cold. The coil measured 1.6-1.7 ohms of resistance between the posts and the resistor under the dash measured .5 ohms. I did notice that one of the terminal nuts on the resistor was loose so I tightened it. It was late at night so I didn't drive the car in order to test the ohms of the coil and resistor when hot.

Also, here are a couple of pics of the distributor and coil. I'm new to flatheads so please forgive my ignorance.

picture.php


picture.php
Click to expand...

Coil is incorrect for the 6 volt system.....................
 
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