The Ford Barn

dorvedahl47pu · 03-22-2025, 11:29 AM

Greetings,

I've got a number of 1940-1947 pickups and big trucks. Two of them are "1947 Late" configured in that the cowl wiring harness is different than the typical 40-47 configuration. The only functional difference I have noticed is that the 47 Late configuration does not have the firewall mounted CB and ignition resistor panel. The CB panel in the late configuration is mounted to the instrument panel but there is no ignition resistor.

Given that fact, how is the ignition circuit different? Is there then no voltage drop required in the ignition circuit? Are there changes elsewhere that might account for there not being a resistor? Does the coil need to be a different type/style, different condensor, etc.?

Basically, I'm looking for something that explains how the ignition system works in the 47-late verses the typical 40-47 configuration.

Thanks in advance.

Dale

fordyford · 03-23-2025, 06:21 AM

I have had some coils with a resistor mounted directly on them. It had a small fiber back plate that included a terminal to attach the feed wire.

1942deluxe · 03-23-2025, 08:06 AM

What fordyford said. The CB has the normal B, A, H terminals going left to right. The coil wire goes to the resistor mounted on the coil on a short fiber board. From the factory they did indeed use the resistor.

dorvedahl47pu · 03-24-2025, 10:01 AM

Thank you, Gentlemen. Would a modern can type coil with an internal resistor do the trick as well?

1942deluxe · 03-24-2025, 10:18 AM

Yes, I'm running a NAPA IC7 coil on my 48 and haven't had problems. Has the internal resistor. My 42 and 46 have the stock CB and resistor set up.

Drbrown · 03-24-2025, 11:38 AM

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Yes one with an internal resistor would be okay but be sure to remove the stock resistor. I use a Blue Flame coil with stock points distributor.

dorvedahl47pu · 03-24-2025, 11:49 AM

Copy, thanks!

dorvedahl47pu · 03-24-2025, 11:50 AM

Thank you, Sir.

dorvedahl47pu · 03-24-2025, 11:52 AM

Quick follow-on question. What are some possible reasons that the truck not fire/start using the starter but fire right up on a pull start/popping the clutch in gear start?

03-22-2025, 11:29 AM	#1
dorvedahl47pu Member Join Date: Sep 2020 Location: Hooper, Utah Posts: 97	1947 vs 1947-Late Models Greetings, I've got a number of 1940-1947 pickups and big trucks. Two of them are "1947 Late" configured in that the cowl wiring harness is different than the typical 40-47 configuration. The only functional difference I have noticed is that the 47 Late configuration does not have the firewall mounted CB and ignition resistor panel. The CB panel in the late configuration is mounted to the instrument panel but there is no ignition resistor. Given that fact, how is the ignition circuit different? Is there then no voltage drop required in the ignition circuit? Are there changes elsewhere that might account for there not being a resistor? Does the coil need to be a different type/style, different condensor, etc.? Basically, I'm looking for something that explains how the ignition system works in the 47-late verses the typical 40-47 configuration. Thanks in advance. Dale

03-23-2025, 06:21 AM	#2
fordyford Senior Member Join Date: May 2010 Posts: 265	Re: 1947 vs 1947-Late Models I have had some coils with a resistor mounted directly on them. It had a small fiber back plate that included a terminal to attach the feed wire.

03-23-2025, 08:06 AM	#3
1942deluxe Senior Member Join Date: Jan 2011 Location: Albion, PA Posts: 986	Re: 1947 vs 1947-Late Models What fordyford said. The CB has the normal B, A, H terminals going left to right. The coil wire goes to the resistor mounted on the coil on a short fiber board. From the factory they did indeed use the resistor.

03-24-2025, 10:01 AM	#4
dorvedahl47pu Member Join Date: Sep 2020 Location: Hooper, Utah Posts: 97	Re: 1947 vs 1947-Late Models Thank you, Gentlemen. Would a modern can type coil with an internal resistor do the trick as well?

03-24-2025, 10:18 AM	#5
1942deluxe Senior Member Join Date: Jan 2011 Location: Albion, PA Posts: 986	Re: 1947 vs 1947-Late Models Yes, I'm running a NAPA IC7 coil on my 48 and haven't had problems. Has the internal resistor. My 42 and 46 have the stock CB and resistor set up.

03-24-2025, 11:38 AM	#6
Drbrown Senior Member Join Date: Oct 2013 Location: Glens Falls NY Posts: 1,355	Re: 1947 vs 1947-Late Models Sponsored Links (Register now to hide all advertisements) Yes one with an internal resistor would be okay but be sure to remove the stock resistor. I use a Blue Flame coil with stock points distributor.

03-24-2025, 11:49 AM	#7
dorvedahl47pu Member Join Date: Sep 2020 Location: Hooper, Utah Posts: 97	Re: 1947 vs 1947-Late Models Copy, thanks!

03-24-2025, 11:50 AM	#8
dorvedahl47pu Member Join Date: Sep 2020 Location: Hooper, Utah Posts: 97	Re: 1947 vs 1947-Late Models Thank you, Sir.

03-24-2025, 11:52 AM	#9
dorvedahl47pu Member Join Date: Sep 2020 Location: Hooper, Utah Posts: 97	Re: 1947 vs 1947-Late Models Quick follow-on question. What are some possible reasons that the truck not fire/start using the starter but fire right up on a pull start/popping the clutch in gear start?