The Ford Barn

glennpm · 10-02-2016, 09:51 AM

Hi,

I have one of Bubba's converted crab style distributors on a 59A V8. It is a negative 12 volt ground. Ignition coil resistance measures at 2.6 ohms and has no external resistor.

The 32 is not ready to run yet and am working on the wiring. With the ignition on, I'm getting negative 7-8 amps on my 32 ammeter. Is this a "normal" within range value?

Ross F-1 · 10-02-2016, 10:54 AM

Sounds high, but I wouldn't trust a dash gauge to be accurate.

Drbrown · 10-02-2016, 11:05 AM

Check with Bubba, he can best respond .... Russ F-1 right - take a reading at the coil + side with a good test meter. Would amp reading be accurate without engine running ? That internal resistance might be a bit high at 2.8 ? I have two coils, one from Bubba, and each read 1.8 last week. (granted 1.5 or above normal for 12v V8).

Dec211975 · 10-02-2016, 01:30 PM

Calculating the amperage with the numbers provided (12 volts, 2.6 ohms) the amperage should be 4.615

glennpm · 10-02-2016, 02:11 PM

Thanks Guys and Dec211975, I should have checked with Ohms Law like you did. I'm going to recheck my resistance and also see what Bubba may say.

Thanks!

Okay I remeasured and got about 2.3 ohms resistance so ammeter should be about 5 amps considering I measured about 11.7 volts at the ignition switch this morning.

JSeery · 10-02-2016, 03:21 PM

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You really need a ballast resistor with that coil value. You are looking for ~3.5 to 4 amps max and if you use the more realistic higher voltage numbers it will be about 4 amps. a charged battery with the engine not running should be around 12.6 to 12.7 volts and with the generator charging the battery it could in in the 14.7 or so range.

12.6V / 2.3 ohms = 5.5A & 14.6V / 2.3 ohms = 6.4A This is way to high and you need a ballast resistor in the circuit, it needs to be sized for the engine running current.

Step-down · 10-02-2016, 04:21 PM

When testing make sure your points are in the open position ..... To evaluate there isn't any other issue your dealing with first ....

glennpm · 10-02-2016, 04:33 PM

Hi Jserry,

Yes, I thought the amperage was too high too. Bubba's FAQ said to just make sure for a V8 that the resistance is greater than 1.5 ohms so I thought I was good until I noticed the high draw this morning on my 1932 dash ammeter. I'll put a ballast resistor in.

Thanks

JSeery · 10-02-2016, 06:08 PM

1.5 would be for like a 6v system OR a 1.5 ohm coil and a 1.5 ohm ballast resistor for a total of 3.0 ohms in the circuit on a 12v system. Without a ballast resistor the coil needs to be in the 3 to 4 ohm range.

BUBBAS IGNITION · 10-02-2016, 07:00 PM

Quote:

Originally Posted by glennpm

Hi,

I have one of Bubba's converted crab style distributors on a 59A V8. It is a negative 12 volt ground. Ignition coil resistance measures at 2.6 ohms and has no external resistor.

The 32 is not ready to run yet and am working on the wiring. With the ignition on, I'm getting negative 7-8 amps on my 32 ammeter. Is this a "normal" within range value?

Is this electronic conversion or points.???????If electronic the coil that came with the conversion is to be used with the electronic module and shouldnt be tested without the engine running. The module regulates the current with circuits and is a "time " control as well...

If its points then the amps.... is a little ( double _)
high ???

Drbrown · 10-02-2016, 11:12 PM

glennpm .... following-up our pm exchange .... you have a Pentronix module in crab. The coil furnished with that should have internal resistor.

Just communicated with Bubba's. The coil he sold me with my Pentronix was reading 1.8 ohms and he will confirm what a proper reading should be. That should answer your issue about ohm reading for your coil and indicate what amperage your module and coil would be expected to be drawing.

As noted, friday a Pentronix Company Tech advised me their modules are designed to require a minimum of 9 volts and tolerate a maximum of 16 volts. They have been know to survive momentary voltage spikes in excess of 16 (I can attest to that). They are warranted for 30 months from sale for workmanship.

JSeery · 10-03-2016, 06:24 AM

Well, I missed the "converted" in the OP! Little things make a difference!!!!!

10-02-2016, 09:51 AM	#1
glennpm Senior Member Join Date: Sep 2014 Location: Wiscasset, Maine Posts: 1,981	Amperage Draw with Ignition on? - Bubba Ignition Question Hi, I have one of Bubba's converted crab style distributors on a 59A V8. It is a negative 12 volt ground. Ignition coil resistance measures at 2.6 ohms and has no external resistor. The 32 is not ready to run yet and am working on the wiring. With the ignition on, I'm getting negative 7-8 amps on my 32 ammeter. Is this a "normal" within range value?

10-02-2016, 10:54 AM	#2
Ross F-1 Senior Member Join Date: Nov 2010 Location: NM Posts: 2,438	Re: Amperage Draw with Ignition on? - Bubba Ignition Question Sounds high, but I wouldn't trust a dash gauge to be accurate. __________________ '52 F-1, EAB flathead

10-02-2016, 11:05 AM	#3
Drbrown Senior Member Join Date: Oct 2013 Location: Glens Falls NY Posts: 1,267	Re: Amperage Draw with Ignition on? - Bubba Ignition Question Check with Bubba, he can best respond .... Russ F-1 right - take a reading at the coil + side with a good test meter. Would amp reading be accurate without engine running ? That internal resistance might be a bit high at 2.8 ? I have two coils, one from Bubba, and each read 1.8 last week. (granted 1.5 or above normal for 12v V8).

10-02-2016, 01:30 PM	#4
Dec211975 Senior Member Join Date: Feb 2011 Location: Monroe, Wi Posts: 247	Re: Amperage Draw with Ignition on? - Bubba Ignition Question Calculating the amperage with the numbers provided (12 volts, 2.6 ohms) the amperage should be 4.615

10-02-2016, 02:11 PM	#5
glennpm Senior Member Join Date: Sep 2014 Location: Wiscasset, Maine Posts: 1,981	Re: Amperage Draw with Ignition on? - Bubba Ignition Question Thanks Guys and Dec211975, I should have checked with Ohms Law like you did. I'm going to recheck my resistance and also see what Bubba may say. Thanks! Okay I remeasured and got about 2.3 ohms resistance so ammeter should be about 5 amps considering I measured about 11.7 volts at the ignition switch this morning. Last edited by glennpm; 10-02-2016 at 02:20 PM. Reason: added re-measure values

10-02-2016, 03:21 PM	#6
JSeery Member Emeritus Join Date: Nov 2012 Location: Wichita KS Posts: 16,132	Re: Amperage Draw with Ignition on? - Bubba Ignition Question Sponsored Links (Register now to hide all advertisements) You really need a ballast resistor with that coil value. You are looking for ~3.5 to 4 amps max and if you use the more realistic higher voltage numbers it will be about 4 amps. a charged battery with the engine not running should be around 12.6 to 12.7 volts and with the generator charging the battery it could in in the 14.7 or so range. 12.6V / 2.3 ohms = 5.5A & 14.6V / 2.3 ohms = 6.4A This is way to high and you need a ballast resistor in the circuit, it needs to be sized for the engine running current.

10-02-2016, 04:21 PM	#7
Step-down Senior Member Join Date: May 2012 Location: Hat City (Danbury CT) Posts: 647	Re: Amperage Draw with Ignition on? - Bubba Ignition Question When testing make sure your points are in the open position ..... To evaluate there isn't any other issue your dealing with first .... __________________ "I can't cry as long as I know the Lord has risen "

10-02-2016, 04:33 PM	#8
glennpm Senior Member Join Date: Sep 2014 Location: Wiscasset, Maine Posts: 1,981	Re: Amperage Draw with Ignition on? - Bubba Ignition Question Hi Jserry, Yes, I thought the amperage was too high too. Bubba's FAQ said to just make sure for a V8 that the resistance is greater than 1.5 ohms so I thought I was good until I noticed the high draw this morning on my 1932 dash ammeter. I'll put a ballast resistor in. Thanks

10-02-2016, 06:08 PM	#9
JSeery Member Emeritus Join Date: Nov 2012 Location: Wichita KS Posts: 16,132	Re: Amperage Draw with Ignition on? - Bubba Ignition Question 1.5 would be for like a 6v system OR a 1.5 ohm coil and a 1.5 ohm ballast resistor for a total of 3.0 ohms in the circuit on a 12v system. Without a ballast resistor the coil needs to be in the 3 to 4 ohm range.

10-02-2016, 11:12 PM	#11
Drbrown Senior Member Join Date: Oct 2013 Location: Glens Falls NY Posts: 1,267	Re: Amperage Draw with Ignition on? - Bubba Ignition Question glennpm .... following-up our pm exchange .... you have a Pentronix module in crab. The coil furnished with that should have internal resistor. Just communicated with Bubba's. The coil he sold me with my Pentronix was reading 1.8 ohms and he will confirm what a proper reading should be. That should answer your issue about ohm reading for your coil and indicate what amperage your module and coil would be expected to be drawing. As noted, friday a Pentronix Company Tech advised me their modules are designed to require a minimum of 9 volts and tolerate a maximum of 16 volts. They have been know to survive momentary voltage spikes in excess of 16 (I can attest to that). They are warranted for 30 months from sale for workmanship.

10-03-2016, 06:24 AM	#12
JSeery Member Emeritus Join Date: Nov 2012 Location: Wichita KS Posts: 16,132	Re: Amperage Draw with Ignition on? - Bubba Ignition Question Well, I missed the "converted" in the OP! Little things make a difference!!!!!