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Old 02-11-2018, 09:06 AM   #21
Bob Bidonde
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Default Re: Replacement Ignition Coil

Tom,
After 90 years of service, what do you think the remaining life is? I hope you have a spare coil if you tour out of town in your Model A.
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Old 02-11-2018, 11:57 AM   #22
Purdy Swoft
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Default Re: Replacement Ignition Coil

About the only thing that effects original tar filled model A coils is carbon tracks that extend up to the metal tube housing. Carbon tracks can short the coil but can be scraped off . Carbon tracks are mentioned in the service bulletins . Like Tom , Ive never had a problem with an original , even if it was beat up and rusty .

Last edited by Purdy Swoft; 02-11-2018 at 12:05 PM. Reason: added the letter w
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Old 02-11-2018, 12:36 PM   #23
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Default Re: Replacement Ignition Coil

Quote:
Originally Posted by 40 Deluxe View Post
Answer: It depends!......Depends on how much voltage is needed to jump the plug gap. If only 5,000 volts will fire the plug, that is all the coil will put out. Even if you have a double super whammy "40,000 volt" coil it will still only build up secondary voltage to the point where the spark is strong enough to jump the plug gap, which will never reach 40,000 volts on a Model A, or any stock engine (unless you have totally burned out plug electrodes or open wires, etc.). An ultra high compression or supercharged engine running at wide open throttle may need this much voltage capability, though.
To test coil output, try a "Lisle #20700 Spark Tester". Or, go to a shop with a scope, hook it up and pull a plug wire off and watch the screen.
If this was really the case, no matter what coil or distributor that was used would increase the spark . This is really no so !!! I use a gap of .035 - thats thirty five thousants at the spark plugs . Running at idle speed is not an extra strain on the coil . Idle speed doesn't require extra voltage to jump the .035 gap at the spark plugs. If my Flame thrower coil doesn't increase the spark . Why would the idle rpm increase to the point that I had to readjust the idle speed . I have had similiar results with other performance coils like the 30.000 volt bee hive coils . These coils give performance that a person that has actually used one can't deny .
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Old 02-11-2018, 02:07 PM   #24
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Default Re: Replacement Ignition Coil

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Hi Purdy! Yes, I have a 40611 Flame Thrower, but it failed so I replaced it with a Bosch 00012 (Blue Coil).

I usually look at this forum several times a day . I haven't seen any inconsistant voltage ratings of the Flamethrower type coil that I use posted on this forum . I do remember a post where Mr HL Chauvin posted what one of the Pertronix engineers told him . There was no mention of a voltage difference between the 1.5 ohm and the 3.0 ohm versions of the flamethrower coils . The engineer hinted around that the 12 volt 3.0 version could be the better choice for performance . You question the voltage out put of the Flamethrower coil . What is the advertised voltage of the Bosch 00012 coil ??? If Flamethrower coils have been recalled, WHY hasn't my coil been recalled ? You mention and post a picture of the Bosch 00012 coil , mounted on your car . Post number 14 states that he uses a blue oil filled Bosch coil like yours . If your Bosch coil is oil filled you have yours mounted upside down . Oil filled coils that are mounted wrong usually fail early , no matter what brand that they are . If you used the lower priced oil filled Flame thrower coil and mounted it wrong, that could be the reason that it failed . The solid epoxy coil can be mounted as original , not necessarily so with the oil filled version .

I use the 40611 epoxy coil . Mine is the 3.0 ohm 12 volt version . I use the original model A distributor with original style points . Pertronix makes different coils for electronic ignition . Using the 40611 with electronic ignition could be a problem .
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Old 02-11-2018, 04:31 PM   #25
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Default Re: Replacement Ignition Coil

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Originally Posted by 40 Deluxe View Post
Answer: It depends!......Depends on how much voltage is needed to jump the plug gap. If only 5,000 volts will fire the plug, that is all the coil will put out. Even if you have a double super whammy "40,000 volt" coil it will still only build up secondary voltage to the point where the spark is strong enough to jump the plug gap, which will never reach 40,000 volts on a Model A, or any stock engine (unless you have totally burned out plug electrodes or open wires, etc.). An ultra high compression or supercharged engine running at wide open throttle may need this much voltage capability, though.
To test coil output, try a "Lisle #20700 Spark Tester". Or, go to a shop with a scope, hook it up and pull a plug wire off and watch the screen.
Excellent post, this is the way I always remember it, using an oscilloscope can teach you much about the ignition system, spark plug cleaning machines had voltage testers built into them.
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Old 02-11-2018, 04:52 PM   #26
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Default Re: Replacement Ignition Coil

So can the 40611 Pertronix coil, epoxy filled be used on a stock 6 volt system?

Thanks
paul
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Old 02-11-2018, 05:15 PM   #27
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Default Re: Replacement Ignition Coil

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So can the 40611 Pertronix coil, epoxy filled be used on a stock 6 volt system?

Thanks
paul
From their web site, for 6 volt systems use part number 40111 1.5 ohm epoxy.
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Old 02-11-2018, 07:02 PM   #28
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Default Re: Replacement Ignition Coil

jmeckel

Thank you

Paul
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Old 02-11-2018, 07:15 PM   #29
Tom Wesenberg
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Default Re: Replacement Ignition Coil

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Originally Posted by Bob Bidonde View Post
Tom,
After 90 years of service, what do you think the remaining life is? I hope you have a spare coil if you tour out of town in your Model A.
Sparks must be really small, because I'd have thought that size can would have emptied out years ago.
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Old 02-11-2018, 08:36 PM   #30
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Default Re: Replacement Ignition Coil

Tom's coil is authentic ..... "any color as long as it is black"
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Old 02-11-2018, 09:08 PM   #31
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Default Re: Replacement Ignition Coil

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Originally Posted by Purdy Swoft View Post
If this was really the case, no matter what coil or distributor that was used would increase the spark . This is really no so !!! I use a gap of .035 - thats thirty five thousants at the spark plugs . Running at idle speed is not an extra strain on the coil . Idle speed doesn't require extra voltage to jump the .035 gap at the spark plugs. If my Flame thrower coil doesn't increase the spark . Why would the idle rpm increase to the point that I had to readjust the idle speed . I have had similiar results with other performance coils like the 30.000 volt bee hive coils . These coils give performance that a person that has actually used one can't deny .
The increase in idle speed was from opening the plug gap to .035". The increased gap allows for more fuel molecules to be available to be ignited by the spark, so idle speed increases (and emissions go down). In the '70's came stricter emissions laws. One way manufacturers met the standards was with leaner mixtures which required larger plug gaps to cut down on misfire. This required higher voltage coils and in turn better plug wires (most manufacturers went to 8mm wires). EPA also required cars to run longer without a tuneup so electronic ignition systems came into use. Ford went to about .050" gaps , most GM went to .045" gaps, and some Oldsmobiles used .080" for awhile.
Try setting two plugs in your A at .025" and two at .035" and hook it to a scope. Record the firing voltages. Then set the two plugs back to .035". You will see an increase in voltage on those two plugs. Next put on a stock A coil and see if the voltage changes from your 'hot' coil.
When the points open and voltage is induced in the secondary circuit, it only rises enough to jump the plug gap, no matter the coil's potential. With your A on the scope, pull the coil wire out of the distributor cap and watch the voltage rise on the scope as you hold the wire further away. In this case the 'hot' coil will produce a longer spark than the stock coil, because it has more voltage potential in reserve. In normal use, this higher potential is never reached.
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Old 02-12-2018, 12:17 AM   #32
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Default Re: Replacement Ignition Coil

40 Deluxe is correct
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Old 02-12-2018, 01:07 PM   #33
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Default Re: Replacement Ignition Coil

I believe that Ford increased spark plug gap to .035 before model A production ended ... Anyway , I have always set my spark plug gap at .035 on my model A's and most others with points ignition . Spark plug gap had nothing to do with the rpm increase after installing a performance coil . The reason being that the gap had allways been at .035 , not readjusted to .035 after the installation of the flame thrower coil .I agree that more spark plug gap , to a point better burns the fuel . I agree that spark plug gap increased with the introduction of electronic ignition . The coils would have had to have been improved to handle wider spark plug gaps . Standard , ( not necessarily brand) , replacement coils for points ignition will fail rather quickly If the gap is opened too wide ! I have used other performance coils and they all increased idle rpm and noticably improvement performance . This is my experience .
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Old 02-12-2018, 01:19 PM   #34
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Default Re: Replacement Ignition Coil

your claim about better performance would not be measured by most by a change of rpm at idle, which isn't much of a yardstick.
Are there any dyno data to support this claim. What is happening at speed is the real measure.
Somehow 10K volt coils got us thru the first 80 years of the Model A, and suddenly they are inadequate?
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Old 02-12-2018, 01:49 PM   #35
Purdy Swoft
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Default Re: Replacement Ignition Coil

I figured that would be the next negitive comment . As I have said many times before , I have nothing to prove or gain here. Actually I never said that idle rpm was the test of increased power. Performance coils obviously are not for everyone . You could probably find a coil that would fill your needs , if you need one . at NAPA.
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Old 02-12-2018, 06:34 PM   #36
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Default Re: Replacement Ignition Coil

already did, car runs fine
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Old 02-12-2018, 09:23 PM   #37
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Default Re: Replacement Ignition Coil

My tudor has the coil that was on the car when I bought it 43 years ago. It runs fine.
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Old 02-12-2018, 10:46 PM   #38
Purdy Swoft
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Default Re: Replacement Ignition Coil

None of the model A's that I have now even had a coil when I got them .
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Old 02-13-2018, 02:44 AM   #39
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Default Re: Replacement Ignition Coil

Quote:
Originally Posted by Purdy Swoft View Post
I believe that Ford increased spark plug gap to .035 before model A production ended ... Anyway , I have always set my spark plug gap at .035 on my model A's and most others with points ignition . Spark plug gap had nothing to do with the rpm increase after installing a performance coil . The reason being that the gap had allways been at .035 , not readjusted to .035 after the installation of the flame thrower coil .I agree that more spark plug gap , to a point better burns the fuel . I agree that spark plug gap increased with the introduction of electronic ignition . The coils would have had to have been improved to handle wider spark plug gaps . Standard , ( not necessarily brand) , replacement coils for points ignition will fail rather quickly If the gap is opened too wide ! I have used other performance coils and they all increased idle rpm and noticably improvement performance . This is my experience .
Now you've got my curiosity up! How much was the increase in idle RPM? I need to do some experimenting to see if I can duplicate your results.
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Old 02-13-2018, 10:45 AM   #40
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Default Re: Replacement Ignition Coil

40 Deluxe, help me to understand what that would have to do with performance at speed, which is where the real money is

anyone got a dyno handy?

I suspect that somehow the timing was changed slightly
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