Pertronix Coil for a CA
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Category: Allis Chalmers
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URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=170651
Printed Date: 23 Aug 2025 at 5:24pm
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Topic: Pertronix Coil for a CA
Posted By: sparky
Subject: Pertronix Coil for a CA
Date Posted: 28 Apr 2020 at 8:40pm
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Which pertronix flamethrower coil should I use for one of these modules a 1.5 or 3 ohmes? TIA. ------------- It's the color tractor my grandpa had! |
Replies:
Posted By: DiyDave
Date Posted: 29 Apr 2020 at 4:53am
IIRR, its a 3 ohm... ------------- Source: Babylon Bee. Sponsored by BRAWNDO, its got what you need! |
Posted By: jaybmiller
Date Posted: 29 Apr 2020 at 5:30am
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I'd assume 1.5 ohm is for a 6 volt battery , 3 ohm for a 12 volt battery, Those numbers give 4 amps of current to the coils. ( 6/1.5), (12/4). Jay ------------- 3 D-14s,A-C forklift, B-112 Kubota BX23S lil' TOOT( The Other Orange Tractor) Never burn your bridges, unless you can walk on water |
Posted By: Steve in NJ
Date Posted: 29 Apr 2020 at 6:19am
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Depends greatly on which system yer' runnin'. If its still 6V use the 6V coil. If its a 12V conversion, 4 cylinder's on 12V's need 2.7-3.3 ohms of resistance in the ignition circuit, so the 3.0 ohm coil is the ticket. The 1.5 ohm coils work fine with 6 & 8 cylinder engines. We have the 3.0 ohm coils in stock if interested..... Steve@B&B bb-customcircuits.com ------------- 39'RC, 43'WC, 48'B, 49'G, 50'WF, 65 Big 10, 67'B-110, 75'716H, 2-620's, & a Motorhead wife |
Posted By: frnkeore
Date Posted: 29 Apr 2020 at 12:49pm
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Please correct me, if I'm wrong but, a few months ago, I was reading about the Pertronix conversion and the coil needed. As I remember, the conversion needed the 1.5 ohm coil, used with a resistor if 12V. I bought a 3 ohm Pertronix coil to use with a 12V, point system (w/o resistor). If I try to use a 1.5 ohm coil, with direct 12V, it burns the points, in a very short time. ------------- Frank 1959 D17 Series I #24001+, '59 D14 '55 & '59 Ford 850 & 861 Ferguson TO 35 Deluxe, Oliver 70 and 5 more. |
Posted By: jaybmiller
Date Posted: 29 Apr 2020 at 4:22pm
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old school rule..for the Kettering ignition system( grade 9 autoshop..) points 'like' 4 amps running through them.. supplies enough energy to a coil, but won't burn the points. so 6 V / 1.5 ohms = 4 amps...points are happy. 12 V / 1.5 ohms = 8 amps.... burnt points, ouch ! EI system still have to supply power to the coil, but you need to read what the coil wants and MATCH it to the EI system. ------------- 3 D-14s,A-C forklift, B-112 Kubota BX23S lil' TOOT( The Other Orange Tractor) Never burn your bridges, unless you can walk on water |
Posted By: Steve in NJ
Date Posted: 29 Apr 2020 at 4:47pm
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I have no clue what you read, but the 1.5 Ohm coil works great with 6 & 8 cylinder engines. As I said, when running a 4 cylinder on 12V's you need 2.7-3.3 ohms in the ignition circuit for the engine to run correctly and to keep the points in service for a long time. Steve@B&B ------------- 39'RC, 43'WC, 48'B, 49'G, 50'WF, 65 Big 10, 67'B-110, 75'716H, 2-620's, & a Motorhead wife |