| kirkstad | -- 09-14-2020 @ 11:18 AM |
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I'm replacing my after market 6 volt coil that has an internal resister with my original coil for my 36, rebuilt by "Skip Haney. I want to make sure my under dash resister is reducing the voltage properly so I don't damage my coil.What voltage should my coil be getting at start up and running etc. and how would I test it. I have been bypassing it up until now. Thank you Frank
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| JayChicago | -- 09-14-2020 @ 5:15 PM |
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With engine stopped, you should see 3 volt at the coil, plus or minus a few tenths of a volt. (if you see 6 volt, indicates engine just happened to stop with points open. Bump the starter and test again) Then when engine is running (points open 20% of the time), voltage should jump up to 3.5 to 4 volt. EDIT: How to test Engine stopped: Connect volt meter negative lead (black) to input terminal on coil. Connect positive lead (red) to any convenient ground point on the engine. Turn on ignition switch and read the meter. Then turn off ignition switch right away. (you want to minimize time ignition is on with engine stopped, is then at maximum current flow, could be hard on the coil and points) Engine running: Same meter hook-up as above. Make sure meter leads can't get snagged by pulleys or fan belt. Don't stick your hand down there while engine is turning. Start engine and read the meter. This message was edited by JayChicago on 9-14-20 @ 5:55 PM
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| ford38v8 | -- 09-14-2020 @ 7:39 PM |
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Jay gave you excellent advice, I have only one bit to add: Your meter can be analog or digital for the static test, but must be analog for the running test, as with a digital, you'd only get multiple spots of meaningless light flashes! Alan
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| kirkstad | -- 09-15-2020 @ 9:40 AM |
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Thank you JayChicago and Alan, just the information I needed I really appreciate it.Stay safe! Frank
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| wmsteed | -- 09-15-2020 @ 10:44 AM |
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As I recall the resistor on the firewall is called a Ballast Resistor,.designed to provide full voltage to start, then reduce the voltage to the coil for running, to prolong coil, etc., life. This is an item that is over-looked by a lot of people. I lost several coils on my 36 during the first couple years I had the car, got to the point that I carried a spare coil in the car until I found out about the ballast resistor. Bill 36 5 win delx cpe This message was edited by wmsteed on 9-15-20 @ 10:49 AM
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| ford38v8 | -- 09-15-2020 @ 1:24 PM |
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Bill, the ballast resistor is simply that, the circuit goes through the resistor, period. Testing a no-load circuit will show full voltage, but with points closed, the resistor will cut voltage back. To provide full voltage to aid in starting, a bypass circuit (non-stock) can be wired in. Alan
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| JayChicago | -- 09-16-2020 @ 4:57 AM |
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Full bypass of the resistor on start was in common usage later, in the fifties. I don't know when/if Ford started doing that. I wish our cars had it. But ignition problems are usually not due to the resistor. The resistor is quite robust, rarely fails. Most old original resistors still function as designed. On the other hand... Our coil is a fragile part with internal tiny wire windings that is known to commonly fail. And the aftermarket coils have a reputation for being more fragile, with short life. A coil rebuilt by Skip Haney is known to be much stronger with longer life. A spare coil in the trunk is not a bad idea. This message was edited by JayChicago on 9-16-20 @ 7:55 AM
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| MICHV8 | -- 09-20-2020 @ 5:39 AM |
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I just looked and my 32 has a tube coil that states on the casing that it has an internal resistor and no external resistor is needed. Well, I looked under the dash and there is an external resistor mounted. The car starts immediately, so is the external resistor a problem?
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| kirkstad | -- 09-20-2020 @ 6:37 AM |
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When I installed the after market coil with internal resister on my 36, I disconnected the original coil wire and ran a wire to my new coil from the input side of my stock resister thus bypassing it. Check your wiring, it may have been done a different way. It would seem to me that if your stock resister was not bypassed in some way, your 32 may start but wouldn't run very well with the voltage being reduced twice. Frank
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| JayChicago | -- 09-20-2020 @ 1:31 PM |
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I agree with Frank. A likely explanation is that whoever installed that coil bypassed the resistor, but left the resistor in place for the future.
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