11-25-2018, 04:30 PM | #1 |
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weak spark
This is a 1954 239 with a 57 dist. car started missing bad last time out, had to be towed home. replaced dist cap and rotor. points and condenser, plug wires and plugs.coil also replaced.. no help looks like weak spark. I am out of ideas.
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11-25-2018, 06:28 PM | #2 |
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Re: weak spark
If you pull the coil wire out of the dist. cap, see if there is a good strong blue spark when holding the end of the coil wire close to a ground. Should jump a good 1/2" gap.
If good there, then do the same thing at one of the spark plugs. That will at least tell you if the spark is strong enough to run good. Sal |
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11-25-2018, 06:59 PM | #3 |
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Re: weak spark
I had a similar problem and turned out to be a bad brand new coil from NAPA. About went crazy trying to find problem but did as stated above and traced it back to the coil.
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11-25-2018, 10:46 PM | #4 |
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Re: weak spark
What's your voltage at the coil while running? Check your resistor and check all your engine grounds. Had bad connections on mine that drove me nutz till I figured it out.
https://fordbarn.com/forum/showthrea...oltage+running |
11-26-2018, 01:32 AM | #5 |
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Re: weak spark
Are you still running the original 6 volt system? If so, the battery is positive ground and the primary wire from the ignition switch to the coil attaches to the "-" or "ign" terminal and the wire running to the distributor goes on the "+" or "dist" terminal.
Remove, clean and retighten all electrical connections (including grounds and battery terminals) in the ignition circuit, then take your ohm meter and check plug and coil wire resistance, coil resistance, resistance from "hot" battery cable to battery side of primary coil terminal (battery ground disconnected and ignition switch on), and resistance from (removed) battery ground cable to timing cover next to distributor base. All these readings should be nearly zero except for the coil itself (and the resistor if 12 V). |
11-26-2018, 12:06 PM | #6 | |
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Re: weak spark
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Quote:
It affects the intensity of the spark at the plugs. |
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11-26-2018, 06:55 PM | #7 |
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Re: weak spark
ok we got a fix. How about 3 bad condensers. do not buy advanced auto parts condensers. Put in napa ecklin and it runs great. thanks for every ones input.
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11-26-2018, 09:11 PM | #8 |
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Re: weak spark
Thanks for posting the fix. Have to say it doesn't surprise me, with all of the bad stories I've heard over the past few years about Chinese ignition parts.
Sal |
11-27-2018, 08:39 AM | #9 |
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Re: weak spark
36 flathead, can you give us the model number of that condenser please? There are a handful listed on Napa's site. Thanks!
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11-27-2018, 12:30 PM | #10 |
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Re: weak spark
GENUINE FORD IS STILL AVAILABLE - Points - B8Q 12171-A (MOTORCRAFT - DP-12) Condenser - C9AZ 12300-A (MOTORCRAFT - DC-13-A) Dealer - Amazon - Summit
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11-27-2018, 12:50 PM | #11 | ||
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Re: weak spark
Quote:
Quote:
Mike |
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11-27-2018, 05:13 PM | #12 |
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Re: weak spark
I agree, thanks for posting the fix. Always helpful to the rest of us who are going through something similar.
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11-27-2018, 08:58 PM | #13 |
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Re: weak spark
napa p/n points cs755 condenser fa 82. this is a 1957 distributor in a 1954 239 engine.
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11-28-2018, 12:17 PM | #14 |
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Re: weak spark
My curiosity has gotten the better of me and I'd like to make sure I'm not mistaken about a couple things.
I'm very sure a '54 239 would have had a smaller bearing diameter 'early' camshaft that meshed with a 13 tooth gear on the distributor & oil pump drive shaft, which used a flat/slot drive, unlike the more usual ('55+) 14 tooth gear with hex drive shaft. The assumption being... in order to put a '57 distributor into a '54 239 engine you'd have to change the distributor drive gear from 14 to 13 tooth, also the oil pump drive shaft and likely the oil pump too. There may(?) be early and late versions of the 239 with the updated size cam that used larger(?) bearings and 14 tooth drive gear. . Last edited by dmsfrr; 11-28-2018 at 03:42 PM. |
11-28-2018, 12:51 PM | #15 |
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Re: weak spark
Dmsfrr,
I was wondering the same thing when this was first posted, but assumed all of those changes were made. Sal |
11-28-2018, 01:31 PM | #16 |
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Re: weak spark
Thanks! I bought a new condenser from O'Reilly and it fried within the first few hours. I'll check out those Motorcraft ones!
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11-28-2018, 05:31 PM | #17 | ||
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Re: weak spark
Quote:
Quote:
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11-28-2018, 05:44 PM | #18 |
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Re: weak spark
This is a 239 with 13 tooth gear. I used a 57 dist with my original 13 tooth gear. I also used later oil pump to match. this was a pretty common conversion for better distributor
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11-28-2018, 06:17 PM | #19 |
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Re: weak spark
KULTULZ and 36 flathead, thanks for the confirmation.
The first and so far only Y-block powered car I've got ('55 Bird) came to me barely running with a bizarre mix of '54, '55/'56 & '57 engine parts. The initial process of making sense of the engine mess was confusing. Good to know it appears I learned something. Thanks again. Dennis |
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