weak spark

[36 flathead]

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.

[scicala]

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

[50fordcoupeman]

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.

[wbedwards]

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

[40 Deluxe]

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).

[dmsfrr]

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Originally Posted by 40 Deluxe

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.
. . .

Yes, the ignition coil is polarity sensitive and needs to match how the battery of the car is wired.
It affects the intensity of the spark at the plugs.

[36 flathead]

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.

[scicala]

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

[bfdinardo]

36 flathead, can you give us the model number of that condenser please? There are a handful listed on Napa's site. Thanks!

[KULTULZ]

GENUINE FORD IS STILL AVAILABLE -

Points - B8Q 12171-A (MOTORCRAFT - DP-12)

Condenser - C9AZ 12300-A (MOTORCRAFT - DC-13-A)

Dealer - Amazon - Summit

[Black Fifty]

Originally Posted by 36 flathead

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.

Glad you got it fixed and thank you for posting the experience!

Originally Posted by scicala

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

Yeah, I've been hearing alot about "new" condensers lately too.

Mike

[Ford56]

I agree, thanks for posting the fix. Always helpful to the rest of us who are going through something similar.

[36 flathead]

napa p/n points cs755 condenser fa 82. this is a 1957 distributor in a 1954 239 engine.

[dmsfrr]

Originally Posted by 36 flathead

... this is a 1957 distributor in a 1954 239 engine.

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.
.

[scicala]

Dmsfrr,


I was wondering the same thing when this was first posted, but assumed all of those changes were made.


Sal

[bfdinardo]

Thanks! I bought a new condenser from O'Reilly and it fried within the first few hours. I'll check out those Motorcraft ones!

[KULTULZ]

Originally Posted by dmsfrr

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.

There were two 239's in 1954, the DIF (Detroit) and CLV (Cleveland).

One thing that ALL the '54 engines have in common is that they use a tang/slot type shaft to drive the oil pump. This carried into early '55, when it was superseded by the "hex" type shaft. This can make things a bit complicated if you want to change either the distributor or the oil pump, as the early pump is no longer available new. For most Y blocks, you can either switch to a '57-later distributor (a good idea) or at least swap in a '55-'56 hex drive dizzy.

However, there IS no 13-tooth hex gear distributor for the Dearborn, so you either have to keep the early pump style.... OR... you can, however, use a later distributor in the Dearborn, if you swap the gear to the early 13-tooth gear. Keep in mind that to do this for ANY '54/early '55 Y block, you also have to get the hex intermediate shaft, and a later oil pump, so it's a bit more involved than a simple dizzy swap.

https://www.jalopyjournal.com/forum/...tion-s.245502/

[36 flathead]

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

[dmsfrr]

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