Capacitor unwell?

What to do with all those wires.

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MTJIM
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Capacitor unwell?

Post by MTJIM » Thu Jul 28th, 2011 3:47

Our 49 Plymouth will run for 30 minutes or so, then stop and can't be started. I initially though it was a contaminated fuel problem, which clogged up the carb, but had carb rebuilt, fresh gas, in-line filter, and plenty of gas from fuel pump to carb.

I may have problems with fuel mixture, as plugs get carboned up, and starting is hard.

I get a spark at the plug.

Our son had an order 60s car, and suggests that it might be the capacitor, which fails after warmup. He had similar problem. I have a new and correct capacitor.

Car had a complete mechanical rebuild in '09 at a re$toration place back east.

Any thoughts? New plugs? Local parts here said wouldn't be problem as capacitor is only for supression of static to the radio....but I don't think car ever had a radio, even when new...Perahps it got one as a "freebe"

Thanks,

Jim in Montana

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Re: Capacitor unwell?

Post by MTJIM » Fri Jul 29th, 2011 9:46

I suspect it may be the capacitor......fuel seems fine, but spark doesn't get a "snap" but perhaps I'm used to 12 volt system. Will swap that out and see what happens.

Astron 1949
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Re: Capacitor unwell?

Post by Astron 1949 » Tue Aug 2nd, 2011 1:36

Hi Jim,

Did changing the capacitor/condenser do the trick ?

If not, U may wish to check the Primary and Secondary resistances of the coil. Remove the 2 primary and the secondary wire, using an ohm meter between the coil negative and the secondary post, should produce between 5000 to 8000 ohms (mileage may vary, depending on coil makers.) Then connect ohm meter between Positive and Negative terminals. Reading should be +- 3 ohms, assuming its not a ballast resistor type. (1.5ohms, if it is.)

Make sure that the thin 'fly' wire from the distributor goes to the positive (+) pole on the coil. In other words, coil polarity should be the same as battery polarity.

btw that parts house person hasn't a clue.To state that it is only there to suppress radio interference is hogwash
The condenser is a critical part of a contact breaker ignition system. The condensor/capacitor absorbs a voltage spike, which is created when the coil's magnetic field collapses.
So,basically the purpose of a condenser is to reduce the spark at the contact points as they open and therefore minimise burning and pitting of the points.

More info later, if required :-) Cheers, Fred.

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Re: Capacitor unwell?

Post by MTJIM » Tue Aug 2nd, 2011 9:43

Fred,

Thanks for the input and background. Haven't had a chance to change the capacitor yet, but will try early next week. (headed out the the Little Big Horn battlefield for a few days.)

From what you say, this is electrical-related.

Will post what results with our '49.

Jim

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Re: Capacitor unwell?

Post by MTJIM » Thu Mar 8th, 2012 9:10

OK. Back into this...after an absence. Travel, winter...car should be just fine as is garaged with Stabul in tank.... Working the electricals today. Sorry about the delay.

More later...

Jim

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Re: Capacitor unwell?

Post by 194950dj » Thu Mar 8th, 2012 9:18

How about determining weather problem is fuel or ignition?. Pour a small amout of gas in carb, does it try to start or start AFTER this 30 mi. run time? if so fuel problem, try removing the gas cap (vent problem). If nothing happens, check for spark at plugs again after 30 min. problem, using an old good condition plug and connect to the coil wire and make sure it fires repetedly when cranked. If so, connect spark plug to one plug wire, does it spark about once per rev??. A bad condensor will give no spark( or intermittent) at all when hot.
A bad coil will do the same (most likely the cause, but condensors are way cheaper to try replacement!).

After these cheap checks, if fuel is the problem other checks can be done to isolate the problem with further
diagnosis and posts, :lol:

Happy MOPAR motoring
Doug

MTJIM
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Re: Capacitor unwell?

Post by MTJIM » Sat Mar 10th, 2012 6:42

Yep. It was the condenser. Quite a challenge getting the screw back in place, but got a screwdriver with a capture blade, and that worked fine.

Replaced the condenser :) , got fuel to the carb, and it started right up. Ran it around town about 10 miles and things worked fine. Car had a mechanical rebuilt several years ago. Always get a lot of smiles and waves when driving it. With so many unique classic cars saved from the crusher and on the road, who still drives a black, 3-speed, 4-door, family sedan?

Will post a couple of pictures on the my-car part of the forum.

Thanks for the suggestions...

Jim

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Re: Capacitor unwell?

Post by MTJIM » Tue Jun 18th, 2013 9:15

As update...after being run last summer, car went into a long Montana winter sleep...slo charger on battery, new fuel, stabilizer, tires checked, mouse sticky trap on back rear floor.

About a month ago, hooked up battery, and car fired up on first crank. A little air in left rear tire and we were good to goQQ

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