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Discussion Topic:
1936 idles great, misfires at load
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4dFordSC |
05-05-2019 @ 7:11 PM
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Member
Posts: 266
Joined: Oct 2009
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Coil or condenser. Send the coil to Skip Haney for rebuild (http://www.fordcollector.com/coils.htm), and replace the condenser (NAPA IH-200 works well with flatheads).
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MG |
05-05-2019 @ 6:53 PM
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Senior
Posts: 1250
Joined: Nov 2009
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Replace the condenser....
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maruapo |
05-05-2019 @ 4:17 PM
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Member
Posts: 6
Joined: Mar 2011
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Thanks for the suggestion, TomO. If you had to wager, what are the odds that instead it's a bad coil? I had a boat once that did this when you gunned it and it turned out to be the coil, so my head goes right there
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TomO |
05-05-2019 @ 8:38 AM
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Senior
Posts: 7244
Joined: Oct 2009
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Your problem could be insufficient fuel delivery. This condition shows up when driving at highway speeds as a miss or the engine dies. To check fuel delivery, you need a graduated 16 ounce or larger container to determine the amount of fuel delivered in a measured time. Disconnect the fuel pump line from the carburetor and direct it into a graduated container. Crank the engine long enough to get 2 ounces of gas in the container and then continue cranking for 15 more strokes of the pump. The pump should have delivered 6 more ounces of gas. Insufficient fuel delivery can be caused by a vacuum leak, plugged flex line, worn pivot in the pump arm, stretched diaphragm, plugged fuel line or tank pickup, plugged tank vent or wrong gas cap or a worn push rod. The push rod should be 8 7/8" long for the cast iron manifolds and 7 7/8" for the aluminum manifolds. It travel is about 3/8".
Tom
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maruapo |
05-05-2019 @ 8:19 AM
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Member
Posts: 6
Joined: Mar 2011
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My 1936 Ford flathead 68 6v is about as original as it comes. I had the distributor out a couple years ago, and b0th sets of points looked great, though I'm well aware that human eyes are no replacement for a distributor machine. Ignition coil, who knows what's going on but it seems fine. Spark plugs new, and every test of the spark results in the desired 1/2" blue flame; the plugs have no fouling. Anyway the car runs great. Idles beautifully. When parked, you can race it to high RPMs and it doesn't miss at all. But get it on the road, and put any stress on it whatsoever, and it misfires quite badly. I suspect distributor or coil. Heck just about everything related to ignition is suspect, but since it has no problems except at load I'd rather not rip rebuild/replace everything if it's just one little thing. Before I send the distributor to be rebuilt, or get a coil rebuilt, any thoughts on what's going on?
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