1940 ford flathead

[averillandchris]

Hi i'm new to this so I hope I can do things right. I have a 40 woodie and it starts and runs fine untill I try to drive it. Frist gear is fine but when I go to second it starts to miss fire and I have a hard time getting back to the shop. Not sure what is happening Any info would be great thanks

[ActionYobbo]

Start at the distributor. Timing, points, vacuum brake, plug wires and plugs.
After all that’s verified and it’s still doing it then change the coil.

[JayChicago]

Welcome to FordBarn. Hope we can help you.

I think your problem could be so many different things that any of us posting a possible cause would just be guessing. I would suggest you start with the basic diagnosis to at least determine if it is a fuel problem or a spark problem:

When it acts up, look down into the carburetor while moving the throttle arm. You should see two squirts of gas. If no squirt, indicates a fuel delivery problem.

When it acts up, while idling or cranking with starter, use a pliers to hold a spark plug wire about 1/2" from engine. Should see a blue spark that can jump about 1/2". If not, indicates a problem somewhere in the ignition syatem.

[tubman]

Sound like a classic condenser/coil problem to me.

[Zeke3]

Originally Posted by JayChicago

When it acts up, while idling or cranking with starter, use a pliers to hold a spark plug wire about 1/2" from engine. Should see a blue spark that can jump about 1/2". If not, indicates a problem somewhere in the ignition syatem.

Be sure to use pliers with insulated handles or plastic pliers for the above test.

I agree with Tubman, condenser or coil. If you stop and put it back in first gear, does it run okay until you shift to second?

Welcome to the Barn.

[averillandchris]

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Thanks for the help. The only thing I have not change is th condenser. I have good spark and it startes like a new one and idle just fine. I can rev up the motor with no problem and it sounds good. It only gives me problems going down the road. thanks for getting back to me.

[Ken/Alabama]

Could be a crack in the rotor and arcing to the shaft.

[kurt v]

Has your carb been cleaned real good, are you using ethanol fuel and good power valve installed?

[slowforty]

Zeke X 2

[slowforty]

Also dont lean against the fender

[JayChicago]

Originally Posted by tubman

Sound like a classic condenser/coil problem to me.

Tubman, please help me understand this. Original post said "Frist gear is fine but when I go to second it starts to miss fire". Why would condenser/coil problem show itself in second gear?

[38 coupe]

The spark intensity requirement goes up with engine load. You can get away with a weak spark when free revving an engine. You need a bit better spark to pull first gear. You need an ok spark to pull second gear. You need a good spark to go down the freeway in high.

[tubman]

Couldn't have said it better myself.

[JayChicago]

Makes sense. Thanks.