Bucking like a horse

[rbone]

If you want some help, I know a very good mechanic who lives about 30 minutes from Conyers, GA who has flathead experience. COVID has him only working 4 days per week, so he may be able to help. Let me know.

[Heard]

Kelly - do you have a timing light?

The reason I ask is because I recently had the similar symptoms on my '36 coupe. I had let it sit just a little too long, or so I thought. I hadn't cranked it in a couple of 4 months. When I finally got it to crank it was running really rough and backfiring. I thought it HAD to be gunked up carbs even though I always use the real gas. No corn gas for my coupe.

After a fair amount of scratchin' my ass I finally broke out the timing light and discovered that 2 of my plugs were mis-firing really bad. Now keep in mind it was running perfectly the last time I drove it. Plugs looked good but were just intermittent. Why??? I don't have any idea. But a new set of plugs solved my issue.

[JayChicago]

How did the timing light let you know you had bad plugs?

[40 Deluxe]

Originally Posted by JayChicago

How did the timing light let you know you had bad plugs?

Clip the plug lead onto each plug wire. If the light does not flash, you've found a bad plug.

[flatheadmurre]

Even if a plug would be dead or the carb is full of gunk they usually just miss...
Bucking and backfiring is usually condensor or arcover in rotor/cap.
After changing condensor i would carefully inspect all distributor parts before starting to tear down and change more parts.

[Tinker]

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to add... sticky valves will buck your system. I'd look at the condenser also. Get a vacuum gauge.

[Heard]

Originally Posted by 40 Deluxe

Clip the plug lead onto each plug wire. If the light does not flash, you've found a bad plug.

Exactly! Very easy to see.