super c suddenly missing on 3 and 4

David G · Sep 29, 2011

I would roll with the compression check and verify the valves work correctly on those two cylinders.

Arossihman · Sep 29, 2011

after your compression check make sure you are getting enough fuel...its possible 3 and 4 are just being starved of fuel. we add in line fuel filters to all the older stuff. also i would look into electronic ignition for your c. did wonders for our m.

JRSutton · Sep 30, 2011

How do you know - or what do you mean - that it's not firing on those two cylinders?

Did you test for spark at each of the cylinders?

If not - grab an extra spark plug, and just pull each wire one at a time and use the spare plug to see if it's sparking.

If they're not, then you can focus 100% on the distributor.

If it is sparking all around, it doesn't prove things are 100% in the distributor, but good enough that you should move your focus to valves. Adjust the valve lash, and in doing so you should be able to see if any are stuck or not working properly.

Owen Aaland · Sep 30, 2011

A carbon trace in the distributor cap can cause the problems you are having.

It takes more voltage to fire a plug under compression so you can have a situation where if you pull a plug wire there will always be spark on that wire but when connected to the plug in the engine the spark will travel along the carbon trace to fire the plug that is not under compression.

El Toro · Sep 30, 2011

Wiggle the shaft where your rotor is attached and see if there's a lot of wear. Hal

Janicholson · Sep 30, 2011

A bad cap can be an indication of a bad or open spark plug wire! Check each with an Ohm Meter. If solid core, Near zero ohms. If carbon 5000 Ohms/ft.
if wound wire near zero ohms. Jim

super c suddenly missing on 3 and 4

David G

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Arossihman

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JRSutton

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Owen Aaland

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El Toro

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Janicholson

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