Engine cutting out under load

[Don-Ohio]

As I was driving a month ago, the engine started "missing" under load as the engine wound out. It really felt like when the spark wasn't advancing) I figured timing/spark advance, but it looked fine. So I looked at carb, thinking maybe it was starving. put on spare carb; but same problem. Head/ manifold gaskets are fine, valves are a little out( a few thousanths bigger gap than needed) so not enough to cause this. I even took muffler off in case an critter plugged it up. The engine was rebuilt 2000 miles ago and the only thing left I can think of is some kind of spark problem (new plugs put in )... Any ideas?? The engine runs pretty smooth at idle and at an easy pace, but as soon as it winds out or going up a hill, it just is cuts out.

[Tom Wesenberg]

It could be a weak spark. You need at least 1/4" of hot blue spark when the coil wire is held near a head stud, and the engine cranked with the key ON.

If that's good, then remove the gas line at the carb and hold it over a quart bottle and see if it gives a good steady flow for several seconds.

[Don-Ohio]

I'll check the spark, I had purchased a new upper and lower plate for the dist. with modern points, so I went ahead and put that on. I guess coil could be bad. I already tried gas flow and it looks good, I pulled both filters out of my lines and they are good. ( also used new gas)! thanks

[Chuck Kuntz]

I had that same problem with the modern upper and lower plates that I purchased from Bratton's. Bad miss on a pull. I just switched back to the original design and the miss was gone.

[700rpm]

More likely a condenser than the coil. Go back to original plate and points. Make sure the points are gapped correctly. (.020)

[Jim Brierley]

Sponsored Links (Register now to hide all advertisements)

It is undoubtedly an ignition problem.

[jrelliott]

If you have the Modern Points set up where there is a metal tab making contact from the lower plate to the upper plate, this is a jury rig at best and it will fail. Take the two brass parts out and run an insulted wire from the top to the bottom plate similar to the original configuration where the two brass parts made contact from the top to bottom and will no longer have this problem. Just be sure to route the wire so will not touch the side of the distributor and rub the insulation off. JMHO

[Purdy Swoft]

I would also go back to the original points. I never had anything but problems with the so called modern points.
If you are using the wireless lower plate with modern points, that is another potential problem. The brass tab that extends from the upper to lower plate has a tendency to short against the housing and cause problems. The wireless lower plate with the acorn nut is good when used with original points. I set my points at .022 . If there is some wear in the distributor bushings the .022 gap will help maintain a not too close gap as the distributor cam rotates, the larger gap will give more time before the points have to be reset because of rubbing block wear. Usually if the coil is going bad, it wont start acting up untill the engine gets in a strain. If the float in the carburetor is not set pretty close to the correct setting it can be starving for gas and cause backfiring and running rough when you attempt to accelerate. A too lean setting at the GAV can have a similiar effect. I would also check if the coil is getting hot when it starts to act up. If you happen to have an oil filled coil, it will need to be mounted with the tower and wire connections pointing up, the reason being that the oil cools the internal windings and if mounted the way that original coils are mounted the oil won't reach the top of the windings. If the coil is the oil filled type, you can shake it and hear the oil inside.

[columbiA]

I have found that a 12-volt coil with an internal resister will work fine in a 6-v model A.