I Got A Nasty Engine Miss . . . . . .

[grey beard]

My motor starts and runs like Walter P. wanted every engine to sart and run. Sounds like a Swiss watch. Pulls fine on hills and goes down the road right sweetly . . . . . . UNTIL I get up to about 2000 - 2500 RPM, then it begins to break up and miss. Will NOT go above this engine speed. Sortaa' like a governor kicking in.

So far, I've tried adjustinmg the points, played with the timing a little, pulled the distributor and checked the ground wire on the breaker plate and checked the vacuum advance uinit, disconnected my pcv system, and scratched my head alot. Still no joy. Nothing I do seems to affect this problem.

This engine ran well AND ran up to the top speed just fine before the major overhaul. Overhauled the carb, everything in the ignition system is brand-splimter-new. I'm about ready to pull the carb apart again to see if something there is unhappy.

Any advice, local wisdom or suggestions of a practical nature? There's not a nicer starting and running engine around, UNTIL I raise the speed to the top third of the rpm band.

Mebby it's gremlins .. . . . . mebby they hate me .. . . . .

__________________

[Jerry Roberts]

Perhaps it gets gas , but not enough gas for needs at the higher RPM's ? Weak fuel pump , restriction in line or tank ? Vented gas cap ?

[greg g]

Check the wire in the distributor, if the innsulation has deteriorated, it can ground out against the body when the vacuum advance moves the breaker plate. I found that mine was bad, rathere than trying to replace the wire, I reinsulated ti by windig it with silk thread that then coated with rubber cement.

Also next time you have it running for a while touch the coil, it it is hot to the tough, it may be bteaking down.

[Don Coatney]

Dave;

What are your spark plugs gapped at? Have you taken a plug "reading". Suggest you drive down the road at the RPM range where the engine is miss firing. As soon as the miss firing begins dump the clutch and kill the ignition. Coast to a stop and pull the plugs for a reading.

[greg g]

Whats the temp down there?? Any possibility your choke is sticking or your heat riser is not operating????

[Dodgeb4ya]

Had an engine do just that- High RPM under heavy load severe miss. Ended up being weak valve springs.

Bob

[grey beard]

Choke is mechanical. Dist. wires are all checked and fine. Fuel pump is a new electreic Walbro with all new lines and clean tank.

Anybody ever run into a problem like this that was carburetor related - other than basic fuel supply? I'm baffled . . . . . .

[kevinanderson]

My plymouth did the same thing. tune up with high quality cap rotor(No aluminum) wires etc cleaned it up.

[Rodney Bullock]

Choke is mechanical. Dist. wires are all checked and fine. Fuel pump is a new electreic Walbro with all new lines and clean tank.

Anybody ever run into a problem like this that was carburetor related - other than basic fuel supply? I'm baffled . . . . . .

Grey Beard, are the plugs you are using the same as the ones you used before the rebuild, long plugs verse short plugs. Please check the coil sometimes if the coil is weak it will not work past a cetain rpm.

[Merle Coggins]

In your post on the truck page I suggested checking your fuel pump / fuel supply. But if you have all new lines and a good pump maybe it is something else. However, when there is a problem nothing should be overlooked no matter how "new" it is.

If you suspect the carb... maybe there's a piece of schmutz partially plugging the main jet restricting how much gas gets into the mix. This would cause a very lean mix under load and may manifest itself as a miss.

Merle

[Young Ed]

I think I'd pop the top of the carb and look at the float level too.

[Jerry Roberts]

It is quick and easy to see if you are getting enough fuel to the carb . Disconnect your fuel line where it connects to the carburator and turn on the electric pump and watch the amount of flow into a bucket .

[old woolie]

A bad condenser will sometimes cause the symptoms that you are experiencing.

[busycoupe]

This is kind of a long shot, but I remember when I was working in a service station back in the early 70's we had GM wagon come in with a problem just like this. It turned out that the exhaust pipe was double walled and the inner wall had collapsed. The car would start and run great, but at speed it just ran out of power, as if it were starved for gas. You might check for obstructions in the exhaust system.

[grey beard]

Busycoupe,

Thanks - good thought. I've seen the same problem when I worked for Ford Motor Co as a service instructor. That double wall pipe led many a good man down the garden path. This exhaust is the same one that was on the engine when it accelerated just fine, before the overhaul. My thinking at this point is that either the condenser is fluky or I did something wrong when I assembled the carb, when I put the new kit in it. Hope to find out more soon.

Thanks

[FMSPEED49]

I had a very similar problem, It turned out to be the centrifugal advance under the breaker plate, They use to "grease" them. I had to take it apart and clean the hell out of it to remove the sticky residue. The vac advance tested fine, but it only controls part of the mechanism. The side I am talking about is the weighted spring side.