Crunning poorly at full throttle

Pulling the choke a little doesn't help? If it does, there's a restriction in the carb, main needle not adjusted correctly, or a vacuum leak. Did you set the timing? Changing the points will change the timing. Overly advanced timing will make it sputter at rated speed. Is the distributor shaft wobbly in the bushings? The points cannot be properly set if the distributor shaft bushing is worn.

Not all carbs for the C had an adjustable main needle. Points are set at .020 and plugs .030 if I remember correctly. Another discussion a while back was new doesn't necessarily mean good. If you still have the old condenser, put it back in and see what happens. There could also be an internal leak in your carb. I have a similar carb on an Oliver 60 and it can be set to idle ok, or run ok above 1/2 throttle, but not both. I keep thinking I'll send it off to Steve in NJ to straighten out, but haven't gotten a "rountuit" yet...

I have a much smaller zenith carb that is off of a 38B. It is half the size of the MS carb. I may try it to see if it changes the way it runs. I just ordered the main carb gasket from Sandy Lake. The zenith had a bad gasket.

So there's not two screws, one for idle air and one for high speed run? Sounds like there might be the wrong high speed jet or none at all. I had that happen in a VW I rebuilt long ago for a friend. Didn't perform well and used lots of gas. Lots of new engine parts didn't change it. VW mechanic finally decided to check for a main jet and it was missing.

The idle screw only adjusts decently at very slow speeds.

The governor HIDEs adjustment effects. You have to override the governor or use it as an indicator. With the governor held off, you adjust for the fastest engine speed. If you can't hold off the governor, then you need to watch the throttle shaft or segment and adjust the mixture for the minimum throttle opening. That's the governor hiding the effects of your adustment.

Gerald J.

I had one running like that did everything you have done still didnt fix. Finally checked the air breather tube , dirt dobbers had the air choked almost off.  You might check that if you havent allready.

So true that the mixture depends on the air flow cleanliness before the carburetor. Bugs and birds like to nest in intake pipes and air cleaners. On my gas 4020 the Donaldson precleaner top was domed down contributing to it running rich.

One other cause of air flow restriiction can be accumulated grunge in the mesh of the vintage oil bath aircleaner. I recall many a time on this forum when part of the restoration involved burning that mesh to get rid of the accumulated grunge that limited air flow. I don't know that's good for the assembly, but its hard to clean.

Gerald J.