Make over for the CASE DC carb.

Greenfrog · Jul 26, 2017

1952 CASE
Carb needed to be cleaned/kit done. Local mechanic at dealer
Have problem with the choke. It has to stay in one place. Probably about half choke on the setting. This is where it will start and run.
No adjustment. Mechanic and me are baffled.
What is going on here?
Educate us.

casecollectorsc · Jul 26, 2017

Did you turn the load adjustment screw out a 1/4 turn more while it was running? That would give it more fuel. I assume you have a full stream of gas coming to the carb.

Greenfrog · Jul 26, 2017

Good idea. Yes good flow of gas. Thx.

tractorguy2 · Jul 26, 2017

Intake gasket or crack in manifold

dwag · Jul 27, 2017

Ran into same thing last year on same tractor.Spent way too much time but hated to give up. Problem was in upper half of carb, ended up replacing w/rebuilt. Warned supplier/re-builder when returning core $$$ and am sure someone will have same problem when carb goes out again.

Greenfrog · Jul 27, 2017

This D.C. Would always start with no choke. After rebuild, its operation is worse.
Mechanic is puzzled also. Only one "sweet spot" where it will start and run🤔🤔🙃😟😏☹️😬

Ron Sa · Jul 28, 2017

I have been around the block a few times with DC carb problems. Maybe I can help but need to know what "run" means. Will it only idle or will it also pull okay at various speeds and loads?

Grab the governor rod near the butterfly and yank the butterfly completely open FOR ONLY A SPLIT SECOND---SO THE ENGINE DOES NOT OVER-REV and tell me what the engine's response is. Is there black smoke out the exhaust? Does it sputter? etc.

Typically, half choke is nearly the same as no choke AT CRANKING SPEED because the choke opening allows air to freely flow with no vacuum at cranking speed. Half choke becomes effective at idle speed and higher because the air flow rate is then high enough to create a vacuum at the venturi. My DCs typically needed full-on choke to start when completely cooled down. If they start and run okay without choke when cool--- probably set too rich.

I can send a cross section of the carb and more detail after I know what "run" means.

dwag · Jul 28, 2017

This was a customers tractor. Never idled smooth but the more I worked on it, worse eng would run. Rather than soak, last attempt put upper half in sonic cleaner for day, that really aggravated the problem. Suspect housing was cracked internally perhaps at air/idle screw.

Greenfrog · Jul 28, 2017

Hey, thx for informative reply.....
Yes it will idle down and speed up and can drive around as usual. But Don't touch that choke button.!!!!
Will die if push down /no choke. And of course will die if pull out. For a long time it would start cold with NO choke.
I always felt that to be strange. Felt like carb needed makeover since had not been done for years and it sets a lot.

Greenfrog · Jul 28, 2017

Yes have it at county fair in antique tractor display. Adams co. Illlinois. Old time association.
Other guys there are puzzled at this also.

Greenfrog · Jul 28, 2017

Hope that defines"run".
I await your reply. Thx much

Ron Sa · Jul 29, 2017

I would disassemble and closely inspect every part and passage within the circle that I have drawn. These parts and passages are the power jet system.

My gut tells me something is wrong with C-66-22-1-65.

All four passages within the circle in the casting should be cleanable with a wire and blow gun.

Hope the pictures help.

Ron Sa · Jul 29, 2017

PS to pictures.

I think the ideal tool for removing carb jets is the impact screwdriver. It prevents possible damage to the jet's slot often caused by conventional screwdrivers and jet tightness.

The part I suspect as having a problem preferably needs a very small deep-well socket to remove and install. These are rare in my small socket sets. I carefully use a pair of small, long-nose vise grips on this hex.

Of course, I don't know what tools your mechanic has nor what all parts he removed in the rebuild. Good luck in finding the problem.

Greenfrog · Jul 29, 2017

Ran it n county fair parade today. Starts ok but choke has to stay in one place.
Also noticed that it won't idle down. Adjust screw not touching stop can't get it ti go closer and idle slower.
I am puzzled here.

kevinthefixer · Jul 30, 2017

While it's sitting idling, take a can of brake cleaner and start squirting a little bit at a time around the carb, intake manifold, etc., anywhere there might be a vacuum leak. If you find one the motor will rev even higher. Sometimes you can locate a leak very precisely, sometimes no.

Make over for the CASE DC carb.

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