IH carb for 1952 Cub

[Johnnyputt]

I finished the restoration of my 1952 Cub and having issues with IH carb. Have two carbs that are identical and can't make one good one from the two. (On one the top half has stripped out threads for fuel inlet.) It'll idle just fine but when you give it throttle, it'll act like it's starving for fuel. It'll run ok with choke closed a little. I've replaced everything in it. All the passages are open. I even soaked in mean green and boiled it on the stove. It's driving me nuts. I need to send it off to have it made right. Where can I send it?
Thanks,
Johnny

[Bob McCarty]

Make sure you have good fuel flow to the carb. Remove the main jet (brass hex screw on the side), turn on the gas and catch it in a clean container. You should have a good steady flow. Let it flow for at least a minute and make sure the flow doesn't decrease. If it does you may have blockage upstream (sediment bowl, or debris in the tank). Did you adjust the float when it was apart?

[wrz]

One other place to check is the inlet screen behind where the fuel line enters the top of the carb. On My 47 it was so bad it had to be replaced.
Wm

[Johnnyputt]

Yes, I checked the screen inlet, it's fine. I did adjust the float. I'll do the test with removing the main jet and get back to you. Thanks for the reply.
I have a stream coming from main jet.

[NJ Farmer]

Check the main jet and make sure it’s not blocked.

NJ Farmer

[Crimson Tim]

That it runs better with choke is an indicator that it is running too lean.
As mentioned, check fuel flow. And yes, Bob does mean literally at least a minute. If there’s a partial fuel blockage at the sediment bowl, for example, it will take a while to see the fuel stream diminished.

Do you have any rust or other debris in the tank? If so, I would place my bets there and clean the entire fuel line again. It doesn’t take much junk to slow the flow.

Another thing that can happen to lean it out is have an air leak. Is your carb top in need of flattening? If you have it drawing air in there or where the carb mounts to the manifold, it will also lean out the mixture. If you spray a little carb cleaner in that vicinity, and it momentarily runs better, then you’re probably leaking air.

One last thing, double check that the choke butterfly is operating correctly. The linkage can get hooked up wrong so it is closed when the lever shows it should be open and vice versa.

[SamsFarm]

If your fuel flow to the carb is slow, it would not hurt to remove the steel line and blow the line out with compressed air!

[Johnnyputt]

Fuel tank is crystal clean. I have a new fuel line. I put a gallon and a half in tank and took out main jet. Took approximately 30 minutes for it to drain thru main jet hole. It didn't pour out the hole but rather dribbled down the carb and dropped off the bottom plug on outside. I put a carb off a working cub it it ran perfectly. Something in this carb is off and I can't figure it out. I tried to post a picture of the stream coming out of the main jet but I haven't figured that out yet.

[indy61]

I put a gallon and a half in tank and took out main jet. Took approximately 30 minutes for it to drain thru main jet hole. It didn't pour out the hole but rather dribbled down the carb and dropped off the bottom plug on outside.

That seems way too long. Check for blockage in tank where the sediment bowl screws in.

[Bob McCarty]

The only thing between the gas inlet and the jet is the needle valve and seat. It may have debris under the seat, or the float may be incorrectly adjusted. What settings did you use for the float adjustment?

[staninlowerAL]

....... I need to send it off to have it made right. Where can I send it? Thanks, Johnny

JMHO, Bob McCarty is probably too modest to say so but if it can be fixed, Bob can fix it to include fixing a warped top and the threads on the inlet. If you get him to do it you won't be sorry. Good Luck, Stan

[Johnnyputt]

What settings did you use for the float adjustment? With the carb upside down, I have bottom of float at 1.4" from bottom of top half of carb with no gasket installed. I have the original needle seat with no plastic tip. I'm going to put a new one in and see if that makes a difference. I don't think there's a restriction in the fuel from tank to carb as I've had another carb off a cub and it ran fine. There's something I'm over looking and it's making me feel old. Ha. Thanks for the replies and help.

[Bob McCarty]

You set the float height (1.4"), but did you also set the float drop (1.6")? I prefer the steel needle over the viton tipped needles as a lot of them tend to stick or not seal.

[Johnnyputt]

Bob McCarty, Yes, the height is at 1.4 and drop is at 1.6. You were mentioned as the guy to send this carb to and that you could fix threads on the fuel inlet. Are you able to take a look at this, and if so, how do I get this to you?

[Bob McCarty]

PM sent.