Carb problems..... I think

[Rebuck33]

Hey fellows. I am getting close to a total tear down and rebuild/restore. Everything sandblasted and repainted, converted over to 12V, lots of new parts. So I finally got all the electrical done, except for the lights and I just couldn't wait for the lights to try to start it. I added the engine oil and hydraulic fluid and started cranking. Heck I was kind of happy that it cranked with all the work I have done but then I started getting greedy and wanted it to start. It wouldn't so I tried a little starter fluid to help me point to fuel or electrical. Started right up but wouldn't run. After about a 1/2 hour of screwing around, it only runs on about 90% full choke. Sounds good there, idles ok, throttles up ok, you just can't move the choke at all or it will shut off. After reading the posts which got me out of all the trouble in the past, it scares me cause everything is pointing to the metering jet. While rebuilding the carb, the kit I had didn't come with a metering jet, and I noticed the brass bolt was JBWelded on. When I turned it, I noticed it was broke in the middle where the larger holes are. I tried to clean it out by soaking and blowing it out. So are there any suggestions to try to clean it out? I'm afraid if I go after this busted metering jet, I will end up buying a new carb and with all the other money I pumped into this...... The wife is gonna kill me!!!!

I also looked all over the carb and cannot find a number to give to use fellows for help. Its a very simple carb and looks exactly like the one on the you tube video that shows how to clean the jet.

[Bob McCarty]

Does it look like all of the main jet comes out? It should be about 1 " long from the hex head to the end of the threads. Those can be purchased separately. Look on the flat part of the top half opposite the gas inlet. See if you can read all or part of a number. With that we can tell you what size main jet should be in there. When you were working on the carb, did you adjust the float height and drop? Did you clean or replace the screen in the gas inlet? Has the screen in the sediment bowl been cleaned or replaced. Those are the common causes of poor fuel flow. If the main jet is broken, they can be removed and the threads chased or helicoiled if stripped. Don't buy a new carb until you have a chance to answer a few questions and do some troubleshooting. 99% of the carbs can be repaired, some more easily than others though.

Bob

[Rebuck33]

Hey Bob... Thanks a bunch for taking the time to answer. THe main jet goes in a little, then has a few holes, then threads in. When it's taken out, only like one thread is left on and the rest remain in the body of the carb. I will look for the part number again. The carb and hydraulic pump were not painted, I sort of like the brushed look on them rather than painted so it may be easier to find now that I have it all cleaned up. I cleaned the gas inlet screen really good and checked the float while I had it apart. It looks like I have to bite the bullet and try to use an easy out or something on the remaining jet. I have NEVER had any luck with easy outs!!!! I will try and get the number and post it.

[Rebuck33]

I found a number. The last time I looked it was not there! The fellow I bought this from hand painted it with a brush about 4 times over it's life to any fine numbers like that were gone but now are back!. There are two sets of numbers, by the way this is a 1953 cub if it matters. The first set of numbers are 03 71. The second set of numbers are 251234R94. Any help on locating a new jet would be appreciated, then a prayer that I get the old one out also. Between posts I actually took it for a little ride, kind of fun. Seemed to lack power but I haven't messed with the top screw yet cause I haven't gotten the choke off yet. Me and the kids will be overjoyed if I am cultivating with this instead of hoeing this year.

[Bob McCarty]

Your carb should have a .034 main in it. You should spray/soak the broken end of the main jet for several days with a good penetrating oil. If you're not comfortable trying to remove the jet, you might want to send it to one of the carb guys on the forum. If it ends up needing to be drilled out and helicoiled, the hole in the body wall has to be enlarged for the helicoil tap to enter. It would be less likely to break an ez out in the brass, but will create bigger problems if that does happen.

Bob

[Don McCombs]

Did you prime the engine oil pump before you started it? Do you have oil pressure?

[Rebuck33]

also, when I look real close, the first number is a guess really can't tell if its 03 71? the 0 may not be correct. Maybe its even a 5 since its a 1953 but that is the only number I am not sure of.

[Rebuck33]

Hey Don, thanks for weighing in. I didn't prime anything other than cranking for a while and the oil pressure gauge seems fine, reading right in the middle when started.

Bob, where can I find an .034 main metering jet?

[bob in CT]

Here is one source, but I only see .030 and .035 jets with a quick check. http://www.mcdonaldcarb.com/category_s/359.htm

[Bob McCarty]

I have not found any aftermarket suppliers that have the exact size. However, there have been lots of kits installed with the .035 jet and I doubt that many, if any can tell a difference from the .034. Case/IH has them, but I don't think you'll want to pay the price. I'm not sure you understood my question on the float. Did you measure the height and drop of the float before putting the two halves back together again? If that is incorrect the needle may not open enough to allow adequate gas flow into the bowl.

Bob

[staninlowerAL]

Bob McCarty and Don McCombs, either one can rebuild your carb and make the necessary repairs if you don't feel confortable to do it. Both of these guys have fixed a carb for me including straightening the bowl and flatening the warped top. You can get more information by sending either of them a PM. There are others as well, I have just had them do one for me. Stan

[Rebuck33]

I ordered one a main jet. Thanks a lot. I will also double check the float travel again. When I checked it this morning I had gas leaking out the carb from somewhere. I didn't have time to check where it was coming from before work so I just turned off the gas. When I get it fixed, I will post what the problem was...... Or more questions to find a solution.

[Rebuck33]

Hey guys, so the new main jet is on its way and I just have no rest until this is fixed. I have a few different easy outs and have tried them. None worked. It just keeps removing more brass. I think if I screw with it much more I will be into the threads. I think I need to re-tap this. I have some standard taps, does anyone know what size the threads are? Also, does this require a special tap because the taps I have take two or three turns to start cutting and this looks like it needs threads all the way down to the bottom. Let me know what you think.

[Bob McCarty]

The main jet threads are 1/4-28 which takes a #3 drill bit. You'll want to drill by hand as the brass will pull in a drill bit in an electric drill faster than you can get your finger off the trigger. The jet inserts 3/4" so you can mark a bit with tape/etc to keep from going to deep. I'd start with a small bit, like 1/8" and gradually work up to the #3. When you reach that size, the tap should clean out the threads. If you have small left hand drill bits, start with them. Often the stub will unscrew and no tapping or chasing is then required.

Bob

Edit: I don't think you'll need a bottoming tap.

[Rebuck33]

Wow. I actually have 1/4-28. You guys have been awesome! I finally bit the bullet and just ordered a set of left handed drill bits. I could have used them about a hundred times throughout this rebuild. Just kept thinking I'm almost done now so I don't need them. Following this cub I have an M to redo so I got them. Hopefully I have better luck with them than the easy outs! I still think that is about the stupidest name in the world for them. All four of the small screws that hold the side plates onto the front steering housing were broken off. I got one screw out on each side and have an easy out stuck in one and a drill bit in another. After about 6 carbide bits and 2 diamond burrs, I gave up and decided a screw didn't have to be there again. Also broke a radiator bolt off but drilling there with a mag drill and retapping wasn't too bad. Thanks again Bob!