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A Question for Mr. Rustyfarmall/M Carb Rebuild

C

Coax

Member
I'm in the process of rebuilding another E-12 M Carburetor and everything was going smoothly, coming out of the Cleaner bath and I noticed that the idle metering jet had snapped off.I'm afraid to ask, But am I screwed before I even get started???Is it possible to get that stub out and retap it or toss in the towel now? Any ideas before I go walk off a bridge ? :x :cry: :oops:
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You can get them out, make a tiny easy out for starters. You can purchase a tap to restore threads if you boooger them. I'm thinking it is a number 4 but you will have to determine that. New jets are available, but there are several different sizes , all with same part number except the designation like 72 74 75 etc so get correct one.
 
I had the same problem with the idle jet on an H. The first thing to do is put a small braze tip on your torch and heat just the brass jet part broken off in the threaded hole. Don't get it hot enough to melt. Allow it to cool completely. If you find an EZ-Out or left-hand drill as mentioned, use it to remove the stub. Short of that, drill then re-tap with, I believe, a 5-40 tap. Please verify this size with the jet that comes in your kit as it was more than a few years ago this happened to me.
 
A small E-Z out or you can also use a small flat blade screw driver and drive it in, make sure it is not wider then the treads in that area. Then twist it back out. BTDT on carbs and didn't have a small enough E-Z. out but did have the screw driver. You can clamp a vise grips to the screw driver if you need more twist power
 
Drill carefully & re-tap with a 5-40 tap. Your local gunsmith can assist you if you cannot find the correct tap. I bought my own several years ago after an "experience" lesson.
The jet is available at your IH dealer.
 
Thanks to all, Went to local has- it- all shop and got me a couple left hand drill bits to start,and I'll add some heat to the equation...And alot of Kroil. You are all scholars and gentlemen!!! :D
 
Well, got home w/my tools of destruction and heated the core up good and hosed it down with Kroil and waited until cool. Then I put the tiny lft handed drill bit into a Palm chuck instead of a drill for better control. And no luck! It just reamed out the stub. I made sure I used much smaller bits so most of the material is almost gone.those threads are cemented in there. So...Y'all say to use a #5-40 tap on the existing threads or is that going to hog it out to a larger size???I not doubting your advice just want to double check my Data b/4 I go buy the tap....Thanks for the patience.

Peace :roll:
 
(quoted from post at 21:59:14 05/10/10) I'm in the process of rebuilding another E-12 M Carburetor and everything was going smoothly, coming out of the Cleaner bath and I noticed that the idle metering jet had snapped off.I'm afraid to ask, But am I screwed before I even get started???Is it possible to get that stub out and retap it or toss in the towel now? Any ideas before I go walk off a bridge ? :x :cry: :oops:
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Drill it out with a #40 drill, and then re-thread using a #4-40 tap.
Do not use your electric drill. Put the drill bit in a hand held chuck so that you can "feel" if the drill is going straight.
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Thanks Rusty, I wanted to make sure on the tap size. 5-40 was not standard and I couldn't tell what size the original was without damaging something. So the NEW jet will be #4-40??? The thing is so tiny, I could'nt tell if it was fine or coarse thread.
 
(quoted from post at 10:37:22 05/12/10) Thanks Rusty, I wanted to make sure on the tap size. 5-40 was not standard and I couldn't tell what size the original was without damaging something. So the NEW jet will be #4-40??? The thing is so tiny, I could'nt tell if it was fine or coarse thread.
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It is neither fine thread nor course. It is 40 threads per inch.
 
Duh, sorry about that. I realised that after I reread the Post...... Just so I'm Clear.. The threads on the jet are 4-40????Not 5-40.
 

The easiest way to know for sure is to "mesh" the threads of the new idle jet with the threads of the cutting tap. If the threads are not a perfect match, you have the wrong tap. Just a word of caution, those tiny little threading taps are brittle, and snap off very easily, leaving the broken part stuck in the hole.
 
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