M idle metering jet

JDnTN · Jan 22, 2012

I opened the carb on a 1950 M I just bought and one of the "sides" on the end of the jet is gone. I got it out with a pair of pliers. Will this jet have to be replaced or is it usable? I found one online but it was for use with the "fire crater pistons", so I assume it would not work. Thanks for any ideas. Jon

FC Andy · Jan 22, 2012

Jon, I broke one of those Ears off once- I then broke off the other to keep airflow equal. I then ordered a new jet from my Case IH dealer to replace it at my leisure. I ran it that way for a while- with the broken screwdriver tabs- never had a lick of problems. I would add- I don't know what difference fire crater pistons would make to the idle jet- if you buy that jet, it should work just fine. -Andy

pete 23 · Jan 22, 2012

It will work fine with or with out ears on it, just has to be screwed in nice and tight but not over tight. The difference in the jet for fire crater pistons would be the hole size. There are about four different ones used in the m's . They are numbered,70 72 74 75 which correlates to wire gauge drill sizes. You will notice the hole is very small, about .020 so the difference between them is very little. Some engines you will notice a difference some you will not. In fact, we got a new 656 in years ago and it did not idle nice and I found it had the wrong idle jet, correct one made the difference. Also, if there is enough room over the top of the metered hole size you can cut new slots , have done that a few times, just don't damage the hole size. I have a carb laying out in my garage now with the jet broken off down inside for a super H and I have a tap to go down in there and redo the threads. Kind of tricky but usually works out ok. Will have to get a new jet for that one.

M idle metering jet

JDnTN

Member

FC Andy

Member

pete 23

Well-known Member

Similar threads