Couple of Farmall Super M mysteries

Farmall M, Super M, 400, 450 & 560 Tractors, 1939-1963

Moderator: Team Cub

Forum rules
Notice: For sale and wanted posts are not allowed in this forum. Please use our free classifieds or one of our site sponsors for your tractor and parts needs.
oldfarmkid
Cub Star
Cub Star
Posts: 71
Joined: Wed Dec 20, 2017 12:13 am
Zip Code: 29669

Couple of Farmall Super M mysteries

Postby oldfarmkid » Fri Jun 14, 2019 2:52 pm

Bought a 1952 Farmall Super M a couple months ago. It now runs very well,as a matter of fact, surprisingly, everything works. But since it's the only M I've worked on there are a couple of mysteries I need help solving. First, while adjusting valves verified it has a distillate head and that matches the vin# tag. The service manual states the pistons for Gas engines are aluminum, gray iron pistons for distillate. This engine has aluminum pistons. Seems this tractor has been worked hard over the years, was it common to install aluminum pistons when converting to gas. Or was it bored out and original iron pistons replaced with aluminum. Compression matches what new distillate engine would be. Second mystery may be connected to the first mystery. Service Manual states the carb part number for gas is 356 948 R92, part# for distillate is 357 231 R92. The carb brass tag on the carb installed on the tractor is part# 357 231 R91. Have not been able to find any info on what engine this carb matches. Thanks in advance for any info.

oldfarmkid
Cub Star
Cub Star
Posts: 71
Joined: Wed Dec 20, 2017 12:13 am
Zip Code: 29669

Re: Couple of Farmall Super M mysteries

Postby oldfarmkid » Fri Jun 14, 2019 8:47 pm

Managed to stumble onto the info on mystery carb. 357 231 R91 is for the Farmall 300 and 350 series tractors. They are 169 and 193 ci engines. With the Super M at 264 it's a bit undersized. It runs very well but the largest load I've put on it is while in road gear. Looks like I'm in the market for the correct carb.

oldfarmkid
Cub Star
Cub Star
Posts: 71
Joined: Wed Dec 20, 2017 12:13 am
Zip Code: 29669

Re: Couple of Farmall Super M mysteries

Postby oldfarmkid » Fri Jun 14, 2019 9:05 pm

Have been looking at prices for used carbs... rusted, muck covered, long neglected, GOLD. No longer chastising who ever installed what fit and got it running.

Jim Becker
Team Cub
Team Cub
Posts: 14426
Joined: Sun Feb 02, 2003 2:59 pm
Zip Code: 55319
Circle of Safety: Y
Location: MN

Re: Couple of Farmall Super M mysteries

Postby Jim Becker » Fri Jun 14, 2019 9:36 pm

357 231 R91 is the original carb for a distillate Super M. 357 231 R92 is an updated replacement. You probably have the original carburetor. The difference from the gasoline carburetor is the larger jets and a bowl drain cock in place of a plug. The mixture screws can be adjusted for running on gas. Distillate fuel was going away by 1952. First time the engine was worn out, it probably got new sleeves and pistons with higher compression to get more performance on gas. They might or might not have been larger bore than the originals.

oldfarmkid
Cub Star
Cub Star
Posts: 71
Joined: Wed Dec 20, 2017 12:13 am
Zip Code: 29669

Re: Couple of Farmall Super M mysteries

Postby oldfarmkid » Sat Jun 15, 2019 12:25 am

That explains why it runs so well with the carb thats on it. Also why the sweet spot on low idle adjustment was only about 1/2 turn ccw from closed and high idle adjustment about 3/4 turn from closed. Much less than my H. All your info will get transferred to the note book I'm compiling on it as I work through it.
Thanks Jim


  • Similar Topics
    Replies
    Views
    Last post

Return to “Farmall M, Super M, 400, 450, & 560”

Who is online

Users browsing this forum: No registered users and 0 guests