Carb size

[grinchsr 642]

I was told that the M12 - M14 - and M16 all took the same carb but I was also told that they Do not.   Can anyone verify this for me.  I have a M16 with a bad carb but I have a M12 spare carb that I can use

[wallfish 17,587]

I think it's more like the 10 and 12 can use the same carb, and the 14 and 16 can use the same one, but I doubt a 12 and 16 use the same carb.

Probably best to check the Kohler Magnum manual. It's in the Manuals section.

[Racinbob 11,788]

I've wondered the same thing about the K series. Apparently the same carb will work for a K-91 through a K-181. No difference internally?

[wallfish 17,587]

 Never really spent much time on this with carb numbers and all, but I have taken a carb off an 8hp and put it on a K91. My philosophy at the time was the fuel mixture can just be adjusted to match the lower HP engine. It worked fine. (probably because it's the same exact carb -- LoL)

There are size numbers if you look inside the carb above the choke plate at about the 2:00 position.

Also used Clinton carbs on Tecumseh engines. That's one way to eliminate the crappy Tecumseh carb issue.

 

Maybe someone with real experience can get all of us straight on this.

Edited August 28, 2016 by wallfish

[Anglo Traction 761]

'M' Series engines may have fixed main jets fitted and either Kohler or Walbro of which I tend to avoid and no nothing about.

 

From what I've established by comparing all 'K' and 'M' series Carb part numbers, 10/12hp use one size of Carb/Jet combination and 14/16hp use another.

Even the Repair Kit part numbers are different. The 14/16hp Kit (25 757 02 s) has a larger hole in the Float Valve Housing (may be the only difference).

This tells me that if you put a 10/12hp Carb with smaller valve and Jet on a 16hp Engine, you will run into possible issues of running 'Lean' and subsequently Hotter.

If you (can) change the Main Jet and Float Valve seat for the correct ones, it may be possible to use it on 16hp, but then the Venturi size may affect performance as well?.

To be sure, I would always swap 'Like for Like' unless Tuning up for Non Standard running. 

Regards. 

     

[slammer302 2,156]

10-12 used a #26 carb sum of the early 14 had a #28 but most later shared the #30 that the 16 used. K91 did use a smaller venturi carb but one from a 8hp will work.

[grinchsr 642]

I love to hear from the experts.  You guys have all the answers.   THANKS

[tbarnhart 240]

I don't know about the newer walbro carbs on the Magnum engines, but the older big block K-series used three different sizes of carbs as slammer stated above. The outside of the carb looks exactly the same, but the size of the venturi is different to allow for different airflow levels. the number is found inside the carb throat on the choke side cast into the carb. As far as I know, the numbers stand for the nominal diameter of the venturi (not the throttle plate) in 32nds of an inch. A 26 was used on the 10-12 hp and will measure 13/16 and a 30 was used on the 14-16 hp and will measure about 15/16. The jetting may be a bit different to accommodate the different airflow potential, but the carbs will work and tune properly on different sizes of engines. The smaller carb may limit the hp of a bigger engine, and a big carb will tend to make a smaller engine lag on acceleration. I'm guessing the newer engines used several different sizes of carbs as well, but I've never looked into it. FWIW, my Tecumseh OH160 engine on my C-160 has a 1in. venturi carb. Tecumseh must have thought that the OHV engine needed to breathe.