Extreme Carb Problem Solution

Mon Feb 23, 2015 12:46 pm

Found this article in a publication called "Farm Show" that a friend of mine subscribes to.
Link to article: http://www.farmshow.com/a_article.php?submit_search=1&keywords1=Farmall%20Cub%20Runs%20Great%20on%20Chainsaw%20Carburetor&aid=24869&aid_next=23635&page_num=1&nav_previous=&nav_next=1

Here's the text;
Farmall Cub Runs Great On Chainsaw Carburetor

Paul Peyton didn’t want to spend the money for a new carburetor for his Farmall Cub tractor, so he used one off a Stihl chainsaw. The carburetor is bolted to a paper air filter element designed for a 12 hp Tecumseh engine, and to the tractor’s air intake manifold.
“As far as I know I’ve got the first Farmall Cub in the world with a chainsaw carburetor,” says Peyton. “I came up with the idea because the carburetors on Cub tractors are famous for being unreliable, leaking fuel, and starting hard. I had to rebuild the carburetor on my Cub 3 times over a 2-year period but it still didn’t run well,” says Peyton, of Huntsville, Mo. “I know people who have junked their Farmalls because they couldn’t make the carburetor work and couldn’t find a good replacement.
“I priced a newer replacement carburetor, but the $249 price tag encouraged me to seek alternatives. I’m a retired engineer and mechanic and have a lathe and a Bridgeport vertical milling machine, so I figured I could come up with something better. I decided to use a chainsaw carburetor because it develops a lot of power for a small engine, and because it’s designed in such a way that it can operate in any position. The Stihl carburetor’s bore is larger than the Cub’s, so I knew it would have adequate airflow.”
Peyton says his homemade carburetor has worked even better than he hoped. “The tractor now starts instantly, is more reliable, has more power, and doesn’t leak fuel. Also, it’s more fuel efficient because the Stihl carburetor does a better job of atomizing gas.”
The tractor’s original air filter was under the hood and the air intake above the hood. They were no longer needed so Peyton removed both of them.
The chainsaw carburetor originally was equipped with a built-in fuel pump connected to a small fuel line, with fuel pumped by pulses in pressure from the chainsaw’s crankcase. But on the tractor, the carburetor had to work with a gravity flow system, which required modifications. “The fuel pump side of the carburetor had to be altered, sealed and tapped so I could run a standard 1/4-in. fuel line and fuel filter to the tractor’s gas tank,” says Peyton.
He machined a new governor linkage bellcrank and pivot, as well as an adaptor plate and air filter mounting plate, which were machined from aluminum bar stock. The carburetor’s adjustment screws were shortened and re-slotted to allow for the bellcrank and governor link. Linkage from the bellcrank to the carburetor was fabricated, and the governor linkage was modified where it screws onto the carburetor.
“I wanted to use a modern paper filter and found one that was designed for a Tecumseh engine. But in order to make room for the air filter I had to shorten the tractor’s oil filter tube,” says Peyton. “I also had to discard the tractor’s large, breather-type oil filler cap. I fabricated an O-ring sealed oil filler plug with a folding handle and a dipstick that threads into the center of the plug.”
The tractor didn’t have a “breather” cap on the oil pan, so Peyton fabricated a positive crankcase type of vent system. A rubber hose allows blowby from the engine crankcase to vent into the carburetor’s intake airstream.
“The Cub’s original carburetor wasn’t adjustable, but the Stihl carburetor has 3 screw-type adjustments, one for high speed, one for low speed, and one for idle speed.”
Contact: FARM SHOW Followup, Paul Peyton, 4373 Hwy. D, Huntsville, Mo. 65259 (ph 660 998-4204; peyton.paul@gmail.com)

Not sure if Paul Peyton is on the forum or not. I sure would like to see the Cub Carburetor that came off this tractor to see how bad it was.

Peter
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Re: Extreme Carb Problem Solution

Mon Feb 23, 2015 1:17 pm

The air filter is in a poor location in my opinion. It is going to clog up with dust/grass clippings way too easy.

Re: Extreme Carb Problem Solution

Mon Feb 23, 2015 1:38 pm

I find it odd that he could come up with this solution, but couldn't rebuild a simple cub carburetor :-)

Re: Extreme Carb Problem Solution

Mon Feb 23, 2015 3:38 pm

Peter Person wrote:I sure would like to see the Cub Carburetor that came off this tractor to see how bad it was.

Or how bad the rebuilds were. Interesting article, but as most who attend Cub fests will agree, there are very few Cub carburetors that are permanently "unreliable, leaking fuel, and hard starting". It's a poor workman who blames his tools. Oddly enough, I have a fairly new Stihl chainsaw with a Stihl carburetor that doesn't start instantly every time. :shock:

Re: Extreme Carb Problem Solution

Mon Feb 23, 2015 4:06 pm

I bet I know someone who could rebuild the carb and it would last more than 2 years.

Re: Extreme Carb Problem Solution

Mon Feb 23, 2015 4:13 pm

Kudos to an interesting solution. Doesn't look great and I think that plastic fuel line may become problematic in the future. Glad it works and is more fuel efficient, but I think I'll stick with my self-rebuilt IH parts.

Re: Extreme Carb Problem Solution

Mon Feb 23, 2015 4:15 pm

Cecil wrote:I bet I know someone who could rebuild the carb and it would last more than 2 years.


I know a number of people...but I have not touched my carb since you and I worked on it in 2008!

Re: Extreme Carb Problem Solution

Mon Feb 23, 2015 4:57 pm

I get that magazine too, and I read that article, very interesting but it seemed like it took a lot of time and $ to modify like that, guess it was something he just wanted to do. I'm guilty of that myself sometimes :lol:
But as far as fuel economy.... I don't know how much better you can get than the stock carb?
Must be like mountain climbing, some people say why.....others say, why not! :thumbsup:
Bruce.

Re: Extreme Carb Problem Solution

Mon Feb 23, 2015 5:06 pm

The IH and Zenith carbs are the easiest to work on. I was a very young man when I started fixing carbs. Lawn mowers were first. If I didn't fix my go cart Clinton engine I didn't ride. Watch your float height and float drop. Set it to specs. There's a little round gasket under the needle valve that brings the fuel from the bowl to the venturing. The gasket is needed because the gas level is above these threads. If that little round gasket isn't used the carb can leak or run rich. A lot of times I see this gasket missing.
If your new to carburation go exactly by the instructions it's carb 101.

A chainsaw carb doesn't have enough venturing or gas flow for the c60 engine. When any engine doesn't get the proper fuel mixture it will eat metal. Burn valves, valve seats and pistols. Trust me the proper carb at around $200+ could save you money in the long run.

Re: Extreme Carb Problem Solution

Mon Feb 23, 2015 5:11 pm

It's probably not the carbs fault it's today's gas. It doesn't stay as fresh as gas once did. I use seafoam in everything. But my chainsaws. The husqvarna two stroke mix has a stabilizer in it. Two stroke mix lasts for 30 days. That's another post.

Re: Extreme Carb Problem Solution

Mon Feb 23, 2015 5:49 pm

I have looked at "Farm Show" a few times. I have found it to be a compendium of bad ideas and bad executions, often both in the same project.

Re: Extreme Carb Problem Solution

Mon Feb 23, 2015 7:38 pm

I had a cockshutt from the 40's with a big old oliver 6 cyl that run with a ski-doo carb.I was 18 or 19 and knew about snowmobles but couldn't understand a carb for such a small engine could furnish such a bull. it ran and pulled like it was factory.

Re: Extreme Carb Problem Solution

Mon Feb 23, 2015 7:53 pm

What about keeping it original?
The resale value goes down too.

Re: Extreme Carb Problem Solution

Mon Feb 23, 2015 9:49 pm

Do I remember correctly, didn't George Willer run a Cub on a Briggs and Stratton Carb at one time?

Re: Extreme Carb Problem Solution

Mon Feb 23, 2015 10:14 pm

tnestell wrote:Do I remember correctly, didn't George Willer run a Cub on a Briggs and Stratton Carb at one time?


Yes, he did, on Scruffy. The pictures are gone but there are several posts by George describing how he did it and the reason it worked. He even pulled in the Tug with it.
Sure do miss George.

Peter