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throttle surges
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- Posts: 44
- Joined: Fri Jan 13, 2023 9:58 pm
- Zip Code: 49401
throttle surges
My 52 cub was rebuilt in 2022. It is bored .20 over with high dome pistons and the crank is .10 under. The tractor runs great until about half throttle then it starts to surge. When under load I can very slowly increase throttle. If I get into a heaver spot where the governor needs to increase fuel it starts surging again and won't stop until I move the throttle back to half. I have checked the float and it is set right. Is there anything that it could be other than the gov spring or worn parts in the gov? I'm a little hesitant to pull the gov off sense I've never seen it done before and I don't want to mess it up. We have been considering going to the Barnyard Bash this year if I don't figure this out before then.
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- Team Cub
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Re: throttle surges
The surging is likely something that can be corrected with adjustments. First adjust the linkage from the governor to the carburetor. Engine off, pull the pin from that link. Push the speed control lever fully forward. Hold the carburetor throttle fully open. Adjust the length of the rod so the pin just slides back in without moving the other parts.
If it still surges, look on the front side of the governor to locate the governor bumper spring holder. It will be held with a jam nut. Loosen the jam nut and turn the holder in some to eliminate the surging. If turning it several turns has no effect, unscrew it completely and clean/inspect the spring. Try again. If the spring is rusty/broken you need a new one.
If it still surges, look on the front side of the governor to locate the governor bumper spring holder. It will be held with a jam nut. Loosen the jam nut and turn the holder in some to eliminate the surging. If turning it several turns has no effect, unscrew it completely and clean/inspect the spring. Try again. If the spring is rusty/broken you need a new one.
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- 5+ Years
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- Joined: Wed Jul 08, 2015 10:24 am
- Zip Code: 19342
- Tractors Owned: 1948 6v - Dozer
1949 with kub klipper belly mower. mag 6v - Mom
1950 with plow, 54 blade, mott mag 6v - Roxanne
1953 54 blade, c22, wood 42 6v
1957 6v - barn Queen
1965 lo-boy with c-3 mower 12 v - Loboy
1974 Horse II 12 v c-2
1975 with woods 42-6 12 v - Horse
1979 long strip 12 v stuck engine
130 with international 1000 loader 6 v
1969 140 with bush hog tow behind mower 12 v
Terramite T-6 4WD Backhoe Perkins diesel
Memberships: Rough and Tumble Engineers Historical Association;Chapter 8 IH Collectors; IH Collectors Worldwide - Circle of Safety: Y
- Location: Glen Mills PA
Re: throttle surges
The first thing is what Jim said. I would also look for air leaks at the carb/ manifold gasket.
What carb are you using? The 52 would have had an IH carb. With the work done did you also convert to a Zeinth carb? Some members have posted about fit issues on the older manifolds and the Zeinth and suggest using 2 gaskets to get a good seal.
Some members suggest spraying WD-40 or starting fluid at the gasket area with the engine running and listening if the RPMs change. If so there is a leak somewhere.
What carb are you using? The 52 would have had an IH carb. With the work done did you also convert to a Zeinth carb? Some members have posted about fit issues on the older manifolds and the Zeinth and suggest using 2 gaskets to get a good seal.
Some members suggest spraying WD-40 or starting fluid at the gasket area with the engine running and listening if the RPMs change. If so there is a leak somewhere.
When you only have 9 horsepower you need to know the names of all of the ponies!
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53 Cockshutt 20 restored (Shooter)
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Re: throttle surges
Years ago, when I had my 1st Cub, I rebuilt the engine, much the same as yours. After the rebuild, it always ran a little lean. With the increase in compression, it wanted a touch more fuel. Along with the basic adjustments Jim mentioned, you might consider switching to the next size main jet. A lean fuel / air mixture will absolutely cause surging.
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- Posts: 44
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Re: throttle surges
I'm sure the tractor was all original when I bought it. From the IH carb to the 6 volt to the seat that is in far better than average condition for its age. (It still has 90% of the cloth and padding.)
I had already tried the bumper spring. It didn't help at all. I have also adjusted the linkage between the gov. and carb. by the book. I think I will order a new larger main jet if i don't find an air leak.
It seems a little strange that higher compression would need a bigger jet but I guess high dome pistons means less air fuel mixture going into the cylinder.
I had already tried the bumper spring. It didn't help at all. I have also adjusted the linkage between the gov. and carb. by the book. I think I will order a new larger main jet if i don't find an air leak.
It seems a little strange that higher compression would need a bigger jet but I guess high dome pistons means less air fuel mixture going into the cylinder.
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- 5+ Years
- Posts: 2837
- Joined: Wed Jul 08, 2015 10:24 am
- Zip Code: 19342
- Tractors Owned: 1948 6v - Dozer
1949 with kub klipper belly mower. mag 6v - Mom
1950 with plow, 54 blade, mott mag 6v - Roxanne
1953 54 blade, c22, wood 42 6v
1957 6v - barn Queen
1965 lo-boy with c-3 mower 12 v - Loboy
1974 Horse II 12 v c-2
1975 with woods 42-6 12 v - Horse
1979 long strip 12 v stuck engine
130 with international 1000 loader 6 v
1969 140 with bush hog tow behind mower 12 v
Terramite T-6 4WD Backhoe Perkins diesel
Memberships: Rough and Tumble Engineers Historical Association;Chapter 8 IH Collectors; IH Collectors Worldwide - Circle of Safety: Y
- Location: Glen Mills PA
Re: throttle surges
An air leak at the carb /manifold gasket will also create a lean mixture.
If it was my cub I would try replacing that gasket first.
If it was my cub I would try replacing that gasket first.
When you only have 9 horsepower you need to know the names of all of the ponies!
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- 10+ Years
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- Tractors Owned: 1956 Farmall Cub with Fast Hitch, F-11 plow, Disc, Cultivator, Cub-22 mower
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Re: throttle surges
Hi,
I sent you a PM, you get to it at the top of the page.
I sent you a PM, you get to it at the top of the page.
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Re: throttle surges
52DAVE wrote:We have been considering going to the Barnyard Bash this year if I don't figure this out before then.
Dave, whether or not you figure it out, come on down to the Bash. You will be glad you did.
There are two ways to get enough Cubs. One is to continue to accumulate more and more. The other is to desire less.
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- Posts: 44
- Joined: Fri Jan 13, 2023 9:58 pm
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Re: throttle surges
I want to come to the Bash if We can. The weekend before the Bash is the Holland Vintage Car Club show and cruse on Friday and the West Mi. Mustang Club meet on Saturday. I will be at both of those if the weather is nice. We will have to see how a few other things go this spring.
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- Team Cub
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Re: throttle surges
52DAVE wrote:. . . I had already tried the bumper spring. It didn't help at all. . . .
If all the other suggestions fail to fix it, turn the bumper spring in a little more.
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- Posts: 44
- Joined: Fri Jan 13, 2023 9:58 pm
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Re: throttle surges
Well it's definitely not running lean. I was dragging for about an hour with it Monday when it started to miss. I went back to my shop and checked the spark plugs after it cooled down. They were coal black as is the inside of the muffler. I cleaned them and checked the gap turned the idle screw in 1/2 turn. Tuesday it surged less when I dragged for about an hour and then it started missing again. I'm guessing the problem is a piece of carbon in one of the plugs. Sense then the weather has been too wet and cold to try again. I will have to play with the idle adjustment to get it set right when the weather improves.
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- Team Cub Mentor
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Re: throttle surges
Double check, then triple check the ignition system.
I'd also compression test the engine and valve tappet adjustment.
I'd also compression test the engine and valve tappet adjustment.
I have an excuse. CRS.
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- 5+ Years
- Posts: 2837
- Joined: Wed Jul 08, 2015 10:24 am
- Zip Code: 19342
- Tractors Owned: 1948 6v - Dozer
1949 with kub klipper belly mower. mag 6v - Mom
1950 with plow, 54 blade, mott mag 6v - Roxanne
1953 54 blade, c22, wood 42 6v
1957 6v - barn Queen
1965 lo-boy with c-3 mower 12 v - Loboy
1974 Horse II 12 v c-2
1975 with woods 42-6 12 v - Horse
1979 long strip 12 v stuck engine
130 with international 1000 loader 6 v
1969 140 with bush hog tow behind mower 12 v
Terramite T-6 4WD Backhoe Perkins diesel
Memberships: Rough and Tumble Engineers Historical Association;Chapter 8 IH Collectors; IH Collectors Worldwide - Circle of Safety: Y
- Location: Glen Mills PA
Re: throttle surges
52DAVE wrote: Tuesday it surged less when I dragged for about an hour and then it started missing again.
I still think if it happens after an hour that it could be an air gap developing between the carb and the manifold.
When you only have 9 horsepower you need to know the names of all of the ponies!
-
- Team Cub Mentor
- Posts: 5654
- Joined: Thu Aug 03, 2006 6:20 am
- Zip Code: 43358
- Tractors Owned: 48 Cub Diesel (Cubota)
53 Cockshutt 20 restored (Shooter)
52 Cockshutt 20 unrestored
47 Leader "B" (Herckie)
49 Leader "D" (Princess)
49 Leader "D" very rough
48 Leader "D" unrestored
Kubota B6200E
Kubota B6200HST
Kubota B8200HST-D - Circle of Safety: Y
- Location: OH West Mansfield
Re: throttle surges
On the idle screw, in is richer, out is leaner, in case you were not aware.
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