Worn Throttle Body –Suffolk Mower’s Zenith 13 carb

[Ross365]

Many thanks to Richiew for his gift of the carb . It makes a stark comparison against the one I've been playing with; that one has something like 1mm of wobble on the throttle spindle whereas the one sent by Richiew has a small fraction of that - can hardly feel it.

I guess that the people who designed and made those carbs (at least 60 years ago?) did not expect that people would still be using them today .

 

[Ross365]

Just for anyone who is remotely interested , I've managed to take the flap off the throttle spindle on my worn carb. I soaked the screw in MEK for half and hour and it grudgingly came out, so I could get the spindle out. Attached is a picture of the carb body and the wear is visible - about the 10-11 o'clock position on the lever side. The "floating" end is not so bad.
The diameter of the replacement spindle I bought is 3/16". I guess it would be possible to make a brass bush, though it's going to be pretty thin. Not sure about allocating the time to do it - possibly a job for mid-winter?

 

[Melvyn Best]

Oillite bushes from a bearing supplier?

 

[Ross365]

Oillite bushes from a bearing supplier?

I had not realised you could buy such items off the shelf. Not familiar with those - will ask Mr Google . I tried one of the new spindles and that did not flap around as much as the old one, so the old spindle must be worn too.

P.S. Checked Oilite; think their smallest is too big, but this looks very interesting https://www.hendersonbearings.co.uk/03du03-bush-brand-neutral.html

 

[Melvyn Best]

https://www.ashleypower.co.uk/aic030504-imperial-plain-oilite-bush-316-x-516-x-14. Any good?

 

[Brad93]

I wouldn't bother with oilite. Oilite bushes work in situations where the rotating shaft generates enough heat to release the oil.

Just plain bronze or for that application even plain brass will work.

 

[Robotstar5]

Just looking through the restoration pics of my Suffolk, the footballer can't believe the quality of the repair

 

[Ross365]

https://www.ashleypower.co.uk/aic030504-imperial-plain-oilite-bush-316-x-516-x-14. Any good?

I'll keep a note of that, but that Henderson bearing is a split ring, and I'm guessing will be just a bit easier to fit?

 

[Melvyn Best]

I'll keep a note of that, but that Henderson bearing is a split ring, and I'm guessing will be just a bit easier to fit?

I wonder how tight the edges of the split would be after fitting? and also how tight the bush would be in the casing although I can’t see it moving .

 

[Ross365]

Yes, I think it would be a trial and error job, so I might have sacrifice one (or two) to get it right

 

[Ross365]

Well it's taken a while, but here is my Zenith 13 carb, now fitted with a bush on the throttle spindle (compare with post 22).
The bush used is as per the link in post 24. Did a vary simple job; just drilled it out with a 1/4" cobalt drill, smoothed it off with some wet & dry, then drifted the bearing in.

It's not exactly a Swiss watch, but definitely less play and should keep it good for the future.

 

[Ali]

Good stuff. Fond memories of cutting the lawn with these Suffolk cylinder mowers as a kid. We had a Punch with no clutch, drove it into a pond once. The little Colts were a bit more user friendly. I’ll get another one when the kids grow up and stop wrecking the lawn or perhaps an Atco with a kick start, like my Grandfather’s. Two a penny these days.

 

[Ross365]

I’ll get another one when the kids grow up and stop wrecking the lawn or perhaps an Atco with a kick start, like my Grandfather’s. Two a penny these days.

Not sure about "two a penny". Machines in good running order are still in demand and fetch fair price. Spares for these old machines can be found, but prices are rising. Coil failure on the magneto is fairly common and second hand one now will currently cost you £40-45. Cutting cylinders in good shape are likewise getting harder to find. Running an old Suffolk is a bit of a hobby, but when they are in good fettle, they do a very good job.

 

[philipcswift]

I am a huge fan of the old Suffolk Punch / Colt mowers. Many use the Zenith 13 carbs, which are now 50-60 years old and show appreciable wear where the throttle spindle enters the body.
For ~£40, Caswell, sells an electroless nickel plating solution. If it’s as good as the electroless nickel stuff I used in the 1980’s, that might offer an way of building up the spindle to a good diameter? (recent experience with an ordinary Ni plating solution was poor).

Easier and cheaper, but shorter lasting, maybe a few turns of PTFE tape might help?

To get the spindle out, the small screw which holds the throttle flap in place on the spindle needs removing and I’m guessing that has locking compound on it; guess that needs heating up with a solder iron(?) to loosen?

Any thoughts?

Part number 013624 Buy one of these.

 

[dave h 2]

With respect it's the carb body that wears