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Collection, Preservation and Display of Old Lawn Mowers

Zenith carb - what is this part?

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I'm stripping my Zenith type 13 TCA-2 carb to give it a good clean up, however after looking at the parts diagram for it, i can't identify this part which I have arrowed - I'm thinking its perhaps an adjustment screw which has sheared off at some point in it's life? If someone could confirm please so I can try to source a replacement screw if this is the case

 

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wristpin Mon, 27/04/2020

No idea! Just looked at four carbs and none has it. Probably someone’s bodge to plug a hole, made for some unknown purpose?

hortimech Mon, 27/04/2020

Like Wristpin, I have never seen a carb with a bung like that. My only thought is that someone overtightened the main jet and snapped its end off, they then drilled a hole opposite the jet and using a fine punch, knocked the broken end out. They then blocked the hole they drilled (possibly with the old main jet). If the rest of the carb is in good order, I wouldn't bother about it, but seeing as you seem to be trying to get a museum quality machine, you will probably replace it laugh

wristpin Mon, 27/04/2020

Ha, you just beat me to it! After a “ ponder” while attacking an overgrown hedge I had a similar thought.      

If, when you come to adjust the main jet, it won’t settle, you will know that unseen damage to the needle seat was done. H’s suggestion re the nature of the plug may be spot on as I fancy the looking down the Venturi one can just see the end of a thread.

As an aside, I’ve never seen such bad pitting on the joint face of a Zenith carb bowl . A light rub over on the surface plate may be in order.

RedLeader Mon, 27/04/2020

Thanks both. I should have known it would be a bodge after everything else I've discovered so far on this mower. Oh well, I'll just have to see how it runs after a good clean. There seem to be a fair few of these carbs kicking around on auction sites if it won't run correctly. The ultrasonic tank has just arrived in the post so I'll get that up and running shortly!

RedLeader Wed, 29/04/2020

After a good clean in the US I can confirm the 'modification' is indeed a sheared off thread which seems to block the drilled hole pretty well, so hopefully won't cause any issues. Also, what looked like pitting on the bowl joining face looks to have been some sort of grey coloured 'stippled' grease which has cleaned off nicely.

The other question I have is that there appears to be a snapped off locating pin (top arrow) here, but if that's all it is/was, can anyone tell me what the small hole is beneath this is for? (bottom arrow)

wristpin Wed, 29/04/2020

No, I misled you there - either that or all of mine are snapped off! I think that its a manufacturer's blanking plug from when the gallery leading to that angled grilling was machined.

If you are using a new gasket it should not be necessary to use any sealant or "grey" grease of any description!!

RedLeader Sat, 09/05/2020

Thanks Angus, that's good news - one less thing broken/bodged on my carb! 

Next question - the parts diagram for the Zenith carb shows a 'washer for needle seating' - item 7 - with part number 08523

This is nowhere to be found on my carb - does this mean the float needle will not be able to fully reach all the way into the needle seat, as the seat will sit slightly higher up in the housing?

hortimech Sat, 09/05/2020

No, the float will just 'float' slightly higher smiley

It would be better if you could find a washer though, I seem to remember it is an alloy one.

RedLeader Sat, 09/05/2020

Thanks hortimech. Do you know if this washer would normally have been replaced when the carb was serviced? Just wondering if I can find a 'service kit' for the carb, or at least an old internet picture of a kit, to give me an idea of what sort of washer it is so I can try to find something suitable. 

hortimech Sat, 09/05/2020

I never replaced the washer when servicing a Suffolk engine, to be honest, it was very rare to remove the seat. I also do not remember a service kit for the carb, just the individual parts. This is not say there wasn't a kit, I just do not remember one.

Clive1962 Sat, 09/05/2020

Likewise, I have never changed a washer but have always thought I ought to have done in a rare seat change.... and out of shear curiosity, time on hands at keyboard, in these times, I set off with the part number and found this http://zenithcarb.co.uk/washer-27548.html ... gives a heads up to what is reqd.

 

 C.

RedLeader Sat, 09/05/2020

Thanks very much Clive, that's a massive help. Googling the part number didn't bring up any results when I looked, but obviously I didn't look properly! Now to organise a group buy to take the sting out of the postage cost (£6!!). I'll have a rummage to see if I can find something similar that would be suitable first though. Thanks again wink