The Old Lawnmower Club
Collection, Preservation and Display of Old Lawn Mowers

Qualcast 35S carburettor info required

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HighlandSam

Hi All,

Thanks for letting me join, this site has a wealth of information.

I have searched the forum but cannot see any posts which answer my questions.

I purchased a 35S last year and have only had it running twice. I have replaced the head gasket, various seals and the fuel line and cleaned the carb but it still won’t run correctly. I downloaded the user manual, but the carb identified in the manual doesn’t appear to match the carb on my mower. Can anyone assist from the pictures?

It will start on full choke and run, when you take the choke of it stops. Even if i leave it on full choke it cuts out as soon as you engage the blades.

Appreciate any help identifying the carb so i could replace.

Forums

Henno Tue, 08/07/2025

Hi Sam,

It is a TIlletson carburetor. I have some documentation on it, a pdf somewhere. 
I will look it up in the evening.

The behaviour your are describing is from petrol gunk in the ports of the carb. It is not clean. You could try this with a carburetor cleaner spray and leave it overnight to redo the next day of to clean it in a ultrasonic tank.
 

Regards, Henno

Colin43 Wed, 09/07/2025

That looks nothing like the carb on my two examples of this mower.

I did however experience similar issues with my mower when it first came to be used earlier this year. A full carb clean did not resolve the issue, but eventually a process of trial and error it came to light that the mixture control screw ( the main Jet at the bottom of the float bowl) was screwed well in, too far. Adjusting that took about a minute and it now runs sweet as a nut.

Colin

 

HighlandSam Fri, 18/07/2025

Hi Henno,

Thank you very much for solving the carb manufacturer, I’ve been looking for ages. I replaced the float and bowl last year but will look to carry out some further cleaning. I thought in my original post i had posted more photos!!

 

HighlandSam Fri, 18/07/2025

Hi Colin,

 

Thanks for the info, i will be removing the carb tomorrow and giving it a good clean. Will update with my findings.