Zenith 24T-2 Carb on a Petter A1

I have just stripped down the Zenith 24T-2 Carb on my Petter A1 engine for cleaning, inspection and fitting of a new (plastic) float.

However, I have noticed that there is no air regulating screw on this particular carb and there is no air jet fitted - just the slow running jet.

Should there be an air jet fitted if there is no air regulating screw?

Any help or advice would be much appreciated.

I found this video useful as a beginner and all four of my carbs are like this

After a bit of research I am going to answer my own question!!

I spoke to the guys at Burlen Ltd (who supplied me with the gasket pack and float kit) were very helpful and sent me a Zenith Spare Parts Schedule for Petter Industrial Engines (Sheet Ref: SL.237).

This has a table listing the Petter Engine Model, Year, Zenith Reference Number, Choke Tube Size, Main Jet Size, Air Jet Size (if fitted), Slow Running Jet Size and Needle Seating Size.

The Zenith Reference Number is stamped on the fuel inlet boss - mine was C.1048 which seems to be older than 1950 to 1951 as the reference numbers in the table start at C1221 for the 1950 to 1951 date range.

For nearly all the Petter engines listed in this table there was no air jet fitted (table states 'Nil'). The guys at Burlen Ltd confirmed that if no air jet was fitted the air regulating screw would not have been needed.

If anyone is interested in a copy of this information please send me your email address in a PM.