I have obtained a 24T2 Zenith, type F1372.The carb came off a running Seven as I understand it. Condition is excellent, virtually no wear and very clean. It differs from the one fitted to my AD Chummy (which works really well) in that it has an adjustable main jet (common on the tractor ones I believe) The main jet is stamped M 10 (1.0?) the adjuster has a fine thread & taper, so is it this that can adjust the diameter of the main jet down to 75 (which is the Austin Seven size)
It also has a useful bowl drain facility.
The Slow running jet is 45 (not a 50 as it is supposed to be), but this is not a real problem I hope.
More concerning is that there is no sign of an "Air Cap 150" ! what does this do? Is it necessary? Looking at specifications on 24T2 for other applications some do not have an "Air Cap" listed.
Choke is 14mm and a good fit.
Needle valve is 1.5 as it should be.
Burlen have surprisingly very few spares for this carburettor.
28-10-2020, 05:00 PM (This post was last modified: 28-10-2020, 05:12 PM by John3528.)
There's quite a good explanation of the 24T2 here: http://zenithcarb.co.uk/zen24/?___store=zenith. The section on the air jet includes, "In some instances, where the full value of the drilled hole is required for the ventilation of the main jet, an air jet is not used". This might explain the absence of an Air Cap 150.
As for spares, Gower and Lee (01923 247300) helped me out recently with bits for a 24T2.
POSTSCRIPT
Have a look also at www.villiersparts.co.uk, they have a page devoted to 24T2 spares.
28-10-2020, 06:57 PM (This post was last modified: 28-10-2020, 06:59 PM by Colin Morgan.)
A few years back, I ran my 1928 Chummy with a couple of different 24-T2 carburettor set-ups. The Austin carb spec I was trying to follow was Choke 14mm, Main 75, Slow 50, Air Bleed 150 (1.5mm) and Seat 2.0.
Both the carbs I tried had variable jets - and the needles were different - on the one with a turning knob of 0.56" diameter I found it needed 1.9 turns from closed, and the one with a turning knob of 3/4" needed one turn. On the final set up, the carburettor used had a 45 Slow running jet. I think the key parameter for success was the 14mm choke, which the F1372 will have.
That is interesting information.
I will try it without the air bleed for now- as I haven't one-!,the 45 sounds ok & as my main is 1 then my settings will be different I expect,
but yours will be a good start point.
Thanks
D
All cleaned up & ready to fit, BUT I have the problem of linking the accelerator shaft to the carburettor. Does anyone have dimensions/ shape of a link? Because of the location of the butterfly operating lever (relatively high) and the bottom of the accelerator shaft a bent link seems to be needed. ....not the same as to the original bronze carb.
I was faced with a similar problem and decided to replicate the bronze carb by making a whole new lever from brass plate, the same length as the lever on the bronze carb and with the slot orientated at the same angle. The original connecting rod would probably have worked but I chose to make a new link with a modern ball and socket to each end of a 5mm threaded rod to give me some adjustment.
My bronze 22FZ has a rod with right angle ends (3/16" dia or so) with holes each end to take a retaining split pin. Possibly this is BF31 (although mine was on arrival bent into an opened out "L"!!) The parts list under carburettor shows the strangler and it's wire links and the Control gear shows two rods:
BF31 Throttle valve control lever connecting link and BF13 Throttle control lever connecting link This is shorter and has a 90 degree bend one end and 135 degree the other. I haven't checked, but BF13 may be part of the hand throttle linkage.
I will check to see if the operating lever on the 24T2 is the same orientation as the 22FZ.... I imagine I can get male ball ends from somewhere, I do have an adjustable link with female ends that is about the right length...alternatively I sold a 1928 chummy AD locally (and am still on good terms with the buyer!) and it had a 24T carb, so i can go see what it has....if I'm quick before lockdown !
I don't know if Zenith sold a link with their Austin Seven conversion kit.
There are quite a number of new 24T around, but the problem I found when looking for one was that the 14mmChoke (which can be changed) and the jets are not remade by Burlen, although the adjustable main jet kit I think overcomes the lack of correct main jets.
Also the mounting flange holes are spaced differently. Caveat emptor!
This is the best picture I have of the throttle link I devised, taken during setting-up. Used a length of threaded bar get the distance exactly right, with ball connectors at each end, lock-nutted in place.
