Monobloc Jet Size?

[Colin Sparrow]

A member had asked for advice as to what main jet size to use in an Amal Monobloc fitted to a 32A with a square barrel.

He thinks the stamping on the jet is 222 or 322.

The Archive Amal data is locked away in storage.

Any ideas so I can advise him?

[Brian Thompson]

A member had asked for advice as to what main jet size to use in an Amal Monobloc fitted to a 32A with a square barrel.

He thinks the stamping on the jet is 222 or 322.

The Archive Amal data is locked away in storage.

Any ideas so I can advise him?

I've had a quick browse through the 'Greeves' book (Carrick and Walker) carb specs, and it's hard to pin down without a bit more info. Anyway Colin, I thought you could pass this on to the member if it's of any help. I thought this might be a good post for the forum, and of course can be edited/added to over time.


Assuming it's for a TES/TFS (32A, 'square' and 'challenger' barrel respectively) it should have a Villiers carb (S25/5 and S25/6 respectively, both with 140 main jet) according to the data.

Other listings for Monoblocks (both 376 and 389 series) used with 'Greeves' barrels are as follows;

34A (246cc) Villiers engines (Greeves 'square' barrel?)=
24MCS > 389, 1 3/16", 380 main jet.
24MDS > 389, 1 3/16", 380 main jet.

37A (246cc) Villiers engines (Greeves 'challenger' barrel?)=
24TGS > 376, 1 1/16", 190 main jet.
(THS/TJS used 626 series, both with 140 main jets.)

Greeves engines (246cc) with 'challenger' barrels=
24MX1 > 389, 1 3/16", 350 main jet.
24MX2 > 389, 1 3/16", 350 main jet.
24MX3 > 389, 1 3/16", 350 main jet.

For further info, 9E (197cc) 'iron' barrel Villiers engines with Monoblock carb as follows;
20SA > 376, 1 1/16", 290 main jet.
20SAS > 376, 1 1/16", 250 main jet.
SCS > 389, 1 3/16", 460 main jet.

Also for further info, other Greeves Amal applications as follows;
THS/TJS used 626 series, both with 140 main jets.
24MX4/36MX4 used 932 series with 300 main jet.
24MX5 used 930 series with 280 main jet.
25D/25R (Anzani engines) used 375 series, 25/32" with 130 main jet.
32D (Anzani engine) used 376 series, 1.0" with 260 main jet.
250 Griffons used 930 series (280 main jet) and 932 series (310 main jet.)
380 Griffon used 932 series (300 main jet.)
380 Griffon QUB used 1034 series (320 main jet.)
24RAS Silverstone (36A Villiers engine with Greeves 'square' barrel) used 5GP2 series, 1 3/8" (390/420 main jet.)
24RBS/24RCS/24RDS/24RES Silverstones (Greeves engines) used 5GP2 series, 1 3/8" (400/420 main jet.)
35RFS Oulton (Greeves engine) used 3GP2 series, 1 1/2" (530 main jet.)

Amal (in the UK, The Amal Carburettor Company) have an excellent website with lots of useful information and are well worth checking out. They can be contacted at; www.amalcarb.co.uk (telephone; 01722 412500) They have a comprehensive listing of Amal carb applications for a huge range of Greeves models, as well as spares, repair/overhaul kits, set-up guides and lots more.

Click onto 'product search' on the website homepage (right at the top), type in 'monoblock carbs' into the 'search term' field, select 'Greeves' from the drop-down 'vehicle manufacturers' menu (it will then load the listing automatically), then go to the 'vehicle model' drop-down menu below that and click onto the small black arrow for the full listings of what they offer for Greeves models. Their prices are pretty reasonable too, e.g. £126 for a brand new Monobloc to fit an MDS. Sounds tempting to me, and avoids all the hassles with trying to fettle/set-up old worn out carbs and re-sleeving bodies etc etc!

Incidently, having this done to a Villiers carb costs around £60, the chap who does it can be contactacted at 01332 883130. This includes a 're-bore' and a new brass slide fitted. He also does Villiers 9E clutch conversions for 8E Albion gearboxes for £120, all parts inc. I spotted this recently in a private ad in 'OBM' but don't know any more. Presumably Villiers Services can also offer similar services too?

Anyway, hope all this is of some use.

Brian.