A little bit of interesting correspondence about Amal carburettors, between Peter Westcott in Australia and Speedwell guru Alistair Ross (read the last letter first and work upwards)
“Hello, Martin. Together I think Alistair and I have nutted out the specs of the Speedwell Amals:
- Amal Monobloc
- The carburettor bodies are marked 376/236 (model/spec). There was also a 376/237 that was the RH float bowl version
- Air Intake tubes 2.3/4″ long
- Speedwell manifolds 1.1/16″ bore x 3.3/4″ length
- Carb Bore 1.1/16″
- Pilot jet 15
- Slide cutaway 2
- Main jet 320
- Needle C
- Needle jet 0.110 (Amal 106)
- Jet Position 3rd (of four) from top
Not a lot of people know that… Peter”.
“Hello, Alistair, thanks for the reply, some interesting details. It’s interesting that they’re only 1-1/16 when there was a 1-3/16 available. Perhaps GH was after high air speed for better torque? The Speedwell’s long manifold runners would certainly have helped in that respect. Either way, the Amals seem tiny, despite having no throttle spindle. I think you’re right about patchy useability and the need for spot-on setup, and I suspect the extended float chambers were to try and cure fuel starvation while cornering, cars behaving very differently to bikes of course. I have no desire to go the Amal route, a simple life is good, but it’s interesting to know what was being tried. My Sprite preference now is for a single HS6/HIF44 SU on a Triton or Russell manifold. I’ve attached a photo of perhaps the ultimate Amal setup on a car, six of them on a ‘50s Holden motor fitted with a Waggot twin-cam head (only nine ever made), and hybridised with SU float chambers. Impressive setup but it would be a bit ’needy’ I think? Also a photo of another response from a 998 Sprite, triple Amals fitted to a common rail with the manifold runners looping over the engine to put the carbs on the dissy side. It apparently worked very well in a very, very narrow rev band. Thanks again for the reply, I look forward to seeing progress on your car. Peter Westcott”
“Hi Peter, The carbs are Monobloc’s (so float chamber is integral with the body) these were originally fitted to a Speedwell clubman head on a 998CC engine. The throat size is 1 1/16″ (27mm) diameter. This set up was a favorite of George Hulbert, but everyone I have managed to speak with says that this set up was difficult to keep in tune, The first owner of my car could never get the car started but as he lived on a hill he could ‘bump’ the car to get it going (patience of an enthusiast) but car would run all day once warmed up. Possibly for the purpose of racing these would work well, but you needed to know your onions in mounting, timing the engine and tuning them. Don Moore (he had long stopped building engines but lived close to me) and I chatted about these Amal carbs and he was a fan,( I think he had mounted 4 onto a pre-war MG?) as at the time I was toying with the idea of rebuilding the 998cc Speedwell engine.(nothing was a problem to him). The carbs do have float bowl extensions and these were made by Amal, the mounting bolt centers are at 2″ (50.8mm). Hope these ramblings help. ttfn….Alistair (Ross)”
I duly forwarded Peter’s message to Alistair whose reply is above:
“I note from the newsletter 2020, that Alistair Ross’ Speedwell GT – 5447 HX (455 EVE) – has a set of Amals with it. I’f you could kindly pass this on I’d be interested to know if Alistair can confirm that they’re Monoblocs, what the throat size is and the spacing distance of the bolts on the mounting flange? I note that the largest Monobloc offered by Burlen is 1-3/16”, which seems a trifle small for a highly tuned A Series engine” – Peter Westcott.
