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Twin carb option ???

Posted: Thu Feb 01, 2024 2:33 pm
by DerekAJS30
When lookiong through the AMAL Carb settings list, for 1957 Model 30 I see carb type 376/78. However there is also a line that shows carbs for the 600 twin "(In Pairs)" with 376/95 or 376/96. I havn't seen paired carbs on a mdel 30, is that really an option. If so, what inlet manifold is used?

Re: Twin carb option ???

Posted: Thu Feb 01, 2024 3:56 pm
by Groily
twin carb heads G9.jpg
I've run twin (concentric 626) carbs on a G9 engine in the past, using what I think were one-off or modded separate splayed manifolds (see pic). Never discovered if there was a 'proper' manifold, nor whether (if there was) it was Norton-ish parallel bores or wide-angle. But the /95 and /96 carbs don't show as 'chopped' like Monoblocs on Notruns (or some big Oilfields too), so I assume splayed.
I had trouble keeping the fasteners up tight on the bits I had, and reverted to a single carb after a bit, with no obvious difference in performance for normal purposes. But they were a talking point!

Re: Twin carb option ???

Posted: Thu Feb 01, 2024 6:45 pm
by ajsph
here is a picture of what I believe is the original manifold.
regards
Poul Hansen Denmark
4_1.jpg

Re: Twin carb option ???

Posted: Thu Feb 01, 2024 7:18 pm
by Joker_Bones
AJS-Matchless-Twin-Carburettor-Manifolds-1.jpg
A picture from the Britcycle website

Re: Twin carb option ???

Posted: Fri Feb 02, 2024 6:48 am
by ajsph
the picture with the 2 manifolds is for a 650cc not a 600cc
Poul

Re: Twin carb option ???

Posted: Fri Feb 02, 2024 8:59 am
by Groily
Interesting thread this (to me), however rarefied the issue might be.
Both the original (never seen that part before Poul, thanks!) and the 650 ones seem to imply a parallel fitment, which depending on space might require a bottom-fed chopped right hand carb? Maybe /95 and /96 376s are . . .? The ones here are off my 650SS (different serial numbers) but the only Monobloc option on those heads as 'handed' ones clash in the middle.
I can't recall seeing any AMC twin with 2 carbs, other than my lashed-up 500, where they sat atop absurdly over-bored (to 70mm) G9 cylinders running equally absurdly high compression (all long-abandoned) - but I probably haven't looked closely enough.

Re: Twin carb option ???

Posted: Fri Feb 02, 2024 4:26 pm
by Joker_Bones
I machined up some two part manifolds and fitted twin concentrics to my G12.
Close fit, but they went on parallel.
That was in 2018, out of curiosity I just looked up the receipt for the carbs... £230 inc. vat the pair from Burlen.
20180728_100233.jpg
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20180728_104956.jpg

Re: Twin carb option ???

Posted: Fri Feb 02, 2024 7:51 pm
by Groily
Bautiful JB, as always! Concentrics, no problem, and boy they look handsome@

Re: Twin carb option ???

Posted: Sat Feb 03, 2024 8:26 am
by ajsph
My G11CS is fitted with twin carburettors, first I used the orignal manifolds, but it was difficult to get them air tight, so I mad my own manifolds version 2
20240203_085956_1.jpg
20240203_085941_1.jpg
, but it was not easy to fit carbuterttors, so next winter I made version 3, they looks like the originals, but I made some internal modifications, and now they are doing the the job wery well.
20240203_085831_1.jpg
Poul

Re: Twin carb option ???

Posted: Sat Feb 03, 2024 8:30 am
by ajsph
I have a 650 with a special manifold,
20240203_090220_1.jpg
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Poul