76 AV/IED Pre Monobloc Replacement for 1954 AJS M16

Information relating to the Matchless G3 or AJS Model 16 350cc Heavyweight
uas526
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76 AV/IED Pre Monobloc Replacement for 1954 AJS M16

Post by uas526 »

I think my old monobloc is finally too worn to be fit for purpose. I changed all the internals a few years ago (slide, jets, etc.) but now I can't get in to provide a steady tick-over. Sometimes it's too fast, then too slow, or conks out and then needs flooding to start again. I drive in heavy traffic, so good tick-over is important. I am seriously thinking of replacing it with a monobloc. The bore of the pre-monobloc is 1". So, my questions are (1): will one of the clubs 376/16 .376 AMAL 1" monoblocs be the correct 'replacement'? and (2) will the set-up provided on the carb suit my 54 Model 16. Thanks for any guidance.
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Re: 76 AV/IED Pre Monobloc Replacement for 1954 AJS M16

Post by Tazmantic »

Hi someone with much more knowledge will be along shortly I’m sure but I thought it should be 1 1/16 bore ? As that’s what I’m going to fit to my 55 but yes I believe a monobloc should be ok.
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Rob Harknett
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Re: 76 AV/IED Pre Monobloc Replacement for 1954 AJS M16

Post by Rob Harknett »

The correct carb for 1954 16M is 76AV/IED ( Used only for 1954 ) The link below will give you all the parts required for your 1954 16M
Jets etc etc etc. If you order a carb you will need this info so you get a carb fitted with all the correct parts for your bike. Mono bloc carb was introduced 1955.
http://archives.jampot.dk/technical/Car ... 54_AMC.pdf
Last edited by Rob Harknett on Sun Jun 20, 2021 10:25 am, edited 1 time in total.
SPRIDDLER
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Re: 76 AV/IED Pre Monobloc Replacement for 1954 AJS M16

Post by SPRIDDLER »

I've had a 376 1" bore Monobloc instead of the originally fitted 76AV pre-Monobloc on my 1954 350 for 19 years (it was £104 from Club spares!) and it has performed fine.
Cruises comfortably for extended motorway and dual carriageway periods with full camping gear at 60mph (GPS verified). No idea of top speed as I've never seriously wrung its neck but have had a tad over 70mph (indicated) in occasional short bursts. Been over the Alps and the Pyrenees a few times.
If your pre-Mono is 1" and you fit a 1 1/16" replacement there'll be a 1/32" mismatch ridge between the bore of the carb and the carb spacer but TBH I don't think it would be an issue.

P.S. I can't find my note of the settings at the mo and I'm going out now for the day but as far as I recall (from 19 years ago) it is still as set by club spares. If vital I'll have a look at the actual carb later but the bike's at the back of the shed behind another............ where it has been for the past 18 months :cry:
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Pharisee
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Re: 76 AV/IED Pre Monobloc Replacement for 1954 AJS M16

Post by Pharisee »

SPRIDDLER wrote: Sun Jun 20, 2021 10:20 am
If your pre-Mono is 1" and you fit a 1 1/16" replacement there'll be a 1/32" mismatch ridge between the bore of the carb and the carb spacer but TBH I don't think it would be an issue.
The fibre spacer could easily be blended to match an extra 1/16" of carburettor bore.
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uas526
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Re: 76 AV/IED Pre Monobloc Replacement for 1954 AJS M16

Post by uas526 »

Rob, Tasmatic and Spriddler. Many thanks for all your useful replies. Great to have that 19-year road test from Spriddler. I will order one of the 1" 376 carbs from the club and try to recommission the 76 AV/1ED at my leisure. The club does the 1" bore to suit the 54; the 1 1/16 came afterwards (55).

Just tried to tune up the pre-monobloc one more time, but to no avail. When I last cleaned and inspected the old carb a few weeks ago, I noticed that the choke slide had been set to always be very partially closed (i.e. a small amount of choke). Probably why it was always running way too rich, no matter what I did. Perhaps this was done to offset the worn carb by the PO. It's now on the original settings. I could reset the choke as before, but then I'm back to a too rich mixture. The other problem with the pre-monoblocs is they tend to be leaky.

The 76 AV/1ED carbs are out of stock everywhere, and are £100 more than the 376. So a monobloc it will be.

Will I need to order new cables as well, or will the old ones fit?

Thanks again, much appreciated.
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Duncan
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Re: 76 AV/IED Pre Monobloc Replacement for 1954 AJS M16

Post by Duncan »

HI Aaron, it may be worth calipering the cylinder head as in 1954 the bore increased to 1 1/16"
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Rob Harknett
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Re: 76 AV/IED Pre Monobloc Replacement for 1954 AJS M16

Post by Rob Harknett »

http://archives.jampot.dk/technical/Car ... 60_AMC.pdf
Compare 55 with posted earlier 54 link
I assume you have checked your old carb has all the correct parts, slides, jets, needle etc
uas526
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Re: 76 AV/IED Pre Monobloc Replacement for 1954 AJS M16

Post by uas526 »

Hi Duncan, that's a good point! I'll whip the carb off in a bit and check, to be sure. Many thanks for that.
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Re: 76 AV/IED Pre Monobloc Replacement for 1954 AJS M16

Post by uas526 »

Hi Rob, I'm pretty sure that all is correct, as I replaced all the usual parts c. 5 years ago, but I'll check all again when I remove the carb. It's the sort of bike that hasn't been messed with...hence all the original, patinated (i.e. slightly rusty parts). Thanks.
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