Monobloc Carb Install Sequence

Information relating to the Matchless G15 or AJS Model 33 750cc twin. This also includes the G15 Mk II and the G15/45
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Gerard Harrison
Posts: 72
Joined: Sun Nov 21, 2010 6:45 am
Location: Nassau USA

Monobloc Carb Install Sequence

Post by Gerard Harrison »

In the name of all things holy...can anyone state with authority how my Amal 389 monoblocs are supposed to be installed on my G15 Atlas motor?

A general Google search renders up a complete set of conflicting threads on the subject in various Norton/Triumph etc forums.

So starting with the piece parts.....

-We have a Motor Head with studs on either side of the 2 intake ports
-We have 2 Manifolds w/balance tubes
-We have 2 resin/bakelite Heat spacers
-We have ?? paper gaskets
-We have the 2 carbs with rubber O-ring gaskets

Now I have used all my powers of deductive reasoning and reading comprehension to arrive at one indisputable fact as follows:

-The carbs with the O-rings are the LAST thing to be mounted on the head studs....there seems to be general agreement concerning that concept on most of the Web Boards

Could someone please advise me as to the proper sequence of sliding the pieces onto the head studs?

Does the Heat Spacer go on first or do the manifolds?

Which mating joints of which components get Paper Gaskets sandwiched between them?

I would have thought this would be a straight-forward question to ask but in web researching it,, I think I would sooner find the answer to how many angels can dance on the head of a pin....

before I'll read anything definitive on this

Please help or add to the confusion as you see fit

Thanks as always
Gerard



Edited by - Gerard Harrison on 22 Mar 2011 05:14:33 AM
petert120r
Member
Posts: 437
Joined: Fri Jan 03, 2003 12:00 am
Location: POWYS UK

Monobloc Carb Install Sequence

Post by petert120r »

1: manifolds to heads with paper gaskets on joint faces (and smear of Wellseal or similar)
2: heat spacers with paper gaskets between spacer and manifold joint faces
3: carbs with "O" rings to heat spacers, no paper gasket - you don't need them with "O" rings

At the risk of teaching granny how to suck eggs, don't overtighten any of the fasteners, particularly the ones securing the carbs to the manifolds as it's easy to distort the carb flange. Finger tight then half a turn is plenty.Edited by - petert120r on 22 Mar 2011 11:54:40 AM
Gerard Harrison
Posts: 72
Joined: Sun Nov 21, 2010 6:45 am
Location: Nassau USA

Monobloc Carb Install Sequence

Post by Gerard Harrison »

Thank you Peter...the logic is impeccable

and is what I more or less thought would be the case

I ran across debates on the heat spacer's location...some said against the head and others as you suggest

I believed the heat spacer would be more effective after the manifolds took the brunt of the heat from the head

and yes I did get an education on the idea that I only need a good seal on the O-ring and to not mash it flat and kill my flanges...

it never hurts to state the obvious for the benefit of the oblivious
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