35 replies to this topic

[DeadSquare]

I have just dug out a Zinc alloy  A30 inlet.

 

The stud centers are 2.09"  (5.31mm)

 

The downdraft bore is .992"   (2.52mm)

 

 

P.S.  If the .992" was bored out to 1.25", there would only be .018", or roughly 1/64" wall thickness. 

[ads7]

Ok I'm going to try sidedraught - will have to make up a hs2 adaptor plate like the one pictured

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Edited by ads7, 26 June 2019 - 07:33 AM.

[ads7]

So this arrived today. Stamped sb6 which is a minnow fish model number. These carbs can be prone to icing and looks like this has had a heater tube fitted in the air filter inlet.

Hasn't been used in thirty years and butterfly is jammed closed so will soak in petrol for a few days to ease off. Once it's freed off and checked over I'll make up an adapter plate then trial fit and hopefully run.

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[cal844]

Jeez the size of that compared to an su!

[ads7]

Side-by-side comparison

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[DeadSquare]

Clive Trickey tried to convince readers of C&CC that a Fish was I the ultimate carburetor, but he didn't have the fastest Mini 7 on the Silverstone straight.

 

On another point, I was told that you can blow through a Fish without any further modification, but I never got around to trying it.

[ads7]

Interesting point on Clive Trickey .. there can be a lot of product hype, just something I'd like to explore.

Yes ideal for forced induction.

[ads7]

Change of plan. appears that it can only be run as a downdraft but I'm not forking out for a maniflow so have to wait until I get proper minnow manifold or make one myself .. this is going to take a while

[ads7]

So back into this project, dismantled notably few moving parts - long hollow arm moves in an arc along an increasingly deep groove allowing more fuel to feed through the arm straight into the butterfly spindle which has three holes which spray atomised petrol.

Fine in theory, however the spindle is partially seized. Plusgas hasn't done the trick so far so time and persistence is called for.

If I can unseize the spindle next job is to find a downdraft manifold. Thinking an SPI one may be workable with an adaptor plate. SPI Mani doesn't look like it would flow very well though?

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[nicklouse]

throw it all in some coke.

it will dissolve the Aluminum oxide.

[ads7]

throw it all in some coke.
it will dissolve the Aluminum oxide.

Thanks getting that done overnight

[ads7]

How long should I leave it to soak?

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[nicklouse]

depends on how corroded. mine was overnight.

[ads7]

Ok thanks I'll give it a few days.

On another subject, does anyone know the inlet hole diameter on the SPI manifold?

I'd be going from 1 1/4" carb using an home made alloy adaptor plate.

[ads7]

Decided to try an A40 Manifold just for trial purposes, still trying to unstick carb after unsuccessful coke soaking