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Re: Blown 948 Dyno Testing results

To: morris@autox.team.net
Subject: Re: Blown 948 Dyno Testing results
From: Robert Greenfield <monster@caverock.net.nz>
Date: Tue, 02 Mar 2004 19:50:55 +0100
I have observed Kevin Wayne Williams <kww@gte.net>'s posting which said:

> At 09:33 PM 2/22/2004 +0100, Robert Greenfield wrote:
> 
> >A heavier dashpot spring would enrichen the mixture, but probably at all
> >rpm, although I can imagine that it would enrichen more at lower rpm.
> >I hope that the data exists somewhere - I've seen adverts from the 1950s
> >for Shorrocks superchargers with Morris Minors in the picture!
> 
> "Heavier dashpot spring" was the wisdom of the world, so I gave it a shot. 
> The dyno will have to wait until next week, but the preliminary tests with 
> a green dashpot spring were very good. Low end performance is back. The 
> yellow spring (8 oz) wasn't much help. Top end may be just a notch off, but 
> some good needle selection at the dyno will probably take care of that. The 
> only noted problem was that if I stomp on it when I am already climbing a 
> hill at 70MPH, it runs rich enough to put a cloud of grey out the pipe. 
> Very few Minor pickup owners can even dream of running the test.

Sounds quite successful already.

> All told, this makes sense to me. A 1 3/4 carb is a lot of carb for a 948, 
> even with a supercharger.

Indeed!
My 2.6L Morris Isis originally had only a single 1 1/2 inch SU...

> The green spring fights the piston rise at the
> bottom, and gives me some air velocity back. Even if the green spring keeps 
> the piston from rising clear to the top, a 948 is never going to demand all 
> the air that this carb can flow.

You've put a lot of thought into this, I can tell!
Even a 1098 has a 1 1/2 inch as standard (if I recall correctly)

-- 
Robert Greenfield
'54 Cowley
'56 Oxford
'58 Isis

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