On 11 Oct 2006 at 22:40, OKCSpitfire wrote:
> I notice that the needle was flat on one side,...
> Two days ago I pulled the top of the carb off and dumped
> some of the damper oil 5w 20 and for the past
> two days it drive like it is suppose to
The flat-spotted needle should make the mixture run rich. The effect
of the dashpot oil is to keep the mixture from becoming too lean
whenever you move the throttle to a more open position. In theory
this happens only during and slightly after movement of the throttle,
not during simple cruising. But in practice you may be moving the
throttle continuously up and down a little so that the dashpot is in
constant motion. By dumping some of (or perhaps all of) that oil you
may have reduced the non-leaning effect, compensating somewhat for
the fact that the needle is letting too much gas in.
At least that's the theory of how it should work.
If it was mine I'd replace the needle (call Joe Curto
joecurtoinc.com) and restore the dashpot oil.
On the other hand, someone might just tell you that on the model 221B
Baker St carbs on '76 Spitfire the needle was supposed to be flat.
--
Jim Muller
jimmuller@rcn.com
'80 Spitfire, '70 GT6+
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