On 17 May 2004 at 7:33, Jeff Fenwick wrote:
> Are your needles correct? With SU's you set the mix at idle and the
> rest takes care of itself (or doesn't ;-)
Hmmph. (By now I've forgotten the exact details of the original
query, but I'll throw out a few points an yway.) If the car had been
running fine before, I can't think of any reason the needles would
spontaneously become the wrong ones! :-) If it was a new install of
carbs from a very different source, then "the rest" doesn't
necessarily take care of itself. Specifically, if the springs aren't
correct for that engine size, the needles will never be correct. For
example, on my GT6 a DPO had installed H4S SU's from an MBG. The
softer springs were meant for the smaller displacement. The result
was that at part throttle the springs opened too much and the mixture
ran lean. When the throttle was opened enough the pistons would
bottom out (actually, top out) and the mixture would get richer. At
full throttle it would run like a banshee but it could not be made to
run well at part throttle and idle simultaneously.
Just my $.007.
--
Jim Muller
jimmuller@pop.rcn.com
'80 Spitfire, '70 GT6+
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