To the folks who are having trouble with the lift-pin test on SUs...
It is tricky! The manual says something about lifting the piston 3/32"
or something silly like that. If you lift the piston too far, you will
ALWAYS get the symptoms of "running too lean" (surge and die). You want
to lift the piston just far enough for the RPMs to change and hold it
there. It really is a very small amount.
Also, make sure your idle is set low enough. The pins (on the HIF4s
anyway) only go so high. If the idle is set very high the piston is
already elevated and you might lose any adjustment range. Watch the
piston itself as you are lifting to confirm the lift distance.
On the HS2s in the Spitfire, the jet positioning mechanism itself is worn
and the jet won't sit still at a setting leaner than about 8 flats down.
This makes adjustment impossible and misleading in that range.
I use plug cuts because that allows me to adjust for either cruise or
accelleration tractability. No, they aren't supposed to be different
settings if you have the proper needle for your engine/intake/exhaust...
but after playing with those three parameters I don't think my needle is
100% compatible. Make sure you cut the engine during or right after the
driving style you are optimizing for (don't let it idle for a long time
unless you are just checking idle mixture).
The Colortune works quite well on a system which is actually working.
The other methods work better on a system with worn carbs, air leaks
(fix!) or mismatched needles.
For those of you who are interested in stories, check out the Website and
ftp server at autox.team.net. They have digests from 91 forward (I
believe) and cover the "golden age" of Scott Fisher stories, etc. I have
stories I relate every now and then but am overshadowed by the real
writers on the list.
Let's see, there's the "Something's On Fire under the Dash at Night and
the Headlights Go Off" story, the "Something's On Fire Near the Radio
when I'm on a Hot Date and the Headlights Go Off" story, the "300 miles
from Home and It's Raining Buckets Inside the Car" story, the "Ignition
Fails Completely at an Autocross" story, "Engine Ingests Screw and Dies 5
Miles from Home, Requiring Complete Rebuild" story... where shall I
begin? <g>
John M. Trindle | jtrindle@tsquare.com | Tidewater Sports Car Club
'73 MGB DSP | '69 Spitfire E Stock | '88 RX-7 C Stock
Home Page: http://www.widomaker.com/~trindle
"I feel more like I do now, than I ever have before - Arlo Guthrie"
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