All,
Thanks for all of your input. Some fresh 30wt oil in the dashpots helped a
lot. It still stumbles but not nearly as much. One of my books suggested
that if you raise the dashpot piston manually 1/32" and the engine speed
falls, that the mixture is too lean. Given that, both carbs are too lean.
So the next step is to adjust them until they pass this test. But the plugs
are tan/brown after a drive... sooty if it idles for a while.
Perhaps it is time to get an S.U. kit and a Unisyn. Or a Gunson
Carbalancer. Their Clickadjust looks interesting too. Anyone tried these
out?
Thanks!
Tim Benner
1965 MK2
-----Original Message-----
From: sinclair@degenkolb.com [mailto:sinclair@degenkolb.com]
Sent: Monday, July 28, 2003 1:04 PM
To: spitfires@autox.team.net
Cc: Tim Benner
Subject: Re: 1147cc tune-up carb problems
Check your vacuum advance - the diaphragm may be shot in which case you're
not getting enough advance when you jump on the pedal.
Also - you can try power-timing - keep advancing the timing, test drive,
listen for knocking, and then back off slightly from there. You can often
run more advance than the manual indicates.
If the vacuum advance is shot then advancing the timing will compensate for
to some degree - i.e. better acceleration, but it will knock at high
revs/load.
-----------------------------------------
Date: Sun, 27 Jul 2003 09:43:23 -0400
From: "Tim Benner" <tbenner@woh.rr.com>
Subject: Re: 1147cc tune-up carb problems
Thanks for all of your responses.
It revs well from idle (no load). But this is just blipping the
throttle...
don't want to alienate the neighbors.
Today I will:
Change the dashpot oil (30 wt OK?)
Recheck the timing.
Drive it again and choke it when it stumbles.
Order some float valves.
After reading the Haynes and Clymer manuals last night the SU doesn't seem
as intimidating. So I'll get out the spare pair and start cleaning them
up.
Any other recommendations?
Thanks again!
Tim Benner
1965 MK2
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