another potential cure for run on is the proverbial "Italian tuneup" -- ie
taking the engine out for a good run at high rpm, producing enough heat to
burn off carbon deposits in the head that are presumably what is igniting
the fuel/air mix after the ignition is turned off.
I've had the dieseling problem with my big Healey (SU carbs), and took it
out on a pretty long run yesterday with a fair amount of revving, going up
hills, etc. And, no more dieseling, at least for now! The car had been
running rich for about three years and I finally got the carbs adjusted
properly, I think. (It's interesting that the Healey, with an electric fuel
pump, still managed to diesel even though fuel delivery obviously stopped as
soon as the ignition was turned off.)
haven't had the dieseling problem yet with my "new" 1972 TR6. Didn't seem to
have it at all with my old 1969 TR6, which was in pretty good mechanical
condition and had rebuilt Zeniths. Neither of these cars has the anti-run on
valve.
--Graham
-----Original Message-----
From: tr6taylor@webtv.net [mailto:tr6taylor@webtv.net]
Sent: Tuesday, May 28, 2002 2:39 PM
To: p.h.z@12move.nl
Cc: 6pack@autox.team.net
Subject: Re: Motor keeps running
Zindel---The best insurance for not "running-on" is the proper working
of the anti-run-on valve. (Triumph must have thought this to be good
insurance, or they wouldn't have spent the money) It is also very
possible for engines to not run on without this valve in operation. It
seems to require that the carbs to be properly adjusted. Some books on
the subject of run-on suggest that it's a carb set "too lean" that
provokes the run on, tho it would appear contradictory.
Too high an 'idle' speed encourages run on, by producing more vacuum.
Again, a working anti-run-on valve stops the engine, no matter the idle
speed. (It can't run when there is a depression over the float bowls)
There is a '69 TR in my neighborhood that is a real pistol, when you
turn off the ignition key. A lot of the time, the owner has to put it in
gear and let out the clutch to kill the engine. Low idle speed, 92
octane and proper air/fuel mix only reduces the frequency of this
irritiation. There is no anti-run-on valve in the system, altho I've
been thinking of installing one in his manifold, as described in R.
William's TR6/250 Restoration Book.
Some engines can also continue to run when there is a current leak-back
thru the alternater wiring circuit, altho no dieseling usually takes
place. If you believe this started after you did the Pertonix and carb
work, these seem to be the logical places to retrace your steps.
Dick Taylor
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