Yes, I thought someone would point this out. You may be right, Perry.
However, the procedures say "Pull the choke knob at the fascia until the
linkage is about to move the carburettor jet operating arm (emphasis is
mine) and adjust the fast idle screws to give an engine speed of about 1000
RPM when the engine is hot."
About to move the jet operating arm, but not quite, i.e. the choke is pulled
out to the limit just short of moving the jet. And why would you adjust the
choke while the engine is hot unless to ensure that it isn't functioning
under those conditions?
As I said, these procedures are not the clearest I have ever seen. I'll
have to go through them again to see if my interpretation has changed based
on your and Earl's input.
Thanks,
Steve
-----Original Message-----
From: healeyguy@aol.com [mailto:healeyguy@aol.com]
Sent: Friday, June 23, 2006 12:20 PM
To: healeys@autox.team.net
Cc: sbyers@ec.rr.com
Subject: Re: Dieseling
Steve
I believe the key is in your statement: "all of the sources describe
adjusting the choke and then
setting the idle with the fast-idle screws to give 1000 RPM with the
engine
hot, which is what I do."
I believe that this procedure indicates setting the fast idle (while choke
is in use) and not the normal (slow) idle. If the fast idle screws are on
the stops with the choke off the throttle plates are open. This adds to the
dieseling problem.
Aloha
Perry
-----Original Message-----
From: BJ8Healeys <sbyers@ec.rr.com>
To: Healey List <healeys@autox.team.net>
Sent: Fri, 23 Jun 2006 11:30:33 -0700
Subject: RE: Dieseling
Hi, Earl -
I agree with you that too high an idle speed can promote dieseling. Also
high compression and low octane gas.
I have several sources for carburettor tuning (Haynes SU Carburettors Owners
Workshop Manual, Glenn's A-H Repair and Tune-up Guide, Chilton's Repair and
Tune-up Guide for the A-H). Given that the procedures in none of them are
completely unambiguous and clear (some of them actually conflict), as I read
them it says to adjust the idle speed with the throttles closed using the
"Slow Running Valve" to achieve 600 RPM (or 500, or 1000, take your pick)
while balancing the airflow in the carbs. I'm assuming this low RPM is to
make sure the mechanical advance of the distributor isn't affecting timing.
To finish up, all of the sources describe adjusting the choke and then
setting the idle with the fast-idle screws to give 1000 RPM with the engine
hot, which is what I do.
Because of the inconsistencies (even the same manual uses different
nomenclature for the same screw, for example) and ambiguities, I
consolidated the three sources into my own procedures for my own use. These
have worked well for me, but I'm always willing to learn something if I am
interpreting the process incorrectly. I know my BJ8 doesn't want to idle
very smoothly at 600 RPM though.
The funny thing is when they tell you to lift the pin 0.031 in. - 0.8 mm.
Yeah, right!
Steve Byers
HBJ8L/36666
BJ8 Registry
Havelock, NC USA
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