Gary, I have reviewed the several different sources available to me on
adjustments of the HD8 carburetor, and I have to agree that they all specify
using the "Slow Run Valves" (only), to control the idle speed, with the fast
idle screws being used to control the fast idle through the choke when the
engine is cold. I'll update and correct my procedures based on that.
Thanks for pointing it out.
My annual tune-up will occur soon, and I'll see how the updated procedures
work for me. The procedures as they are have been working fine for me for
several years and it will be interesting to see how the change makes a
difference.
The re-review of the various sources (workshop manual, SU manual, Chilton's
and Glenn's repair manuals) reminded me again how confusing they all are in
using different nomenclature for the same part, different idle speeds,
referring to other sections that don't apply, etc.
Steve Byers
HBJ8L/36666
BJ8 Registry
Havelock, NC USA
From: warthodson at aol.com [mailto:warthodson at aol.com]
Sent: Saturday, April 07, 2012 8:08 PM
To: sbyers at ec.rr.com; healeys at autox.team.net
Subject: Re: [Healeys] HD8 adjustment
Steve,
I have a copy of your excellent instructions & follow the procedure with one
significant exception. Your instructions state that the slow run valves
(what I called the idle screws) are used to set the Idle at 500 RPM, then
(after the mixture & balance are set) the fast idle screw is used to raise
the idle to 1000 RPM.
The exception is, that it is my understanding that, the idle should be set
entirely with the slow run valve & the fast idle screws are set so that they
are not in contact with what you call the throttle shaft stop lever. The
fast idle screw should only contact the throttle shaft stop lever when the
choke is pulled out. The choke actually performs two functions in sequence,
(1) is to raise the idle speed & (2) is to lower the main jet to richen the
mixture. However, on the HD8's that I have attempted to adjust, I cannot
raise the idle speed high enough with the slow run valves & am forced to
raise the speed with the fast idle screw. So I do end up using your
proceedure, but it conflicts with what I have read & Jim Taylor used to
teach.
One point of clarification. With HD8's, I can get the idle up to 500 RPM
with the slow run valves but not up to 1000 RPM with the slow run valves.
With HD6's I can.
Gary Hodson
|