[Healeys] slow idle setting

[Earl Kagna]

Rich - how timely!  Just got in from the garage touching up the BJ8's carb 
settings after break-in of the engine re-build (to go along with the ground 
up restoration).  Nice to have it on the road again.

Got to disagree with Bob here HD-8's are designed to idle with the throttle 
plates completely closed.  In fact, if they are just slightly open, or if 
there are any air leaks at discs or shafts, they can be very hard to get 
right - the sign is that they don't respond properly to changes in the idle 
air-bleed screws.  One thing that a lot of people miss - the fast idle 
screws might be set wrong - they might be holding the throttle plate(s) open 
slightly, which makes it hard to get the idle screws to respond.  Your home 
altitude might be making it more difficult to get a 'sweet spot' setting.

I would check to make sure that your fast idle screws are clear of their 
cams when the engine is warm and the choke knob is all the way in and try 
again.  My idle screws are approx. 1 3/4 to 1 1/2 turns out at sea level - 
idle speed is approx. 750 / 800 RPM and smooth - surprising for a BJ8, I 
know.  Even at your altitude, yours should not be that different if all else 
is right, even with a bit more advance than spec.  On a BJ8, if the engine 
doesn't diesel after shut off, your idle speed is okay, and you probably 
don't have air leaks.  Timing can affect this too.

Ain't it fun?

Earl Kagna
Victoria, B.C.
BJ8, BT7 tri-carb

-----Original Message----- 
From: Richard Kahn
Sent: Wednesday, April 09, 2014 2:56 PM
To: healeys at autox.team.net
Subject: [Healeys] slow idle setting

I was trying to adjust and balance my HD8s and I cannot figure out the slow
idle.   I am at 6500 ft elevation and the idle is at 800 RPM. When I drive 
at
lower altitudes the slow idle goes to 1000 to 1200 RPM.  Not a problem as 
the
BJ8 runs very well. Yesterday, I tried the "cook book" tuning method. When I
close the slow idle screws then open them 2 1/2 turns the idle is high and I
get black smoke. I turned the screws evenly a half turn at a time until the
RPM went down as low as it would go but the best I could get is 800 RPM. The
screws are now only 1/2 turn open. Again it runs fine. What is going on? I 
am
running the timing a little advanced on purpose. Carbs are balanced and I 
use
two Colortunes to set the fuel mixture. I will be doing a lot of lower
altitude driving this year and was hoping to get this worked out if I can.