John:
You do not loosen the interconnection for rebalancing the fast
idle (1200-1500 RPM, choke on). Instead, you rebalance using only the
*fast* idle screws. You insert a drill bit (3/16"?? Don't remember the
correct size) between the fast idle cam and the carb body. You must do
this on BOTH carbs when adjusting the fast idle. This sets the cams to a
known reference position. Once this is done, you rebalance the carbs
using the fast idle screws. I then adjust the slack in the choke cables
on both carbs so the tension is equal. I do this by loosening the cable
clips and moving the cable sheaths until the cables match. This is to
insure that when I put the choke on, both carbs are getting the same
"request" from the cockpit.
As for balancing the hot idle (choke off) you only do it once.
Loosen the carb linkage, and adjust each carb (I use the rubber hose -
listen for the hiss method). When the carbs are balanced AND the idle
speed is correct, I tighten the linkage and call it good. When the choke
is on the *fast idle cam* is controlling the idle speed, not the idle
screw - hence no need for the linkage to be loosened for the fast idle
balance adjustment.
If you are really tuning things up, you will also set the
mixture and adjust the bypass valves, as well as the idle CO percentage.
All of this will probably mean you need to go back and reset the idle
speed and rebalance the carbs again.
Personally I do not use the lift the slide test to set the
mixture. I have decided that the mild road cam I have (270 degrees)
lowers the vacuum enough that the lift the slide test does not work (the
engine always stumbles, even if the mixture is so rich that I have black
smoke when idling). Instead I use plug cuts which requires a brief drive
in between adjustments. I must say however, that seeing the spark plugs
turn a nice gray-tan color gives me goose bumps. =:-o
Vance
-----Original Message-----
From: owner-6pack@Autox.Team.Net [mailto:owner-6pack@Autox.Team.Net] On
Behalf Of John Mitchell
Sent: July 17, 2007 7:28 PM
To: 6 Pack; triumphs@autox.team.net
Subject: [6pack] Balancing the Carbs
When balancing the carburettors, Bentley says to loosen the
interconnection, and balance at 850 RPM and re tighten. Then it says to
bring the engine to 1500rpm and re balance with the idle adjusting
screws. Do I loosen the interconnection again when I do this? It then
says to balance with the choke on. Once again, do I loosen the
connector? Seems like you'd just be messing up the balance from 850 and
1500 rpm. Thanks for any help, John Mitchell 76 TR6
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