William-
Make sure each air valve is free within
it's housing by raising the airvalve fully
and letting it drop. The air valves should
drop freely at the same rate and contact
the jet bridge fairly gently with a dull
"thunk". Assuming they do, proceed.
(If not, get back to us before you proceed!).
Set jets with MIXTURE hex nuts (bottom
of carb.) flush with jet bridge as before.
(Nuts are usually pretty much fully clockwise as far as they will go at
this
point).
Back off throttle IDLE screws with
"interconnect" loosened clear of their
carb. "platforms". Screw these back in
until they just touch their respective
"platform", then keep going "in" 1&1/2
turns. This is the IDLE basic setting.
Make sure the choke adjusting screw
is "clear" of it's cam on the carb. with
the choke control fully in. Don't want
any choke action while you're doing
this, obviously! :)
Now, turn each MIXTURE hex nut out
(counter-clockwise) 12 "flats" (= two
full turns of the nut). This is the MIXTURE
basic setting.
Start the engine. Using a portable tach.
set the idle at about 800rpm by the
IDLE screws. Do this
while using a Unisyn or other "airflow"
measuring device. You are setting idle
and balance simultaneously at this point.
By this time the engine is obviously
at correct operating temp.
Test mixture strength on each carb. by
lifting the air valve 1/32nd". You can
use the carb. lifting pin for this or
squat down and use a small "flat" screwdriver for this.
If mixture "correct" (not likely!):
As the air valve is lifted that scant
amount, the idle speed should momentarily increase and then return
to the previously set idle speed (or very
slightly lower) as you continue to
hold the air valve open. You can see
where the "sensitivity" of a portable tach.
is very useful here so you can "see"
slight idle speed changes which may
be masked to the ear by engine noise.
If the idle speed increases and remains
increased as you hold the air valve off
the jet bridge that 1/32nd", the mixture
is too rich. Turn this carb's. mixture adjusment nut "in" (clockwise) 1
flat.
If the idle speed decreases when you
lift the air valve slightly off the jet bridge,
the mixture is too lean. Turn this carb.'s
mixture adjust. nut "out" (ccw) 1 flat.
Do the same with the other carb., then
come back to the first carb. and go
through the procedure again, doing
what is necessary with the carb adjust
nut for "too lean" or "too rich" as you
go. Remember the carbs. are inter-dependent. One's setting affects
the other's as they share a common
intake manifold. Go back and forth
between carbs in this manner while
performing this procedure until you
get that momentary increase in idle
from each one.
That's why you go from one to the other
to adjust the mixture as a whole and do
not adjust one carb. until it is "right"
than go to the other and adjust that one
until it is "right". You adjust one, than
the other until they are both right.
Some guys lift the airvalve on one
carb. and adjust the other for mixture
strength. That's ok too, because in the
end the mixture is adjusted as a "whole"
so either way, the end result is gonna
be the same, anyway.
Once you have the mixture strength
"correct", the idle speed will probably
have changed a bit. Readjust the idle
screws as required by an equal amount
using the Unisyn of whatever "airflow"
detecting device you're using.
Now carefully tighten up the carb.
interconnect linkage and recheck
the "balance" between carbs. afterward.
One carb. shaft can "move" as you
perform the tightening of the interconnect
and it can throw the balance off to that
extent. You may have to do this a few
times, accordingly until you get it right.
Now, open the throttle to 1200-1500
rpm and check balance again. It should
be very close to spot on. If not, balance
for either this position or idle position.
It's usually pretty close so this is usually
not necessary, but if not, I'd balance
for high idle rather than low.
That's about it, big guy! Time for me
to visit the bar area for a KettleOne
Vodka tonic and some good Eric
Clapton ole' style music!! C'ya! :)
Cap'n. Bob (Ret'd)
'60 Frog
/// unsubscribe/change address requests to majordomo@autox.team.net or try
/// http://www.team.net/mailman/listinfo
/// Archives at http://www.team.net/archive/spridgets
|