If you've adjusted the throttle stop screws and have a good idle going, but
using the Uni-Syn causes the engine to stall, then the idle may be too rich. You
need to adjust the mixture adjusting nut (at the bottom of the carb) by
tightening it upwards in order to lean out the carb. You'll have to adjust the
throttle stop screw to compensate so you'll get a good idle going.
All the information you need to know is in Andy Jacob's message. He said get the
mixture right, then worry about the balance. I doubt that there is any problem
with your Uni-Syn.
Fred - So.SF
__________________________ Reply Separator ___________________________
Subject: Re: finally she started
Author: Matthew W Peterson <pete-3@juno.com>
Date: 5/13/99 5:05 PM
I think I know my problem now. My Uni-syn doesn't create enough suction
to get the bubble to float. I tighten the adjuster on the Uni-syn all
the way down and the bubble still won't float. At this point the car is
on the verge of a stall and the bubble still isn't moving. The only way
I could get it to move was to bring the rev's up to around 2500 so the
other carb could pull enough fuel in to keep it from stalling. At this
point enough suction is created to bring the bubble up. This can't be
normal? Is my new Uni-syn bad or could I be leaking air in through a
manifold or something? There does seem to be a good amount of air being
sucked into the carbs though. My Uni-syn is made by Edelbrock, model "A"
unisyn multiple carburator synchronizer, 4025. Could I have gotten a
wrong model?
Thanks,
Matt Peterson, going to be an expert on SU carbs before I'm done :)
'68 1600
Zimmerman, MN
On Thu, 13 May 1999 15:38:51 -0400 "Andrew Jacobs"
<Legal-Z@worldnet.att.net> writes:
>matt,
>there should be an adjustment on your uni-syn that changes the size of
>the
>opening inside the black rubber ring. this allows the bubble to float
>at
>idle. i.e. the smaller (or is it bigger--i can't remember) the
>opening,
>the greater the amount of air that can flow through the tube, and
>hence the
>bubble floats. just adjust the opening back and forth until the
>bubble
>floats at the idle your car is set at now. as for the rest of the
>adjustment proceedure, you need to know what you're turning first.
>the big
>screws on the bottom that you turned to get your car to start are the
>mixture adjustments. counter clockwise when looking down is leaner,
>clockwise is richer. where they are now is probably a good point to
>start
>at. you need to check your plugs and see what color they are. if
>black go
>leaner and if white go richer. keep doing this (with a short drive at
>operating temperature in between) until the plugs are dry and brown.
>you
>need to check the #1 and #4 plug each time to make sure each carb is
>at the
>right mixture. once you get the mixture right, then worry about the
>balance
>and idle. you use the idle adjustment screws to balance the carbs.
>get the
>idle close to where you want it and then get out the uni-syn (and
>adjust it
>as above). then place it over each carb and see how close the bubble
>is to
>being in the same position on the uni-syn. don't freak because it can
>be
>WAY off. if the height of the bubbles is different, then you have to
>adjust
>each carb--turn the screw on the carb with the higher bubble so the
>idle on
>it is lower (counter-clockwise i think), and the screw on the carb
>with the
>bubble in the lower position clockwise to raise the setting on it.
>remember
>each time you make an adjustment to rev the motor a couple of times by
>hand
>so the engine runs at its true new setting. repeat these adjustments
>until
>the bubble is at the same height for each carb, then see where you
>want your
>idle. adjust up or down accordingly with equal turns on each carb and
>then
>check the bubbles to make sure they are still at the same height, and
>remember to rev the engine after each adjustment. once you've found
>the
>right idle speed, go for a drive and see what happens. when you
>return,
>check one more time with the uni-syn to make sure everything is still
>in
>sync.
>hope this helps,
>andy
<snip>
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