>hi,
> i was just about to go out to adjust my carb's(first time) when i
>discovered that i deleted some great instructions sent to me by mark from
>baltimore . no can do without 'em. he sent a link w/ great info...cant
>remember the address. can anyone help ?
>thanks,
>dennis
>1969 1600
Dennis et al,
WARNING...DANGER...Will Robinson! Do not approach "balancing the carbs"
without some somber soul searching ...and the correct tool! YOU MUST HAVE A
UNISYN! And know how to use it.
Alot has been written about carbs and I don't have to repeat it. Do a
search on SU's, SU carb or "Skinners Union" and you'll find a wealth of
pages. The "shop manual" has good info as does the Chilton manual. I think
it's Roger Garnett who wrote an excellent description...it's at least a two
or three pint job!
Do ensure that you've checked the dwell, valve lash, compression, fuel
float level, cleaned the screens and have a good filter, 3-4 psi pressure,
timing (smogged and/or non-smogged distr?), good engine ground, do your
throttles open all the way with the pedal on the floor (engine off)? make
sure all of that stuff is good before you touch the mixture and idle
screws. And then make sure you understand what you're attempting to do.
I know your probably thinking I'm blowing alot of smoke, but hear me
out....it is extremely easy to totally mess up such that your car won't
even start. I have EGT gauges on the race car and I still take out a
rachet, turn it upside down, to tell myself in which direction to turn the
mixture.....and that's just mixture. Without EGT gauges (really only
necessary (and readable) on a race car at sustained full throttle), you're
relying on the lifting pins and plug color.
The unisyn measures the flow of air thru the carb. This tells you that the
butterflys are approximately equal. This is a separate issue from mixture
(are you still with me?). Adjustment is made at the set screws on the
throttle shafts, with the "links" off, at idle. You must size your "links"
equal (I use a caliper) to each other, then connect them up and recheck at
3000-4000 rpm (this is where the engine lives) (screw down the throttle
stop by the cable to set the engine speed, not the carb idle you just
adjusted)(close down the unisyn) to check that the butterflys are still in
sync. Use the link length to make further adjustment. You especially want
the carbs balanced at 3000-4000 rpm. BTW, your neighbors are really going
to wonder what the hell you're doing with your car at those revs...just
sitting there, tinkering in the drive! But if you've done it right and
there are no air leaks in your suction pistons, your piston springs are
matched, and your mixture is approximately correct, and fuel level
also...the balance will be the same at 3-4k rpm.
One more thing-too often I've seen a manifold vacuum line routed to the
vacuum advance or the "breather"/air cleaner. On a 1600, the vacuum advance
line to the distributor should be connected to the port off the bottom of
the rear carb throat. On the 2000, that port is on the top of the front
carb throat. Any line off the intake manifold should be plugged if it's not
going to a properly connected and functional smog equipment and/or
thermostatic valve.
SU carbs are really a marvel of simplicity, when you understand how they
work, and contrary to popular belief, they do not "go off". The dwell,
valve lash and timing "go off" much easier...I have not touched the carbs
on my street 1600 for at least 6 years and I've only adjusted (tweaked) the
mixture on the race car to compensate for temperature and humidity.
PS. Tom is quite right about the torque on the rocker cover. Like I said, I
use a hand wrench and just snug it up. I quess the torque (and it was a
quess) is more like 10-20 ft-lbs. My Popeye forearms....argh, argh, argh!
Bill Wessel
Madison, WI
'68 1600, '69 2000,
and GP race roadsters
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