<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.>
Su are really simple to a adjust and you don't need anything other than a 2
foot piece of vacuum line. IT can be done with out even removing the A/C.
my typing sucks , but any who would like to know how easy it really is, just
call me .
Mike Kerr
Roadster Restoration
3730 Todrob LN.
Placerville CA. 95667
Ph.# 530-644-6777
Fax# 530-644-7252
E-mail: mikekerr@innercite.com
Web page : http://www.innercite.com/~wolfgang
Visa & master card
-----Original Message-----
From: bill/liz wessel <bwessel@itis.com>
To: datsun-roadsters@autox.team.net <datsun-roadsters@autox.team.net>
Date: Saturday, July 31, 1999 8:14 PM
Subject: Re: balancing hitachi su's
>>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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