One thing I forgot to put in my writeup concerns the jet. Be sure that it
slides up and down smoothly and doesn't hang up anywhere. Cycle the choke
linkage from off to full and back again and watch for hangups. Once the
choke is off make sure that the jet is fully seated against the centering
nut.
Actually, our carbs don't have "chokes", which choke off the airflow.
Pulling the manual choke on the dash lowers the jet, allowing more fuel
into the mixture. So, instead of a choke, we have an enrichening system.
Same end results, just different method!
Peace,
Pat
- Support Habitat for Humanity, A "hand up", not a "hand out" -
Pat Horne, Network Manager, Shop Supervisor, Future planner
CS Dept, University of Texas, Austin, Tx. 78712 USA
voice (512)471-9730, fax (512)471-8885, horne@cs.utexas.edu
On Sun, 31 Mar 2002, Patrick J. Horne wrote:
> Oops, I need to proof what I say more! Yes, it is the CHOKE linkage.
>
> Peace,
> Pat
>
> - Support Habitat for Humanity, A "hand up", not a "hand out" -
>
> Pat Horne, Network Manager, Shop Supervisor, Future planner
> CS Dept, University of Texas, Austin, Tx. 78712 USA
> voice (512)471-9730, fax (512)471-8885, horne@cs.utexas.edu
>
> On Sat, 30 Mar 2002, Adam Bradley wrote:
>
> > When you say "cloak linkage", do you mean "choke linkage", or is this
> > something else?
> >
> > --- "Patrick J. Horne" <horne@cs.utexas.edu> wrote:
> > > Before you adjust the carbs it is best to be sure that the rest of
> > > the
> > > engine is in good shape. Make sure the valves are adjusted correctly,
> > > the
> > > ignition (points, plugs and condenser and timing are correctly set
> > > (Points
> > > and condenser are not on your new distributor. Check the plug wires
> > > to be
> > > sure they are good.
> > >
> > > Once you know everything else is correct it is time to adjust the
> > > carbs.
> > >
> > > Remove the air filter and reach into the throats of the carbs and
> > > lift the
> > > pistons up as high as they will go. Let each one fall and listen for
> > > a
> > > "click" when it reaches the bottom. A "thud" or scraping sound, or
> > > the
> > > piston not dropping all the way means that you need to center the
> > > jet.
> > > This is a time consuming bit of trial and error until they are set
> > > correctly. I prefer to raise the jet as far as it will go to do this
> > > adjustment so the fattest part of the needle is as high as possible.
> > > Record the settings of the mixture so you can set them back where
> > > they
> > > were after you are finished. Loosten the nut above the mixture
> > > adjustment
> > > and lift/release the piston to see if it will drop all the way down.
> > > (the
> > > nut doesn't have to be really loose, just loose enough to allow the
> > > jet
> > > holder to move sideways a little. Tighten the nut and check again.
> > > Keep
> > > doing this until the carb "clicks". Reset the mixture and move to the
> > > other carb.
> > >
> > > The reason that you have very different readings with the unisyn is
> > > that
> > > the throttle butterflies in the two carbs are set differently.
> > > Disconnect
> > > the dumbell linkage from both carbs so that the throttle linkage is
> > > disconnected from both carbs. Make sure that the cloak linkage is not
> > > holding one of the carb jets down a bit. Start the car and adjust the
> > > idle
> > > speed adjusts (on the linkage for the butterflies) until the unisyn
> > > shows
> > > the same reading on both carbs. You may have to change the settings
> > > on
> > > both carbs until they are the same and idling at about 700~800 RPM.
> > > The
> > > readings need to be the same with the unisyn adjusted the same for
> > > each
> > > carb. By adjusting the unisyn you are changing the range of the
> > > unisyn.
> > > That should get the carbs in sync at idle.
> > >
> > > Next connect the throttle linkage on one carb. The unisyn should
> > > still
> > > show equal readings. Now adjust the dumbell for the other carb so
> > > that the
> > > length of the dumbell matches the location of the ball on the carb
> > > linkage. Just for fun check the balance again.
> > >
> > > Now it is time to set the idle mixture. There is a lift pin on the
> > > bottom of the carb, just below the throat, I believe on the side
> > > opposite the float bowl. Use this pin to lift the piston for a
> > > second or two. If the engine revs up a little, then slows down to a
> > > bit less than what it was running at idle, it is about right. Try
> > > the same with the other carb and go back and forth until they are
> > > the same. Adjust the nut around the jet on the bottom of each jet to
> > > make
> > > mixture admustments.
> > >
> > > Open up the setting on the unisyn and have someone rev the engine up
> > > to
> > > about 3000RPM. Check the balance again, it will probably be off by a
> > > bit.
> > > Adjust the dumbell until they match. (The idle balance will probably
> > > be
> > > off a bit, but not much.
> > >
> > > Go through the settings again and keep at it until it is running
> > > right.
> > >
> > > After spending the better part of a day going through all of this it
> > > is
> > > time to take a spin to see how your handwork did. Upon return treat
> > > youself to a beverage of you choice and relax!
> > >
> > > Peace,
> > > Pat
> > >
> > > - Support Habitat for Humanity, A "hand up", not a "hand out" -
> > >
> > > Pat Horne, Network Manager, Shop Supervisor, Future planner
> > > CS Dept, University of Texas, Austin, Tx. 78712 USA
> > > voice (512)471-9730, fax (512)471-8885, horne@cs.utexas.edu
> > >
> > > On Sat, 30 Mar 2002 WisslerJon@aol.com wrote:
> > >
> > > > Gary,
> > > >
> > > > You were absolutely correct. I was adjusting the damn air mixure
> > > screws and
> > > > not the idle screws. I finally figured out what the hell was going
> > > on.
> > > > Fortunately for me, a neighbor who restores old Mercedes stopped by
> > > and told
> > > > me I had to adjust the Unisyn to get a reading (as you said) and
> > > voila !!
> > > > Now the only problem is no matter what I do I can't get both carbs
> > > to get the
> > > > same reading. The rear carb, when covered by the Unisyn, causes
> > > the motor to
> > > > stumble a bit. I have the air mixture screw baily opened on that
> > > one. The
> > > > front carb barely gets a reading practically no matter what the
> > > heck I do. I
> > > > have it opened SEVERAL turns. Does this mean that my carbs are
> > > essentially
> > > > toast do you think? Despite the fact I probably have the SU's
> > > nowhere near
> > > > tuned, I went out for a test spin and WWWWWWWOOOOOOOOOWWWWWW !!!!!
> > > The car
> > > > absolutely hums !! No more stall at low RPM's, and if I punch the
> > > throttle
> > > > there is INSTANT response. Major improvement. Thanks again for
> > > such a fine
> > > > product, the excellent instructions, and the follow up advice. The
> > > wife and
> > > > I will heading out to dinner in the sunset tonight and I may be
> > > scaring the
> > > > hell out of here with my driving.
> > > >
> > > > 69 2000 (With the most excellent Gary Boone EI dizzy)
> > > > 69 510 Wagon L20B (With the dash removed waiting for a dash clock)
> > > > 69 Chev C10 4x4 307 2bl (HEI, Edlebrock manifold and carb waiting
> > > in the
> > > > garage)
> > > >
> > > > (I think I have too many things going at once !!!)
> > > > NOWROC
> > > > Troutdale, OR
> > > >
> > > > /// datsun-roadsters@autox.team.net mailing list
> > > > /// Send admin requests to majordomo@autox.team.net or go to
> > > > /// http://www.team.net/cgi-bin/majorcool
> > > > /// Send list postings to datsun-roadsters@autox.team.net
> > >
> > > /// datsun-roadsters@autox.team.net mailing list
> > > /// Send admin requests to majordomo@autox.team.net or go to
> > > /// http://www.team.net/cgi-bin/majorcool
> > > /// Send list postings to datsun-roadsters@autox.team.net
> > >
> >
> >
> > =====
> > Thanks,
> >
> > Adam Bradley
> > '70 Datsun 1600 Roadster SPL311-28181
> > '66 Datsun PL411 sedan PL411-022447
> > http://www.picturetrail.com/abend
> > Yahoo! Greetings - send holiday greetings for Easter, Passover
> > http://greetings.yahoo.com/
>
> /// datsun-roadsters@autox.team.net mailing list
> /// Send admin requests to majordomo@autox.team.net or go to
> /// http://www.team.net/cgi-bin/majorcool
> /// Send list postings to datsun-roadsters@autox.team.net
/// datsun-roadsters@autox.team.net mailing list
|