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Re: EI Dizzy Conversion/Now Idle Speed and SU tuning

To: Adam Bradley <ambradley@yahoo.com>
Subject: Re: EI Dizzy Conversion/Now Idle Speed and SU tuning
From: "Patrick J. Horne" <horne@cs.utexas.edu>
Date: Sun, 31 Mar 2002 07:50:24 -0600 (CST)
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
> > >
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>
>
> =====
> Thanks,
>
> Adam Bradley
> '70 Datsun 1600 Roadster SPL311-28181
> '66 Datsun PL411 sedan PL411-022447
> http://www.picturetrail.com/abend
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