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Re: carb. adjustment

To: Mike <datsun_sports@hotmail.com>
Subject: Re: carb. adjustment
From: "David R. Conrad" <conrad1@gte.net>
Date: Fri, 30 Aug 2002 10:29:56 -1000
Mike:

Please see comments.  I'm certainly no expert, but I do have mine working great
(finally).  It doesn't "sound" like you adjusted them with Colortune, but with
a Unisyn.

Mike wrote:

> hi,
>
> I have adjusted the carbs with the colortune and they are sucking at the
> same rate. my early 67 with dual SU's idles at 1500 right now. it is doing
> so smoothly also. however I am confused on the procedure for adjusting the
> to idle at around 600 per my service manual.

I use 800.

> the air rate was adjusted using
> the small slotted screw mounted on top of each carb that sits behind the
> damper housing.

That is correct. but it must be done with the "dog bone" links to the throttle
actuating shaft, removed.  After the carbs are balanced using the Unisyn at the
correct rpm, then the "dog bones" should be adjusted so that they do not alter
the speed, but will "take up" uniformly as the throttle is increased.

> the screw assemblies on the bottom are what is used to
> adjust fuel correct?

Yes

> it does not seem to do anything if I screw them all the
> way up or out. also, does screwing all the up lean the mixture or richen it?

All the way up, leans the mixture.  I've had mine "all the way up" for years,
but still running too rich.  In pursuit of that problem, I recently installed
new needles (M-39).  Now, my Colortune confirms that the mixture is "right on",
but my nozzles are still "all the way up".  My next step is to replace the
nozzles with new ones, in a hope to achieve correct mixture with the nozzles
adjusted about two turns down, giving a margin for adjustment.

Dave
'68 1600
Kailua-Kona

>

Mike wrote:

> hi,
>
> I have adjusted the carbs with the colortune and they are sucking at the
> same rate. my early 67 with dual SU's idles at 1500 right now. it is doing
> so smoothly also. however I am confused on the procedure for adjusting the
> to idle at around 600 per my service manual. the air rate was adjusted using
> the small slotted screw mounted on top of each carb that sits behind the
> damper housing. the screw assemblies on the bottom are what is used to
> adjust fuel correct? it does not seem to do anything if I screw them all the
> way up or out. also, does screwing all the up lean the mixture or richen it?
> I have looked over the 311s.org links but am still a little confused. the
> choke cable is not hooked up. the two carbs are still linked with the bar
> that is connected to the throttle cable.
>
> any ideas on where im going wrong?
>
> thx,
>
> mike
>
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