One word? I wish things were that simple.
Well it sounds lean if it backfires through the carbs. I would richen up
the mixture HOWEVER, your piston should thunk a weee bit when raised with
your finger and when let go. Make sure your needles are not binding in your
nozzles. The pistons should move freely.
Also check your float level as that effects your idle mixture making it
possibly richer at idle than when under load and your Colortune will give
false readings as it will be normal at idle and lean when driving.
The oil weight will effect your acceleration mixture slighlty but not under
a constant load as when driving on a highway.
Mike
----- Original Message -----
From: "Amy & Erik" <erikandamy@integraonline.com>
To: <datsun-roadsters@autox.team.net>
Sent: Saturday, September 14, 2002 2:48 PM
Subject: U20 SU Carb trouble
> I am having trouble getting my carbs tuned. Mine have rebushed throttle
> shafts and were recently installed.
> Car is a de-smogged and recurved U20. NOS N-17 needles. Timing is set at
16
> deg
> It idles fine around 6-700. Carbs are balanced.
> I just got a colortune. My spark was blue and slightly orange- though I
> thought it would be more consistent.
> Dashpots have 10w30 in them, move freely but don't make any thunk as they
> hit the bottom. Car is plenty warm and it is 65 degrees outside.
> Plugs are grayish black, and dry.
>
> Runs bad- backfires a bit out the carbs, has no power. Stumbles off
idle.
> Sometimes after it gets past 3000rpm it seems to take off fine, but not
> under load.
>
> I have many, many downloaded instructiuons on tuning SU's (which could be
> part of the problem)
>
> Usually someone from the list can sum up the solution in one word. What
am
> I doing wrong?
>
> Please help.
> Erik Smeby
> 2L 1600
>
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