If you have an "advance" timing light use the bottom mark. Otherwise
use the 4th mark and then go up a little as that's 16 degrees.
If the dwell moves around after you change the points it may be a wobbly
distributor shaft.
Mike
----- Original Message -----
From: "Ken Pearce" <ken__pearce@hotmail.com>
To: <datsun-roadsters@autox.team.net>
Sent: Monday, June 04, 2001 2:36 PM
Subject: Tuning questions, dwell, timing, SU rough idle?
> So I bought a Sears $49 Tach and Dwell diagnostic meter to go along with
my
> $79 Sears timing gun. I'm very happy with both! I hadn't checked my
timing
> for over a year now and since my tach went out, had no idea of what RPM my
> engine was idling at.
>
> I have a pre-smog recurved distributor in my 68-2000 and had set the
timing
> to 16 degrees last year after the engine rebuild. Yesterday, it was dead
> on, still 16 degrees at 750 rpm.
>
> The dwell setting is at 50 but it moves around a little. I took the
> measurement with the vacuum advance tube removed from the dist. Is that
> correct? Do I need to plug the hole on the dist for the vacuum adv when
> taking a dwell measurement?
>
> The manual for the tach/dwell meter says to take a dwell reading, then rev
> the engine to about 1500 rpm and then back to idle. It says that if the
> dwell reading varies by more then 3 degrees, then the points need
replacing.
> Now I can't figure out if they are saying to take the second dwell
reading
> at 1500 rpm or after it returns to idle? When at 1500 rpm's, the dwell
> meter is pegged and goes off scale past 90 degrees.
>
> Points are easy to change and cheap so I'll go ahead and change out the
> current set. I'm just looking for a little insight as to what the dwell
> readings mean.
>
> Also, I'm using the first (lowest) mark on the crank pulley to set the
> timing. What are the rest of the marks for?
>
> Are SU 2000's known for their rough idle? Seems like I heard a comment
> about that at Shasta last year about SU's "shaking you to death". I
wonder
> if I replaced the original coil with a newer higher-output model if that
> would help?
>
> Another question, though unrelated to tuning. I have gas pooling in the
> little dimple between #3 and #4 cylinder on the intake manifold. I can't
> figure out where it's coming from??? Possibly the plug in the manifold
> where the smog equip used to be??? Anybody seen this before?
>
> Thanks in advance,
>
> Ken Pearce 68-2000
> Bellingham, WA
> _________________________________________________________________
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