Here's an easy way to tell, if you have a timing light. Connect the
timing light and watch the timing marks on the harmonic balancer
(crankshaft pulley) advance as you increase the engine speed from idle
to about 3000 rpm. If you have a smog distributor, you will see about
30 degrees of advance. If you have the early (non-smog) distributor,
you will see about 16 degrees of advance. Each little notch on the
pulley is four degrees, by the way. The big notch is at zero degrees
before top dead center. This is true for the U20. I don't know how the
R16 timing marks work. But the timing is the same for both engines.
You may have to make some additional marks on the harmonic balancer at 4
degree intervals to see what is really going on, if you have a "smog"
distributor and your idle timing is set anywhere before zero degrees
Before Top Dead Center.
Ignition timing works this way: on the original design, the engine was
intended to be timed at 16 degrees before top dead center at idle. It
needs a total of about 30 degrees of advance at operating speed (around
3000 rpm and above), so the distributor was designed to add another 15
degrees of advance as engine speed increased from 800 rpm at idle to
3000 rpm and above at operating conditions. In 1968, Nissan changed the
idle timing to zero degrees BTDC in an attempt to reduce "smog". Of
course, it was then necessary to increase the distributor advance to 30
degrees in order to get the proper total advance (30 degrees) at
operating speed. Timing to zero BTDC does reduce certain emissions
components, but it also makes the engine overheat, and idle at zero BTDC
is crappy at best. So, many owners of "smog" (30 degree) distributors
set their idle timing to some value above zero BTDC, in order to get a
decent idle and avoid overheating. Unfortunately this causes the
operating speed timing to be too far advanced, which leads to detonation
and all kinds of other problems. The solution is to rebuild your
distributor, if it hasn't already been done, with 15 degree centrifugal
advance weights and cam. For "smog" checks, you can always retard the
timing to 0 degrees, if you can get it to run there.
Barrie
'66 2000
San Diego
-----
The Belgian Roadster wrote:
>
> Thankst to Mike!
> But, my car has been imported from the States, with emission control
> already removed.
> How can I recognize if the distributor modifications have already been
> done?
>
> Chris,
> The Belgian Roadster
>
> -----Ursprüngliche Nachricht-----
> Von: "datsunmike" <datsunmike@nyc.rr.com>
> An: "The Belgian Roadster" <chriss@euregio.net>
> Gesendet: Sonntag, 27. August 2000 04:31
> Betreff: Re: Pre-emission Distributor Part Nos.
>
> > Chris,
> >
> > It won't run right and it will overheat w/o the internals/timing of
> the
> > early distributors. The later distributors have alot more advance
> timing in
> > it and can cause the cars to run hot. Don't ask me why as I don't
> know why,
> > but everybody suggests that after removing the pollution equipment
> to use
> > the 7.5 assembly cam and the springs.
> >
> > Instead of timing the later cars at 0 you can time the cars at 15
> BTDC with
> > the correct advance.
> >
> > 66 Mike
> > ----- Original Message -----
> > From: The Belgian Roadster <chriss@euregio.net>
> > To: datsunmike <datsunmike@nyc.rr.com>
> > Sent: Saturday, August 26, 2000 2:59 AM
> > Subject: Re: Pre-emission Distributor Part Nos.
> >
> >
> > > Hi,
> > > Why modify the distributor, when emission control has been
> removed?
> > >
> > > Chris,
> > > The Belgian "online" Roadster
> > >
> > > -----Ursprüngliche Nachricht-----
> > > Von: "datsunmike" <datsunmike@nyc.rr.com>
> > > An: "Paul" <9laser3@bright.net>
> > > Cc: "Datsun Roadster List" <datsun-roadsters@autox.team.net>
> > > Gesendet: Samstag, 26. August 2000 03:02
> > > Betreff: Pre-emission Distributor Part Nos.
> > >
> > >
> > > > To make a emission distributor into a pre emission one use the
> > > following
> > > > nos.:
> > > >
> > > > Assembly Cam - 22132-14605
> > > > Weight Governor (2) 22109-71300
> > > > Set Spring 22110-14600
> > > >
> > > > I would also suggest changing the Vacuum Advance plate also -
> > > 22136-H2301.
> > > >
> > > > All the bits were about $30.
> > > >
> > > > 66 Mike
> > > > ----- Original Message -----
> > > > From: Paul <9laser3@bright.net>
> > > > To: datsunmike <datsunmike@nyc.rr.com>
> > > > Sent: Thursday, August 24, 2000 8:58 PM
> > > > Subject: Re:
> > > >
> > > >
> > > > > So you've been to Ohio before!
> > > > >
> > > > > Paul
> > > > >
> > > > > -----Original Message-----
> > > > > From: datsunmike <datsunmike@nyc.rr.com>
> > > > > To: 9laser3@bright.net <9laser3@bright.net>
> > > > > Date: Thursday, August 24, 2000 7:44 PM
> > > > > Subject: Fw:
> > > > >
> > > > >
> > > > > >This is for you Paul!!!!!!!!!!!!
> > > > > >
> > > > > >Mike
> > > > > >
> > > > >
> > > >
> > > >
> > >
> >
> >
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