Type Three Tuning Page -- Distributor
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> Here's the question, about the condensor...there are two wires coming out of the condensor (that's normal), and one of those connects to the breaker
> points. Ok, well, in order for the wire from the condensor to connect to the wire from the points the condensor wire has a little rubber
> "stopper" or whatever you want to call it that is supposed to seal the hole in the side of the distributor. My problem is that the "stopper"
> piece, isn't tight enough in that hole, therefore, it doesn't seal and it doesn't even hold the wire in place!! What do I do?
Up through 71 there was a clamp built into the condenser mounting bracket that held that plug in place. Starting in 72 they switched to a separate clamp part, which your dist is apparently missing.
You have 2 choices: Either find one of the 72-3 clamp pieces and install it with the screw that goes in the hole under where the plug goes. Or buy a 68-71 condensor and use the clamp that is part of its bracket.
Jim Adney, jadney@vwtype3.org
Madison, Wisconsin, USA
> I was wondering if someone could explain to me the (mathematical?)
> relationship between timing and dwell. Meaning, if dwell is reduced, does
> the timing advance or retard? What the heck is "dwell" anyway? I did an
> archive search but nothing came up (which means the archive/search tool
> might be broken, as this is a pretty basic search term!)
Timing determines the moment that the spark fires. Dwell is the amount of time
(expressed in degrees of distributor shaft rotation) that the points (or their
equivalent) are closed.
The spark is triggered when the points open. Nothing happens (sparkwise) when the points close.
The spark happens when the points OPEN and it lasts until the stored energy in the coil is
exhausted. The length of time that the spark lasts is generally quite short compared to the
time between opening and closing of the points.
In a standard coil ignition system the points need to be closed for some amount
of time before they open so that sufficient energy can be stored in the coil.
This is because the coil is an inductor and the current thru it rises only
slowly. If the dwell were too short, the current would still be small when the
points opened and the spark would be weak. The dwell is generally set at a
number that means that the points are closed a little more than half the time.
In a 4 cyl engine this 50% duty cycle gives us a 45 deg dwell. In a 6 cyl this
is a 30 deg dwell, and in an 8 cyl this is 22.5 deg. On a car with points it is
important to keep close to the 50% point, so that the points are opening when
the cam is at it's fastest rate of rise, but with an electronic switch the
dwell can be longer because the points are no longer a consideration.
In general, if you need to set the dwell, you must do it first, because
changing the dwell changes the timing. Increasing the dwell retards the spark. Once
the dwell is set you set the timing. On your <other> car you make no allowance
for the changed dwell. You set the timing exactly where it is supposed to be.
Do not attempt to correct for a different dwell by changing the timing; no
correction is necessary or desirable.
--
Jim Adney
...Make sure the distributor drive gear is in right for a T-3. A lot of shops install
them from habit for T-1.
> Forgive my ignorance here, but what's the difference here? Is it 180
> degrees off?
No, it is about 90 degrees off. And you shouldnt just move the wires
around because of the timing offset on #3 cylinder.
--
russw @ www.classicvw.org
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