[T3] Vacuum advance can

[Jim Adney]

On 4 Sep 2024 at 19:02, Doug Brashear wrote:

> Jim A's selection of spares (or rebuilding services) to the rescue again!
> Dan, please post an update after you install the new can...I'm interested to
> hear if it helps any of the higher speed surging that I experienced when I
> had the car. 

The vacuum advance on the FI distributors only works to slightly improve 
gas mileage at crusing speeds. The mechanical advance does all the heavy 
lifting, but if you're having problems with poor running off-idle, it's worth 
checking that the mech. adv. is actually working. They sometimes seize up.

To check the mech adv, grab the rotor and twist CW. Ignore the free play. 
There should be some spring loaded CW motion that will snap the rotor back 
if you release it.

If you remove the rotor, there will be a felt plug in the hole in the top. Add a 
couple drops of motor oil to that felt at each tuneup to keep those parts 
working freely. Engines that are vacuum advance only, like all the early carb 
engines, will have a blind hole, no felt, and no need for oil.

While you're in there, wipe off the ignition cam and add a very thin layer of 
grease to it. That grease will collect abrasive dirt over time, which will wear a 
groove in the cam, so that's why it's necessary to remove the old, dirty 
grease and relube regularly. Clean off the rubbing block on the points at the 
same time.

If you're having problems that you think might be related to the distributor, 
consider sending it to me to be rebuilt. There are several things that will 
likely benefit from readjustment in this process.

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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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