[T3] Chris's Mentor

[Jim Adney]

On 8 May 2013 at 14:45, Chris Sheridan wrote:

> Hi Ken, what you describe is exactly what I experience every time I have
> set my valves using this method. The 24 degree difference you describe is
> typical when using this method.

I get the impression that you and Ken are working under a couple of 
assumptions:

1) That the marking on the pulley is only approximate and that this 
is a way to get a better TDC.

2) That the position of the dist drive gear has some effect on when 
TDC occurs.

> An important final step when you are at that point, when you have used the
> method I described to find TDC for no.1 and see that notch on the pulley is
> 24 degrees off, is to reach down through the inspection hole and put a spot
> of White paint or White out at 12 O'clock on the Pulley. That paint spot
> then becomes your new 'notch' for timing purposes.  From now on you're
> timing to the Paint Spot rather than the Notch.

This is absolutely wrong. I don't mean to be mean about it, but I 
can't emphasize this enough. Don't do this.

Consider Beetles first: The pulley slides onto the crank, guided by a 
Woodruff key set into the crank. The keyway was carefully cut into 
the crank in a very precise location. Likewise, the keyway in the 
pulley was cut and then the pulley was notched in exactly the right 
place so that TDC will occur when the notch is straight up. Yes, 
there is bound to be some tolerance to this, but it's probably less 
than +/- 2 degrees, not even close to 24 degrees.

On Type 3s, there's the keyed connection between the crank and the 
fan, then the pinned connection between the fan and the pulley, so 
there's probably more room tolerance buildup than on a Type 1, but 
it's still going to be MUCH, MUCH less than 24 degrees.  

So how could you get 24 degrees difference by doing it your way? 
Easy. Look at that video again. Note that the Intake and Exhaust 
overlaps are not symmetrical AND the intake and exhausts lifts are 
not the same, but your method assumes symmetry of both. This puts you 
WAY off from true TDC.

If you really want to find your true TDC, remove a spark plug and 
stick a screwdriver down there. Watch how it moves as you move around 
the OE pulley mark and how it moves near your new mark. Because the 
piston is actually moving so little right at TDC, it will be hard to 
feel there, but at your new mark it should be obvious that you're off 
to one side of the TDC that you're after.

Yes, in a previous email I agreed that your method worked, but  only 
to tell the difference between #3 TDC and #1 TDC. I never dreamed 
that anyone would try to use this to improve on the pulley marking.

As far as the dist drive gear goes, the only reason there's a 
preferred position for it is that it allows you to install the 
distributor without the vac can hitting anything. If there was 
nothing in the way and your spark plug wires were long enough, you 
could install the drive gear any way you liked and make everything 
work perfectly.

And even with the drive gear removed, TDC and the valve timing will 
be unchanged.  

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