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Re: [T3] response from Jim Adney re jerky acceleration


On 26 Sep 2005 at 16:40, Chris Wright wrote:

> My responses are below in caps.  Unfortunately,  out of these good 
> suggestions, I've tried all except the dizzy cap which I have on order 
> from Bosch.

I was afraid that you'd already done all these rather obvious things, but 
thought it was worth mentioning. How about the condensor? I've never seen a bad 
Bosch one, but have you tried a replacement? 

I'm not familiar with the early distributors, but if there's a wire in there 
that flexes as the dist advances, you should consider the possiblity that the 
wire itself is broken under the insulation. I've seen that happen, and you can 
only tell it by pulling rather hard on the wire to see if the insulation 
stretches and breaks.

> Additional info, if you think it's still possibly  ignition, the advance 
> is as per the specs for the dizzy, with max 11degrees of vacuum advance 
> and 17 degrees of centrifugal advance at 4200rpm.

I don't think that details of the advance curve will cause your symptoms. It's 
rather common for the mech advance to be frozen up completely, but this only 
results in very poor power. There are lots

>> >On 26 Sep 2005 at 10:02, chris wright wrote:  
> >
> >>You can imagine it best by imagining accelerating on a very bumpy road so
> >>that the car jerks over the bumps.

> >To me this sounds more like ignition "miss" than anything else. I would be 
> >looking at ignition problems.

> I'VE FITTED A NEW BOSCH SET OF SILICON LEADS AND CAPS AND ALSO TRIED 
> SUBSTITUTING A COPPER CORED LEAD INTO EACH CYLINDER IN TURN.  - NO CHANGE.

Unless this wire set has the right angle connectors on the dist cap ends, there 
is some chance that they will arc over to the engine cover. You might check 
this by seeing if the problem persists if you drive without the engine cover.

> >Check the cap, inside and out, for dirt, carbon tracks, and moisture.

> IT'S CLEAN AND NO APARRENT DAMAGE, BUT I'VE ORDERED A NEW ONE.  I'M 
> STILL ON THE ORIGINAL SO THIS IS STILL A POSSIBILITY.  GETTING ONE FOR A 
> 64 ONE YEAR ONLY DIZZY IS NOT EASY!

The Bosch caps seem to last forever. In general, I only see them damaged when 
abused, never just from use. Is the carbon contact inside the top center still 
there, protruding and spring loaded?

> I'VE NOT USED IT IN THE RAIN LATELY AND IV'E DRIVEN TO WORK SEVERAL 
> TIMES IN THE SUN, A 40 MILE EACH WAY TRIP.
> THE PROBLEM GOES AWAY COMPLETELY AFTER ABOUT 30 MILES OF MIXED DRIVING 
> BUT COMES BACK WHEN NEXT ITS RUNNING COLD.

It need not be rain. Just dew can cause problems, but the worst are cold damp 
mornings, during or after a rain, when the humidity is 100% and every surface 
of the car is covered with dew. It's there, even though you don't notice it.

I wonder if another possibility is that what you're feeling is a slight 
pinging. Have you tried higher octane gas? Upping the displacement from 1500 to 
1600 would also up the compression ratio a bit, and this could be blindsiding 
you.

BTW, it's best not to change the subject line within a thread. This helps keep 
all the different responses together. It looks like you've fixed your "Reply 
to:" setup; thanks, that helped.
 
-- 
Jim Adney
jadney@vwtype3.org
Madison, WI 53711-3054
USA

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