[T3] Weird Idle Dips

[Jim Adney]

On 23 Feb 2012 at 21:05, Chris Sheridan wrote:

> On this subject, I've had an annoying problem in that every time I do a
> tune up (points, plugs, cap, rotor, condenser and valve adjustment), my
> idle is smooth and clean. After a few weeks it starts to have a weird stall
> dip at red lights. Only longer lights. Then by the next month, my idle at
> stoplights becomes rougher, with a more frequent miss in the idle, until
> I'm tired of it, then I do a tune up again and get the smooth idle. Is
> there any relief or escape from this creeping miss problem, or is this just
> the way the cookie crumbles?

First off, buy Bosch parts, then never bother changing the cap, rotor 
or condensor again, Just points and plugs, if and when they need it.
The rest of the parts are likely to last forever.

When you do your tuneups, do you find that the timing has changed? My 
bet is that if you look at the cam in the distributor you'll see that 
it's worn and rough where the points rubbing block rubs against it. 
This wears the rubbing block rapidly and causes the dwell and timing 
to go bad quickly.

When I refurbish a distributor, I clean up the cam so this won't 
happen again, IF you take care of the cam in the future. To care for 
the cam, you should wipe it clean at every tuneup and then apply just 
a touch of fresh grease to it. If you don't do this, accumulated grit 
will cling to the rubbing block and grind into the cam.

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