Timing on fuel injected bug?

I just replaced the points and condenser with a Hall effect "Hot-
Spark" upgrade for Bosch distributors. The car is a 1978 Cabriolet
with a double acting vacuum advance. The sticker in the engine
compartment says to set the timing at 5 degrees after TDS at idle.
When I do this assuming the single mark on the pulley is TDS the idle
is rough and the performance poor. By trial and error I usually end up
setting it somewhere around one degree before the pulley mark.
Does anyone know for sure if the pulley notch is TDS? I assume VW
went to the double vacuum system to meet emissions requirements in the
'70s. Any comments will be appreciated.

By the way, I am impressed with the Hot-Spark system. With even new
points the timing mark would bounce around a bit under the strobe
light. With the Hot-Spark it is rock solid and there has not been a
single miss fire since the upgrade.

total advance is what?
IIRC I think my '76 had a single vacuum unit but it was not from Ca.
Is your push/pull vacuum unit working correctly?

I would think if the pulley only had 1 mark, it would be TDC and I cannot
recall ever seeing one of those.


"2ndKnight" > wrote in message
...
>I just replaced the points and condenser with a Hall effect "Hot-
> Spark" upgrade for Bosch distributors. The car is a 1978 Cabriolet
> with a double acting vacuum advance. The sticker in the engine
> compartment says to set the timing at 5 degrees after TDS at idle.
> When I do this assuming the single mark on the pulley is TDS the idle
> is rough and the performance poor. By trial and error I usually end up
> setting it somewhere around one degree before the pulley mark.
> Does anyone know for sure if the pulley notch is TDS? I assume VW
> went to the double vacuum system to meet emissions requirements in the
> '70s. Any comments will be appreciated.
>
> By the way, I am impressed with the Hot-Spark system. With even new
> points the timing mark would bounce around a bit under the strobe
> light. With the Hot-Spark it is rock solid and there has not been a
> single miss fire since the upgrade.

Thanks for the response dave. I will test the vacuum advance.

From searching this forum others say that VW did some odd things with
their timing marks especially in the late bug years. Some pulleys had
two marks, some with one at TDC, and some (with the double vacuum
advance) with one mark at 5 degrees ATDC. From the way mine behaves I
think it is the latter.

I really have not seen a pulley without a TDC mark. Usually the pulleys
will have more than one mark, a mark for TDC and ones for timing the engine
either BTDC or ATDC.
The marks can be a sharp 'V' or a smooth "U" usually.
At least that is what I am used to seeing. ;-)

Of course when I see some CA cars, I always see uncommon things on those
engines! lol

"2ndKnight" > wrote in message
...
> Thanks for the response dave. I will test the vacuum advance.
>
> From searching this forum others say that VW did some odd things with
> their timing marks especially in the late bug years. Some pulleys had
> two marks, some with one at TDC, and some (with the double vacuum
> advance) with one mark at 5 degrees ATDC. From the way mine behaves I
> think it is the latter.