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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.

Reply to
2ndKnight
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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.

Reply to
One out of many Daves

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.

Reply to
2ndKnight

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

Reply to
dave AKA vwdoc1

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