Itinerant Air-Cooled

1971 Super Beetle with original DVDA distributor. I've always assumed the red notch on the left is the 5 degress ATDC mark to use for setting the idle timing. Is that correct? The Bentley says my pulley should only have that one mark, but there is a second set of marks (but not a notch) in yellow as you can see.

I've always timed those with engine at full advance, 30 deg. BTDC with vacuum line plugged. TDC mark at 0 should line up 180 deg. with another mark on the pulley. I've seen so many pulley notches that don't mean a damn thing, so it's better to figure it out yourself. A protractor can help too.

$12 and an hour - http://a.co/8aeOfIX

$70 and five minutes - https://www.cbperformance.com/product-p/1887.htm

There are so many different pulleys from the various years, that I Do Not Guess, Ever.
Robbie

If you have a T1 engine, a magnetic base, a long screwdriver, and a dial indicator you can use the old pulley to determine TDC. Drill a small spot in the center of the screwdriver handle so that the tip of the dial indicator can sit in it. Put #1 on what you think is TDC. Pull the spark plug out gently. Put the screwdriver into the spark plug hole resting on the piston top. Put the dial indicator and magnetic base on the tin etc so that the tip of the dial indicator sits on the screwdriver. Turn the pulley a tiny bit to either side until the dial indicator indicates you are near TDC. Run the piston down .020" in one direction and mark the pulley with a tiny mark. Now run the pulley in the opposite direction until it drops .020" again. (It will rise back to 0 then fall. Make another tiny mark. TDC will be 1/2 way in between. You can use a protractor or degree wheel printed the same size as the pulley to mark 30 BTDC. All that said - the pulley Robbie linked, or any good Gene Berg type marked pulley will save you hours of fussing around with timing marks. The original marks are really only good if one has all the original parts - carb, distributor etc and they want to set the engine to smog specs.

My 71 Super also had that same pulley setup and the notch was indeed the timing notch at 5º ATDC.

I also timed it at 30º +/- 2º (hoses off and capped) at about 3500 RPMs.

VW distinguished between timing and TDC on the retard-equipped Type 1 engines with a notch for the 5*ATDC position on the inner pulley half and a dimple at "0" on the outer pulley half.

I've not been able to detect the dimple. I will check again.....

In any case, it would seem that notch on the inner pulley is indeed the correct mark to use.