No Timing Marks on CU Air Cooled

[sweller]

My 1981 2.0l air cooled CU engined van doesn't seem to have any timing marks on the crank pulley. I've carefully checked both front and back of the pulley for a notch or dimple or am I missing something obvious? I've fitted a timing scale (it didn't have one when I got it).

It runs and idles ok but does run out of puff quite quickly when climbing hills - I wanted to check that it was advancing/retarding correctly but I can't even check it's timed right!

I have been told that it wasn't unusual to see pulleys without marks, so how the hell has anyone timed it accurately for the last 33 years?

Any ideas?

[bigherb]

The mark should be on the rear rim of the pulley it is very small. It is only missing if someone has fitted a pulley from a early Type 4 car engine where the timing mark is on the cooling fan.

[sweller]

How odd...

Where is the TDC mark in relation to the cutout in the centre of the pulley (the one the 3052 crank turning tool fits into). Say if the centre cutout is at 12.00 O'clock where's the TDC mark?

It may help with the hunt!

[bigherb]

Like this set on TDC. The picture is taken at an angle, the cut out doesn't line up exactly with 12 deg as in the picture.

[sweller]

Right - that's very, helpful. Thanks.

Whilst I was mucking about trying to find the TDC mark earlier today. I noticed a blob of paint (which I initially thought was a drip from the respray) which when under the strobe came in at 10 deg BTDC. When I pulled No 1 spark plug and watched the piston and with the aid of a screwdriver to determine the physical TDC the blob of paint was at the TDC mark. I suspect a PO had similar troubles but had timed it to 7.5 deg BTDC.

I timed up the van to 4 deg ATDC as per the Haynes manual for electronic ignition models (the idle stabiliser has been removed on mine and the wires permanently joined). Runs OK but still struggles on hills.

But back to your picture, when I line it up TDC it looks like this:



Not far from your image - given all manner of inaccuracies thrown in through parallax, the physical TDC being not quite right etc. The white mark is chalk, the blob of paint is yellow.

Can't find a physical notch though. Opinions?

[bigherb]

It's looks like it's taken about the same angle as my picture. If you look at it square on it looks to line up nearer 8 deg.

Does your engine have a hole here.


Originally the engine was timed through the hole with the TDC mark in the fan housing and the timing marks on the fan.


Your engine may be an amalgamation of bits.