Where is 5 degrees ATDC?

[Patronus]

My '74 2.7 CIS must be set at 5 degrees ATDC at idle, according to my workshop manual. Is this to the left or the right of Z1? It must be left, I think, but I just want to make sure.

Over the past months I have played around with the timing a lot, and I noticed that the engine easily stalls when set at TDC and even more so at 5 degrees BTDC. Very annoying. For quite some time I had it at about 10mm to the right of TDC, however many degrees that may be. I realised that it gave me nice torque at low rpm, at a slight loss of high-rpm power. More driveable, though.

But I want to set it at 5 degrees ATDC again, as the book indicates. Why would my engine stall so easily when set at 5 degrees ATDC? It literally has no power below 1500rpm, and I really have to juggle revs and clutch it to get it moving. It just doesn't feel right.

Also, why does the 'Z1' on the flywheel differ from the 'Z1' on the pulley by about 30 degrees? Should it be like that? (I have a 901 gearbox and the corresponding flywheel, since body was a 912).

Thanks in advance

[Jim Sims]

Patronus, Use the search function. The following was found by specifying "pulley AND Z1" and was "lifted" from an "Early_S_Man" posting. "The marks are in two 'groups' on the engine pulley, if you rotate the pulley clockwise until the first three marks are to the right of the notch on the fan houding, are: Aligned at notch, 5 degrees After Top Dead Center, slightly to the right,Z1, Top Dead Center, and a ways over to the right, 30 segrees Before Top Dead Center, and slightly to the right, 35 degrees Before Top Dead Center.

There are two basic checks, one at 900 rpm idle with the vacuum hose ATTACHED, where it should be 5 degrees After Top Dead Center (ATDC), and very briefly, with vacuum hose DISCONNECTED at 6000 rpm, where it should not exceed 38 degrees BEFORE Top Dead Center.

If setting the timing does not improve the situation dramatically, I suspect you need to remove and clean the distributor very thoroughly, including disassembly of the point plate, and centrifugal advance mechanism to be sure there are not rusted, stuck, or broken springs causing the centrifugal 'curve' not to occur smoothly. Any jumpiness or stalling of the timing mark at a certain rev range or spot is a clear indicator of advance mechanism problems!"

Cheers, Jim