[John Rogers]

If you are laying across the trunk looking down into the timing hole, when the engine is running, the fan blades move from right to left across the hole. So, to simulate this you can reach down and pull up on the right side of the fan and as the engine rotates you will come to the first timing mark which will be the ADVANCE mark then several blades later the next mark which is the TOP DEAD CENTER (TDC) mark. So you are correct in figuring the marks to the left are the BTDC marks and are where timing is set when full advance is in. The total advance depends on the car and the type engine. For example, in my race car I use 34 to 36 degrees total, a little more than stock, but on the stock 2l engine I use exactly what the specs call for. Good luck.