I do not know where the distributer should be as far as mechanical and vac advance. Can anyone help? My distributer is at 1000 rpm, my initial timing is at 10 degrees.At 1500,10.5 degrees, at 2000 rpm is at 19 degrees, at 2500 its at 20.5 degrees st 3000 its at 21.5 and at 3500 its at 21.5. This is with the vac advance unplugged. With the vac advance plugged in, I am at 1000 rpm, 35 degrees, 1500 36 degrees,2000, 45.5 degrees, 2500 46,3000 47 and 3500 47. Is this curve even close? This is a fresh rebuild on the 403 with 9.06:1 compression and a Comp cam advertised duration of 265 intake and 273 exaust. part # 42-208-4. I am having a terrible time tuning this.

 

If you initial timing is at 10BTDC with vacuum unplugged you are pretty close to the stock setting for most Olds engines. I couldn't say whether the curve sounds correct or not although the total sounds a little high. I have heard people talk about the mid thirties for total advance. Here's hoping someone will know the answer...