I have the correct Lucas distributor (DMBZ6A-40576A) for my 3.4l XK150. The advance arm on the distributor cam is stamped 25 degrees which with the static timing give a total advance of over 50 degrees at the crank. This seems excessive compared with a total advance of ~34 degrees in most other cars. Does anyone know if this is correct for my car? Also, does anyone have data on the advance timing curve for this car? Thanks.

Submitted by mfrank@westnet.com on Wed, 05/19/2004 - 18:54

He got them from from the distributor, just like he said.

Since we're talking about four cycle engines, the distributor rotates at half the speed of the crank. So 25 degrees of distributor advance equals 12 1/2 at the crank. In the event that you are correct about initial and vacuum advance totalling 16, then you have 28 1/2 at the crank. I suspect that the total is really in the low 30's, check the books for accurate static and vacuum numbers.

Submitted by bonnettoboot@e… on Wed, 05/19/2004 - 18:27

Bruce, where did you get those figures? The static timing is 6 deg BTDC. The vacuum advance is a max of 10 deg and the centrifugal is 15-17 deg for a total of 33 deg at full speed!

Jaguar affectionado and etc.