Another timing question

[zukinut]

Just wondering why you set youre timing with the motor at 2000 rpm and not at idle, or at 1500 rpm. I know there is a reason, and i set mine at 2k but im curious as to why you do it that way.

Will

 

[Agnem]

The reason is that you need to build up sufficient fuel pump presure (and this is internal IP pump presure, not what's coming from the feed pump) to overcome any external influence from the timing advance cam. The advance piston needs to be 100% influenced by pump presure. Now, this external influence does go away just before 1400, which is why that is the luminosity timing RPM. The luminosity method has enough trouble trying to watch strobes at that speed, yet alone 2000. Why they settled on 8.5 at 2000 for the pulse method, I'm not clear on, but I can tell you that 100 RPM does make a difference when your in the low timing numbers.

 

[zukinut]

Is it beneficial to retard or advance any more or less than 8.5.

 

[Agnem]

Not usually. A slight advance may be beneficial for those running a high percentage of WMO, but your glow plugs will suffer. Retarded advance has no benefit.