6.9 with 7.3 IP. Timing spec the same?

[dansvan]

If you had a 7.3 IP on a 6.9 would you still set the timing the same? 8.5 degrees?

 

[icanfixall]

Yes. The pump does not determine what the timing should be from motor to motor.

 

[dansvan]

Thanks, Dan

 

[93_E_350]

If you had a 7.3 IP on a 6.9 would you still set the timing the same? 8.5 degrees?

The 6.9 and 7.3 can use the same numbers. Using a pulse adapter you would want to be in the 8.5 to 9.5 degree BTDC range. Using a luminosity style probe you would want to be in the 1 to 2 degree ATDC range. Basically one meter uses the speed of sound (pulse) and the other the speed of light (luminosity probe) to compare combustion to the timing mark on the damper pulley. Both measurements are accurate just different.

93

 

[Agnem]

In theory yes, but in reality no. The luminosity method relies on the injector to operate in spec. If #1 is weaker than the others, your timing will be more advanced, where as if it is stiffer, then your timing may end up being retarded. Because the pulse method is triggered by the rise in presure from 0psi to anything higher, the timing is actually set by what the pump sends, and not what the cylinder recieves. Having used both methods, I vastly prefer the pulse method for it's reliability and accuracy.