Quick question regarding base timing and advance on 3.9 in a 95 Range Rover Classic.

Why are the timing and advance so conservative? In my experience base idle timing can be anywhere from 5-10 degrees and increases with engine speed to 20 or more. The Service Manual specs call out a base idle timing of 5 degrees with a max advance of 8.5 at 2200.

Very curious to learn why this is? Thanks.

 

I suppose when all the engine parts are new the 5 degree mark may be fine...but as things wear some the base timing may need to be closer to the 10 degree mark.....thats a common old V8 trait. I use the old trial and error method of timing the older engines..keep advancing the timing a little bit at a time untill you get spark knock when you are under accelleration...then back it off some to the sweet spot.....a lot of these will be around 9 degrees if you feel the need to measure it.
one note of minor concern >>>you will notice that as you advance the timing the engine idle speed will pick up, and at first the IACV will be able to compensate.....after a while it wont and you may be idling slightly faster than the the factory specs....which actually is no big deal, unless you are a 14CUX ecu.....then you throw a 48 code .....personal experience

 

Yep. I had to do the same to my Classic. 5 degrees is nowhere close to the right spot.
I basically set it by a light then did it by feel and ear until it was right. My timing chain is super tight and I'm pretty sure this engine has been rebuilt at some point.