How do I know which 1.5 timing setting to use? There are two

[rumbling_caddy]

I have a 1.5D engine with the original injection pump.  Not sure where to look for the "yellow dot"
Initial IP timing was set at 1.00mm, but it felt weak.   I bumped it up to 1.20mm and it feels better,
but I'm not sure if Im over doing it.

From Vincent excelling IDI injection timing guide:

    Early Chassis:  (1977-1983)

    1.5l non-turbo 1977-1980                                        0.88 +/- 0.05 mm

    1.5l non-turbo 1980 with yellow dot                         1.15 +/- 0.05 mm

[RabbitJockey]

There will be yellow smeared all over the lower timing advance piston cover on the front side of the pump.  It sounds like u have a yellow for pump tho,  what's the part number on it?

[burn_your_money]

If it's not clacking like crazy you got it right.

[rumbling_caddy]

There will be yellow smeared all over the lower timing advance piston cover on the front side of the pump.  It sounds like u have a yellow for pump tho,  what's the part number on it?

Can't see any yellow paint anywhere but the 1.5D is running better at 1.20 and not clacking like crazu

[fatmobile]

Then advance it a little more.
 They are just numbers, might as well scribe a mark and use that as a referance.

[RabbitJockey]

checked an old vw diesel parts thread, and hagar says 107a is the correct number for a yellow dot pump.  and like everyone else says if its running good where u have theres no reason to change.