What is this electric cold start looking dealy?

[wolf_walker]

And when does it want 12v?

http://www.evwparts.com/Merchant2/graphics/00000001/068130109R.jpg

[Vincent Waldon]

It's actually not a cold start device (that would need to be on the other side of the pump) but one of the many versions of the "anti-advance" emission control systems... anti-advance because when energized it's telling the pump to stop advancing the timing slightly under specific load conditions... to reduce emissions under these specific load conditions.

Depending on the timing value you set your pump to the engine may run better or worse with this solenoid energized (mine runs better with it not energized, for example) so a bit of experimentation is in order.

For further reading they are documented in the Bosch Yellow Jacket manual.

[wolf_walker]

Huh, that's interesting.

I don't think there is anything on the other side of the pump in the usual advance lever position.
Mine starts alright without cold start so I tend to think Pop's young healthy AAZ
will be ok with it.  If not, any idea if one can stick the advance lever on there?

[burn_your_money]

The advance piston won't have the pin for the advance lever to ride on. So no, you can't just throw one on.
I think Bosch has 2 versions of that "cold start device" They look the same and one wants 12v at one time and the other is the opposite.

[wolf_walker]

Plot thickens eh.. 

I guess if I had a diesel timing light I could tell which it was huh.

[Vincent Waldon]

Yup, but the actual change in timing either way is subtle, dynamic, and only at certain RPMs / load combos.

Hence most folks just trying it both ways and seeing what makes their particular engine run/sound better.

[wolf_walker]

I told Father to check before he mounts it, but is that other forward port on the timing dealy supposed to be plugged?
His photo's it looked open to me.