[Brian Baker]

I didn't look at the directions, will do so tomorrow. I do know for fact that any of the 3 retard wires that aren't being used need to be grounded. I think this is the case for the violet wire (20 degree retard for starting) as well.

There are a few good reasons for locking out the mechanical advance when using this retard box.

First and foremost, it makes it easier and more consistent when dialing in the retard for whatever amount of nitrous you want to run. Having the mechanical advance functioning in tandem with the retard in the box can have the actual timing "all over the place". This can be a problem under a nitrous load until the engine reaches an rpm where the mechanical advance is in full.

Another reason is throttle response. I have mine locked at 36 degrees. The throttle response from idle is awesome.

Third, when checking the amount of retard in the box with a timing light, if the mechanical advance is locked out, you don't have to rev the engine to 3000 rpm or so to do it. Just check it at idle.

I'd lock out the mechanical advance. It will make dialing in the timing retard easier, and more consistent. Not being consistent when using nitrous is what hurts parts.

Pull 2 degrees of timing out for every 50-HP of nitrous, plus 1 degree. In other words, if using a 150-HP shot, pull out 7 degrees. This is being conservative and won't hurt parts from too much timing lead. You can tune it later, but use this as a baseline.

Keep an eye on fuel and bottle pressure. I'm still in the learning stages myself, but I know enough right now on how to make power with nitrous conservatively and not hurt parts. If you need any tips on dialing in the fuel pressure or bottle pressure, let me know.