I have a carb stumble just off idle

 

???

You have a carb... And it stumbles just off idle? What does that mean?

FS

 

I was gonna say you might need to adjust your AP, but edited the responce 'cause they rarely "unadjust" themselves. If the carb has never been rebuilt, you may need to do that. It sounds like :
1) The diaphragm has gotten old. This can mean either too tough to work very well, or it has a crack, and is'nt pumping the full monty.

2) There's a stuck checkball in the AP system, allowing no pump shot at all.
The latter is usually noticable throught the RPM range any time you try to step on it.

 

Is it adjusted the same as a holley, with .15 clearance at the end of the stroke

 

Nikki carb?

 

yes

 

No. Adjust the nut till it shoots immediately when the throttle is open, just dont go too far or youll reduce the pump shot. But like Sterling said, they dont generally go out of adjustment, so if you havent messed with it, then you may have another problem.

 

Forget the Holley carb. Different animal.

In my experience, the best starting point for the stock Nikki AP is as follows:
There is a lever that fits into the AP housing cover that actuates the diaphragm. The cover has a slot through it, and the lever is pivoted with a pin in that slot in the housing.
The outside edge of the part of that lever that is pivoted in the housing sits proud of the housing cover just a bit.
When the AP is adjusted to maximum shot, the top half of the vertical edge of the lever sticks out because the lever sits in the idle position at an angle.
When the AP is adjusted for a very small shot, it sits in a bit for the same reason.

The best starting position is for that part of the lever to be parallel with the housing.

For an unmodded carb, you should not need to adjust much past 1-1/2 turns either direction...more likely towards the bigger shot than towards the smaller.
But that's where I set my carbs to- even my modded AP carbs.

Is any of that unclear?