[alanb]

What is the correct spark plug gap? Also my plugs are black so I assume I am running rich, how do adjust air/fuel? Does the choke increase idle speed by running rich? Thanks

 

[Roadman]

Hi Alan------------The correct gap for Z plugs is around .044. That's assuming the engine is in stock condition and is not turbo or supercharged or equipped with a "hot" ignition system. If the plugs are dry and black, this indicates fuel fouling from a too-rich condition. If they're wet and black, oil fouling is the cause. If you're running the stock '74 flat top carbs, you will probably have difficulty setting the fuel/air mixture ratio. The standard suggestion here is to swap the stock carbs for '70 to '72 round top SU carbs. And finally--yes, the choke increases idle speed by richening the mixture. Hope this helps.

Roadman

 

[steve 260z/300zx]

You didn't mention which carbs you are using but...

On the early sus, the choke linkage will both increase throttle plate opening and enrichen the carb as it becomes fully engaged.

 

[steve260]

correction...

Note:

The gap is .031 to.035 for a 74 z.

Steve