Kidnova

Hey Rags, What's up?

ragtop409

not much cant wait to get my resin bucket in the water and test my mod's out. Is it summer yet?

rag's

Kidnova

Nope. Not summer here....sucks. What mods did you do? Still have the Nova?

blue thunder

I've never tried it, but have read where marine carbs are factory calibrated differently to account for the increased negative pressure created in the float bowls due to the positioning of the j tubes relative to the airstream. Makes sense to me. Maybe this can be tuned out with different idle screw adjustments or float level changes, I don't know. Anyone?

BT

mcollinstn

Anything you do to a motor, it's exhaust, the carb, the flame arrestor, the engine compartment vents, the air temperature, or the humidity will affect the carb calibration in some manner.

Most tiny changes will go unnoticed.

The J tube deal will indeed create a higher negative pressure in the bowls with increased airflow. What I mean by that is that at idle there will be no change - at WOT there will be a bit of negative pressure in the bowls in comparison to the standard slash cut vents. This will in some cases require a fatter main jet.

Float level change affects calibration all the way across the operating range - keep a normal float level. Possible main jet changes, though.


Like any carb change or engine mod, you gotta check (the plugs) and tweak.

But you need J tubes in a boat. No 2 ways around it.

blue thunder

I would ask them what they planned to do for calibration changes to account for the float bowl pressure change. If it is nickerson you are using, maybe they have a tried and true calibration change that negates the affect. Whatever you do, just make sure you fully lube the kunuter assembly before returning to service

BT

Kidnova

Dave, thinking about selling the ZZ carb and buy a marine carb from Eagle as you suggested before. That way I'm out only a couple hundred $. However, I know Nickerson has a good reputation and feel that if I give them all the specs on the ZZ they'll set the carb up properly. Not sure about an "off the shelf" carb out of the box being set up right for the ZZ.

Boating season will be here in a month or so, gotta make a decision. Hate these executive decisions

blue thunder

Life was certainly easier back in the day when the kunuter was in charge of all decision making

BT

Kidnova

LOL. I got married 8 years ago. The Kunuter stopped making the decisions 7.5 years ago.

Kidnova

mcollinstn brings up another good point re: future exhaust changes. No doubt I'll be dicthing the stock Merc stuff and probably be putiing on the Revolution Marine manifolds. Don't expext a huge gain from that, maybe somewhere in the +100 to 200 rpm range. But that combinded with the J installation will add to the mix. Maybe best to feed all the info to Nickerson and let them have at it. What do you guys think??