small bridge 12a/stock nikki

[PercentSevenC]

Originally Posted by sen2two

what do you mean by "play with the jets"? there larger jets for the nikki?

Yes, Mazdatrix carries them. Dunno where you get air bleeds, though. Sterling is the man to ask about Nikki tuning.

Originally Posted by sen2two

can any porting be done to the carb body/Venturis to increase its flow?

Yeah, there are things you can do. Removing the choke, grinding down the throttle shafts, and so forth. Again, get Sterling's advice. Probably be easiest to just buy one of his carbs if this friend is dead-set on a Nikki. It'll help to port the intake manifold, too (but don't make the mistake of port-matching the manifold to the engine).

Even with all that, though, it's going to run out of breath faster than you can say something that doesn't take you very long to say.

Originally Posted by Rogue_Wulff

The stock nikki will not be able to flow enough air to feed even a stock port to it's fullest potential.

Fixed that for you.

Originally Posted by Rogue_Wulff

Using a 4bbl carb, a 1/2 BP will idle without the brappy nature, since it runs off the primary ports until the carb secondaries open. On the other hand, a webber-type 2bbl will have the diminished idle and driveability commonly associated with a BP engine.

You'll still get some brappage with the half bridge with a 4bbl, just less than you would with a 2bbl.

Regarding the ports themselves, here's what I'd do: keep the intake closing timing stock or very mild, cut the bridge in the secondaries if you must, and extend the opening timing of the primaries as far as you can while still supporting the corner seals. I bet you'll get a nice power curve that way. Obviously open up the runners as well.

Definitely spend some quality time with the exhaust ports, too; as has been said, stock 12A exhaust ports suck and high-overlap ports need to breathe. I'd port the closing edge at least out to the stock sleeve, and port them to the side as well. Keep the opening close to stock, maybe with a slight curve. A healthy exhaust port will actually help drivability at the cost of increased noise.