I have three Nikki carbs to choose from to put on my 12a.

1) Jetted for a streetport w/ RB header and exhaust. This was on my engine that had catastrophic failure.

2) Stock. Using this mostly for reference.

3) I'm calling it stripped. It came with the engine I bought. It doesn't have parts on it the the other two do have.

The engine that is going in the car has the stock porting and will have a RB header and exhaust.

I thought I would use the jetted carb, then noticed it had stuff on it, that the carb on the new engine didn't have. I need some guidance. Do I just pick one and go with it or do I need to add or remove parts from a particular carb?

I'm including pics to show the differences.

Thanks!

 

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Best bet is to try them all and see what works best. You can buy Holley 10/32nd air bleeds and use them as fuel jets for further tuning.

 

I've been running a Stripped Nikki on my SP 12A with good results.

 

IMHO, a fresh engine should have a fresh carb/injectors. The stripped Nikki is only partially stripped, more can be removed. I'd pick the best of the bunch and refresh it with a rebuild kit.

 

even the stock port engine can benifit from differnt jetting. there tons of little tricks to do on a nikki. blocking off the ap bleed hole is a good first step. machining the bores in the carb body, lengthening the ap rod arm, adding extras gaskets to the ap for more volume and longer stroke, mechanical secondarys. deleeting the return line and using a dead head regulator set at 2.5 psi exactly! knife edging the extensions that hold the venturis in the carb boars. removing the choke plate. ive probbaly forgot twice the stuff ive mensioned. but a rebuild should be first on your list of things to do or at very least get a new needle and seat.

 

^^ What does deleting the return off the carb and running a deadhead regulator do..? I was under the impression that a return is good to keep the fuel circulating and cooler..??

 

It also helps with pressure build up on the needle/seats.

It's even a good idea to run a return line on any aftermarket carb, you'll see benefits. Regardless of what anyone says..

 

what does blocking off the ap bleed hole do?

 

keeps the pressure steady. and blocking off the ap bleed hole gives you a stronger squirt.