So, let's discuss performance issues, shall we? I do not know much about these at all, so I would like to see some pros and cons.

I'm currently considering the following for my 12A (while I get the 13B swap prepped for the winter/spring...):

One of Sterlings carbs

The TBI system from www.rotaryshack.com. Go there to check it out. It bolts to a side draft carb manifold, just like any of the side draft carbs they sell.

I'm also considering a good ol' Weber or Dellorto sidedraft.

The Holley set-up is also under consideration.

So, let's kick them around the table, shall we?

 

C'mon, somebody must have an opinion about this.

 

Imagining that the TBI from Rotary shack is similar to what I have just installed, I would have to vote for it,

This set up drives like no other Gen 1 I have driven (and there have been quite a few) The responiveness and smooth delivery of power are remakable. I could not be happier. Power gains are substantial, bout 25% over stock nikki.

Cost of course is of concern as this is by far the most expensive conversion you mention. Ahh, blow the cost.

Oh and did I mention it looks good too.




Regards Sue

 

I'm pretty sure they've all been kicked around the table and then some (maybe all except the "TBI" system).

 

...

 

I have a Yaw carb, which is similar to the Sterling carb. Some of it depends on how carb knowledgeable you are. The Sterling is simple to install and simple to tune. And you get good driveability with it. That is worth a lot to me.

 

I have heard quite a few bad things about Holley's turning ability. I have heard that things tend to slosh around under hard cornering, but I have never seen it first hand.

My Mikuni is pretty kick ***, IMO, but they are all but non-existant nowadays. My main fit with the Mikuni is that it needs tweaking between the seasons. A summer set up isn't perfect for a winter set up and visa versa.

 

EFI is hard to beat. All of the crazy things that can happen with carbs just doesn't happen with EFI or can be tuned out on a laptop. If you got the dime, you really have no choice.

 

so... i dont understand. you want an aftermarket carb for your 12a only to be putting in a 13b this winter? if the car runs now, just leave it as is. if you go with the efi setup you could swap it over to the 13b by changing the manifold, but would have to completely re-tune ofcourse. i like the nikki carb, i'm enjoying the hell out of it every day and have really learned how to tune it. once you get the hang of it, there really isn't an easier carb to mess with on the rotary. the side drafts are beast, but can be such a fuggin pain in the *** to tune. the holley, if prepped correctly, will yield very awesome drivability like the nikki and a good power kick as well. buuuuut, getting it set up right is also a hassle from hell. i have personal experience with all of these. so that's my .02

 

im liking the holley, but yes its a pain in the *** to tune and get working right....... im still working on it

 

Plus the workmanship on Holley's are not very good. They don't do a good job in the manufacture of their carbs.

 

Just my .02, but on our race car, we run a Dellorto. I know that this is a race car, but this carb never has to be touched, once tuned, from summer to winter, from sea level to mountains in NC, runs great. Needle and seat has been replaced by Grosse (?) jet. That made a world of difference. Also, anyone know of grosse jets for a Nikki?

Cheers,
Travis

 

I've done things that make less sense.

But it's slow now. I just bought the Racing Beat street-port exhaust, and want more power.

And that's one thing I'm taking into consideration.... Could the TBI be adapted from one to the other? Can the TBI also handle a turbo if I go that route?

I also have no idea how to tune carbs. Sure, I could learn... Or, I could just be lazy and pay someone else to do it (which is probably the choice I'm going to go with...)

And they look frickin' cool!!!

Yeah, I threw the holley into the discussion just for comparison, but I'm not really interested. Why go with a Holley when I can just go with a Sterling?

 

if you have the $$$ then i would just go with the fuel injected setup. swapping it out to the 13b is as easy as just getting the correct engine manifold and your done. you would just have to re-tune it completely. but that's not that big of a deal. tuning a stand alone is sooooooo much easier than carbs. but you have to make sure you have enough fuel for everything... and more can go wrong. but nonetheless, it can be forcefed as well. you just need the proper plenum/hat. and the proper boost reference equipment for the stand alone you plan on using.

 

One word:

YAW

 

I had a stock 12a GSL, an 84. everything is getting swapped to another chassis right now.
I was running the complete Racing beat street exhaust( the single one).
I have removed all emissions from everywhere!!!
I was on the original stock nikki. then I swapped to a 48mm dellorto, an actuall racing beat one. I didn't really like it so I sold it on Ebay. I am not looking to be a power house with an FB. I like to make them handle thats all. I have an FC, a turboII for my power appetite..LOL
After the Dellorto I put in a nikki with mechanical secondaries. Noticed the throttle response from the mech. secondaries. it was nice, like an on/off switch.
Then I found a 13b carb, you know the old RX5 ones. The carb was crap so I pulled out the jets and put them in my 12a nikki with the advise and help of a buddy. WOW there came some power to the wheels, it was nice....
Then someone told me that if running the 13b jets you can pull out the secondariy chokes and it will rip the *** off a sidedraft carb.....
Keep in mind we are talking about stock 12a motors not ported or anything.
So I tried it.........WOW
Th top end is insane on the car but I find myself driving on it with only using the primaries most of the time. I could only open up the secondaries while over about 3500 RPM or it would fall on its face and bog. I rev the motor to about 8500rpm and it keeps pulling all the way. I would like to rev it higher and see where it blows but not until I have a back up motor. I adjusted the idle air/fuel until the exhaust just barely reeked of raw fuel.....Not to much just barely. For being a stock motor and still pimping out a full interior and A/c it was great. Those 2002+ Honda Civic SI's don't stand a chance. I can take most of the all motor ones around here by about 2+ car lengths by the top of second gear.
I have tried a lot of setups on different FB's that I have owned in the past few years and I don't like spending money on them unless its to improve handling. So I am a self procliamed back yard power researcher......LOL
I always try to make a few more HP with out having to spend money.......haAHHA

 

Yaw doesn't make them anymore. Besides, Sterling/Carl do as good (if not better) of a job modding Nikkis.



But again, for ANY carb, you should learn how to tune it because that's where the last 10-15% of your power comes from. If you don't know how to tune any of these carbs, and don't want to learn, you should buy the carb your local performance guru knows best. Will he be able to figure out what's good for a rotary? I don't know, but it's better than saying "here's a Sterling, tune it" and having him say "a what?"

Jon

 

try and find a dellorto, most flawless carb ever.

 

i love my weber, its a bat out of hell above 4500rpm and doesnt suffer terrible low end loss, runs my gsl in the mid/high 14's and rides smooth

my beef with webers, they untune themselves once a month and the get horrible fuel economy

 

They don't produce Yaws anymore? Makes my car THAT MUCH rarer

 

ok i'm no expert but from what i have read / understood about carbs you can break it down into the options for the rx7:

1: modify your nikki - you can get some great potential, but when it comes to crunch time especcially with large ported engines you will need a better flow rate.

2: upgrade to a different carby:

- dellorto/Weber these 2 carbs are the same, the dellorto has a few small improvements over the weber, the weber has more replacement parts availible but both use the same jets, i also read somewhere that dellorto's can hve the jets changed on the fly which is enormously helpful when doing your tuning.

as for DCOE/IDA upto you pretty much, any differences is in the header design not so much the carby

- Holley: these carbs can get higer flows than the weber/dollertos and have the advantage of having primaries and secondaries but can have fueling issues in hard cornering.

3: TBI this will always be the best but more than doubtfull the most expensive, it will not be limited by flow, only but how much $$$ you are spending on the ecu to run it.

 

A 44mm mikuni can whoop on a 48 Dellorto....
I have seen it several times over the years on several cars, 12a of course.
That's why my Mikuni that is currently on ebay is selling for almost as much as the Dellorto racing beat setup I sold complete with manifold. T^he dellorto setup I sold had a lot of bidders and people watching. The mikuni has way less but it is selling for almost as much...
Supply and demand!!!!!!

 

now my question is the design between a 4bbl and the 2bbl(weber/TBI) for low to midrange rpm. if you go with the weber/tbi you lose the ability to have a two stage intake. does this affect anything?

 

a smaller carb "whooping" on a larger carb that both work on the same principals doesnt make much sense.

 

Actually, I really don't think it should be called TBI because the injector is after the throttleplate on those TBs, but I suppose it is semantics..
A good EFI setup is the way to go. Especially if you are planning on swapping engines. For the value and portability, I would recommend a holley style TB. I think FBII got one recently?