What's the size of the stock carb in mm? I can't seem to find it anywhere.

I have a '73 VW Bug with a two barrel Weber 44mm Carb and because I know the size, I can buy a new carb that is slightly bigger, and I know what kind of power to expect from it.

But I can't do that with my RX7 because I don't know the size of the barrel. Anyone know offhand the size of a stock nikki?

 

Any help would be appreciated.

 

There's a lot more to airflow than just throttle bore. A stock Nikki flows 313 CFM according to Sterling and rx7carl. There's also a lot more involved in carb shopping for rotaries than just "bigger is better" (because it isn't). The three aftermarket carbs I would recommend are: Sterling Nikki, Weber 48 IDA, or Edelbrock 500 Thunder Series. The latter two require an aftermarket intake manifold with modifications for oil injection or premix.

 

Throat diameter Primary 28mm Secondary 34mm
Venturi diameter Primary 20x13x6.5mm Secondary 28x10mm

Hope that helps

 

No love for Holley?

 

Nope.

 

would you reccomend those same carbs for a 13b (gsl-se)?

 

I'd rather go EFI, myself. But as far as carbs, my recommendations are the same as above.

 

Any of the 48mm 2 barrel carbs, DHLA, DCOE, IDA. Depends on what you want out of performance, driveability and porting, if any, done to the engine. Nikki wasn't set up for the SE and there isn't an intake mani made to fit it to the SE engine.

 

I must have the only manifold they made, then.

 

Didn't the REPU have a 13B with a nikki?

I would seriously recommend the Sterling as a replacement

 

^ REPUs had Hitachis. And you can't use a 4-port manifold on a 6-port engine. As far as I know there was never a 6-port 13B intake manifold with a Nikki stud pattern. If there was one, that's news to me. Jeff20B has one that was made with a hacked-up 6-port 12A manifold.

 

Couldn't you just block the 5th and 6th ports to make it work? Or is the Hitachi throttle base a different pattern than the Nikki?

 

I should have been more clear. The Nikki and Hitachi stud patterns are the same, so you can use a Nikki carb on a Hitachi manifold or vice-versa. However, you can't use a 4-port manifold on a 6-port engine (at least, not without modification) because the bolt pattern is incompatible. And even if you managed to do it, it would flow like crap because the secondary runners are entirely the wrong size and shape to match up to the ports. Look at a 6-port engine and a 4-port engine side by side with the intake manifolds off and it becomes obvious why.

Now what you could do, possibly, is use an RB Holley intake manifold with an adapter plate, but I don't know how well that would work.

 

To the top! I have to add a comment about the edelbrock. Thunder series is a good choice, but the performer is also just as good in my book.
I have a stock port 12a with an edelbrock performer 500 and the secondaries open up at around 3800 rpm. So if you want to have adjustable secondaries, spend the extra cash for a thunder series, otherwise for someone on a budget the performer works just fine.

 

Nikki actually did a lot of joint research and development with Hitachi; tight business partners. All the external electricals and pneumatics on the Nikki carb are Hitachi logoed.

Nikki history:

http://www.nikkinet.co.jp/english/co...e/history.html