85rotarypower

I beleive all carbs use a velocity stack. You just can't see it as easily as the webber.

One question to the experts, If the Nikki really is fussy with tuning, why would Mazda use it and not a more reliable carb?

fitzwarryne

Originally Nikki carbs were seen as a good compromise between perforn\mance as measured in 1980 and economy and pollution control. The Nikki was a well designed carb for stock ouput and was very reliable, in stock form it could easily handle bolt-on modifications. Webers on the other hand came in as a pure topend performance carb with nothing special lowdown, thus became the carb of choice for racers. The could be easily fine tuned by experts for special events.

Holley and a few others of historical note came somewhere between them in characteristic depending how they were set-up. For a 1990s era carb they had their good points

Twenty years of experence has widered the carb set-up range. Now Webers are more streetable, particularily with the 48IDA but still need a streetport to do them justice.

The Nikki carb has gone a transformation with tuners making modifications to its specifications. The ultimate versions are up there in power with the Weber, the only loss is emission legality. Thus, you can now choose what you want out of a Nikki without being up for megabucks. To me $1000 for a carb to go on a $3000 car is an unusual decision!

The evidence is that until you get serious and go bridgeport a Nikki is the best cost choice unless you want the enginebay to look ricer.

Sterling

Define "fussy"...
The Webers and the like are two barrel carbs. The signal that draws fuel out of the main circuit is very strong.
With a four barrel the signal is divided in the high end between all the bores, so the main circuits see less signal. That is'nt a problem, as everything is jetted for it (IE, you're not going to lean out at the top end as a result). But it makes the modded Nikki more subject to changes with "track conditions" than the two barrel carbs because temperature and elevation changes will effect it more.
These changes still effect the two barrel carbs, but it's easier to realize the effects with a four barrel.
In effect, the moddified Nikki is going to be more sensitive.

To get the most out of a modded Nikki, you would have to change jetting with drastic changes in temperature or elevation. "Most" is subjective, too. Don't get the wrong idea that the carb will be a dawg every time the temperature drops ten degrees. We're talking seconds on the mile here.

813KR$

Remydrm: I have a non-Rotary Holley 600 and the top end is what I have to concentrate on! I had a SP 13b with a stock Nikki and That IS what had the Screaming Top End ! ! ! In my opinion the Holley's need to be tuned for the top end? I could be wrong but my *** dyno tells me Nikki's run! With the Holley I am currently running my best 1/8th mile time is 9.5 seconds, which Iam not happy with.

I would like to get a Holley to Nikki adapter and buy a Sterling Nikki and see if I can dip into the 8's, while using the S type Nikki sitting on top of my RB intake!

Webers use velocity stacks to increase the air speed in the big 2 barrels, Holleys dont because it has 4 barrels which are individualy smaller in diameter, which increase velocity. I wish I could find some velocity stacks for my Holley, I think it would make a difference since people say the 600's are a little big for the 12a. Big carb means less velocity. Velocity stacks should theoretically increase the volocity in the 600 but still supply plenty of A/F.