82FanTC, it's well documented now that Yaw didn't actually understand air bleed tuning, as can be seen clearly on his spec sheets, and made attempts to throw extra fuel at a problem using known problematic Holley dominator air bleeds as fuel jets, as did Sterling who basically copied everything Yaw did, rather than solve it intelligently. It led to all kinds of cornering problems and the requirement to use the heavy clunky chunky RX-3 floats that displace a ton of fuel and the difficult to get Grose jets (glass ball valves). So, to me, the fact Yaw filled the channel doesn't honestly surprise me.

Ever since the mid to late 1970s, the Nikki was calibrated to run on channeled manifolds once they were introduced at some point on the RX-3 etc. To fill them in and try to recalibrate a modern carb to run properly on it is misguided at best. The flip side of the same coin is to totally hog out the phenolic spacer into an open plenum, and again try to get the Nikki to run properly on it, is also very misguided. I'm like

The carb wants a nice set of channels in the intake manifold and a stock unmolested phenolic spacer. If you have that, then you can get started making big power gains from the carb.

I once tried the dopey open plenum spacer under the carb it was intended to be used with; the Racing Nikki, and it honestly didn't run all that well. Then when I swapped in a normal runner spacer, viola! It ran great!

Oh another issue on some of Yaw's carbs and the Racing Nikki were air bleeds that were WAY TOO BIG!. I'm talking even bigger than factory maximum 90 and 160. I swapped those ruined drilled air bleeds out for a set of factory SA ones and holy cow! Suddenly the carb ran and drove remarkably better!

So I kinda have to wonder. What was the point of all those mods if the carb became handicapped. Was that the point? To lower the power or something? Yaw's carbs and his modding methodology are similar, is all I'm saying.

So be sure to try things. Don't just accept these mods at face value just because they came from a recognized former authority on modded carbs. A lot of those mods were from an era where people didn't share their knowledge freely on forums, and one misguided mod could lead to another on down the line with no checks and balances in place. Heck I'm going to cut a channel on the left side of one of my FB manifolds pretty soon. Why? Because the carb simply runs better with more power! Who wouldn't want that?

 

I look forward to pictures of the carb and modded mani in a cool build thread.

 

max power on e85 is usually achieved 10-15% richer then stoichiometeic AFR . Which is between 12.5 and 13.2 on a AFR meter calibrated for gasoline . I don't expect him to lean out the engine completely to achieve extra power of course that will be dangerous . But being at 12.5 AFR on the high side does leave some room to play around and still be safe. That is keeping in mind that AFR needs to be higher then 14.7 before he technically starts to run lean . Or is this wrong.

 

14.7 is actually far too lean for a performance engine imo. I tried running one lean like that before, all it got me was a cold blooded, hot running, low power and short lived engine. There's a reason the rotary idles at its smoothest around 12.5:1.

 

Forget what people will teach you about AFR and "stoic" because that only really works on paper. They key is knowing how your particular set up works, and what numbers it likes.

 

This is one of the reasons I'm still blowthru I like doing the tuning and not depend on somebody else. , I've tried different tunes on my set up and by experienced I know the motor likes running at low to mid 12 a/f on e85 . But this is an n/a internals 9.4. Turbo set up

 

it's actually not to far off and in his case it's almost spot on. 10% richer then stoich is almost exactly what he is running at 12.5:1 . I agree 14.7:1 does cause the engine to run hot since it is not ideal but its "technically" not running lean .

 

Edit: 15% richer

 

HeY Jeff - How do I get in touch with regarding purchasing one of your Nikki carbs.

 

I don't sell Nikki carbs, if that's what you're asking. Sorry.

 

Bummer, yes that is what I was asking. I have a JDM12a turbo set up, all the external bits, and want to see if there is a way of setting up a Nikki to run with that configuration.

 

yeah,

https://www.rx7club.com/1st-generati...ealed-1083467/

that's how.

 

I don't keep secrets. Everything I've ever done is wide open in the public domain for all to see. Call it open source Nikki something something.

 

Great! Thanks guys, I really appreciate it.

 

That boost prepping Nikki secrets revealed thread needs to be updated. Unfortunately it was put up as a sticky and closed so I can't get back in there. Oh well, it's a good introduction but doesn't go into any details for actual how-to. This thread and some of the others stay updated enough that it's fine as a companion source instead, I suppose.

 

Roger that, I will not take it as gospel. I may end up going with a turbo capable EFI throttle body as an alternative. We'll see, time and money.

 

Would you build my nikki carb for some cash ?

 

Hey Jeff20B is there an updated instruction set for making it just a hogged out Nikki instead of a boost prepped one for us who can't afford a turbo setup? lol

 

Yeah, I have one thing to tack on to this old thread. The only difference is the secondary tune when at WOT:

turbos want 11.5 AFR
NAs want 12.5 AFR

Any richer and you leave some power on the table. Any leaner, with boost at least, you might make more power, but you take a risk.

Everything else is identical. You do all the same mods for NA and boost. Air bleeds, block things off, other mods etc. Everything is the same except for one thing. Yeah one thing! The secondary jet size. That's it!

It doesn't matter what size your venturis are or what size jets it takes to get you to your target AFR. All that matters is the number you see on your wideband. We have this wonderful technology now that the oldschoolers didn't have. Might as well use it. Hopefully you can afford one. Ha!

 

So if I got this right, drill fuel primaries, rejet secondaries, bore venturis, fill secondary long bleeds with solder, and drill AP jet and screw with the 118 bit? Should I modify the jet on the carb top?

 

Great info!

Just need top of shock centre nut torques for front and rear shocks added to list. (The ones you don't touch unless the springs are compressed using a spring compressor)

 

Sorry to bring up such an old one...LOL...
However, does anybody do this type of carburetor re-build service anymore? for others?
to get 'hot tanked' , all re-newed looking & performing great would be awesome!
I am looking for someone that has done this several times & it's no sweat to them.
thank You in advance,

Sam

 

 

thanks!