hogged out vs boost prepped (Nikki)
11-11-15, 08:08 PM
#51
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?
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?
11-11-15, 08:59 PM
#53
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.
Last edited by heynoman; 11-11-15 at 09:02 PM.
11-12-15, 06:06 AM
#54
carb whisperer
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.
11-12-15, 06:09 AM
#55
carb whisperer
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.
11-12-15, 01:50 PM
#56
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
12-18-15, 12:07 AM
#59
Nikki Carb Setup
HeY Jeff - How do I get in touch with regarding purchasing one of your Nikki carbs.
I suppose a Farrel carb will work just as nicely for you as it did for him, but just know he kinda simply hogged his out without really knowing how big to go or what he was doing. I, on the other hand, have done enough of these carbs now that I've gotten most aspects down to a science. The rest is nearly there. Such as how far to bend the accel pump extension pieces. Little things like that. But the big important stuff is all there now. 
Let us know how the carb works out for you!
Hmm, I'm curious. What time frame are you looking at? I tend to get a carb done in a week. Sometimes two weeks if I'm busy.
Let us know how the carb works out for you!
Hmm, I'm curious. What time frame are you looking at? I tend to get a carb done in a week. Sometimes two weeks if I'm busy.
12-20-15, 06:16 PM
#62
12-21-15, 06:22 PM
#65
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.
02-11-17, 07:45 PM
#68
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Updated NA hogged nikki instructions?
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
02-11-17, 10:43 PM
#69
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!
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!
02-12-17, 12:26 AM
#70
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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?
11-10-17, 06:42 PM
#72
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
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
Last edited by SKYDRIFTER350; 11-10-17 at 06:46 PM. Reason: addition
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