I've done a write up on making the secondaries mechanical on the Nikki. Easy to do, but it creats a dead spot or bog when you stomp on it.
I posted a tid bit about a moddification that I had come up with (cause I thought I was a hot-**** genius...I'll explain in a second) that almost eliminates this problem, and yield excellent results.
Basically it enlarges the volume of the accelerator pump, and then makes the stroke of the shot longer.
You need next to nothing...just some gasket paper, appropriate screws, and a little metal strip.

Anyway, my big head popped when I got a book on how to rebuild Holley carbs where they say to use certain rebuild kits meant for other Holley carbs in order to obtain a different AP diaphragm for a better shot.
Echhh! And I thought I was just so friggin smart!

I can't figure out how to attach the write up here (Cause I'm apparently not that friggin smart!), and these threads won't except such a long page (really long!).
So anyone interested, PM me, and I'll Email ya. Then do me a favor and pass it along.

This worked wonders for me; But then again, I thought I was a genius!
So Northern 7 is giving it a try. I have not gotten any feedback from anyone else, so this is an unproven deal. But the good news is that you do nothing to the carb that hurts/changes it in a way that you can't simply put it back just the way it was.

...And if someone can help me to figure out how, I'll certainly put it up on the board somewhere.

 

...Bumping this up so it gets a bit more "visual time".
(I promise I won't keep doing that.)

 

Well I figured it out. Guess I'm not stupid after all...Just really slow!
Anyway, the attachment got squashed down, and reads like one huge paragraph!
I'm very happy to have been able to post it, but I wish it had kept the original format.

Anyway, read it slowly, and try to figure out where the paragraphs are supposed to end, and new ones start!

And Email me directly, or post right here with any questions, ect. I really need some feedback from those that try this.

 

I said I would'nt "bump this up" again.


I lied.:p

 

Have you no shame.

 

for the info i shall give you the bump

 

Well hey there, Revhed!

...No, I do not have shame! But I do have a concious...and it's telling me that in all fairness I should mention that the first part of this write-up, which pertains to linking the secondaries mechanically, was a beam of light shown to me by none other than the great Revhed himself.

Thanks for the bump, jr(lotza#s)! The more people that try this mod, the faster I find out if it really yeilds good results, or is just a big giant pain the *******. I can't go around telling everyone this is "really great" until others prove it for me.

Wish everyone would get off their lazy asses and go out to the garage and just do this thing! Then maybe I'd get some feedback. I'm riding the great "Ego tide" on my rotary surf-board, but the wave is cresting fast!
Just when the muscles in my neck have gotten used to supporting the weight of my big, fat, overinflated head, it's slowly shrinking!

And hey...If this mod proves to be really great, do I get bumped-up to "Super rotary orgasm inducer...with a beer" status beside the # of posts I've put in?
...That's right; hum like an idling rotary while balancing a beer on her ***...I want to be that good!!!

 

I think I'm gonna try your idea Sterling. I've always had this annoying stumble when I open the throttle at low revs. I've tried adjusting the pump shot and it feels the best with the adjustment at max but the stumble is still there. I'll let you know how it goes.

 

Sterling -

thought I'd better give you an update - the update is there is no update.

I'm rebuilding an old carb and plan to use it for the mech secondary upgrade - the old carb is also serving as a good teaching / learning tool for my better understanding of a carb - I should have some progress to report after Xmas. Great to see you are getting a few responses to your post

have a great holiday

 

Has'nt ANYBODY tried this?!

 

I'd like to do the mech secondary mod, but I don't really have the time and my current project is to rebuild and rejet my carb... If anyone has done it, I'd like some ups and downs about it...

 

As soon as i get this motor in and the car running i will try. Would anyone care to know how to mount an 78-82 oil coller in an 85 and what it would cost. i just got this done. let me tell you this is easy(not) but the lines are expensive. hey just send me an email and i will send the right up to you. email is jr69187@hotmail.com

hey sterling send me some mail as you get this all worked out with the supercharger.

 

Hey Sterling, I never bothered 'cause when you remove the spring entirely, the secondaries WILL open as far as the primary throttle linkage allows, so that it's just like mechanical linkage. And no bog on my old setup either so I didn't have to touch the accelerator circuit

But I'm always thinking of new ideas and I came up with one that requires the vacuum diaphragm be plugged off, so mechanical secondaries is an absolute must. I'll let ya know if the project ever gets off the ground.

 

...nothing is prompting them to open up. Are you counting on air flow to open them for you? How can you be sure they are opening all the way?

 

bringing this post back from the dead here..

I did this alteration just as he said, I love the modification and have had no problems with it whatsoever at all, It's kind of like taking and automatic transmission and making it manual in terms of how it feels, I now have precise control over when I want those secondarys to pop open and get that lovely rush of power, if you do this modification I do recomend that you purchase a rebuild kit and only really for the AP diaphram, I thought the one that I had was in perfect condition but when I saw how the new one was designed I thought again, even if your stock AP diaphram is in perfect condition the new one from the rebuild kit has 2-3 times more travel from the better design. For the extension on the AP lever I used a still metal ruler, I just ground it down to about 1.5" and drilled holes roughly 1-1/16" apart, then I took it in a vice and put about a 45* bend about quarter way between the 2 holes. making the AP gaskets was a little tricky because the screw holes seem to be so close to the diaphram travel area, oh and I just put the gasket that i was making on top the the outside AP housing and pressed a quarter in it to make an outline to cut, worked great. I bought the longer screws for the AP from nappa for 12 cents each. I say that if you dont have much money this is a great mod to do! I'm 18 and it took me about 4 hours to completely tear down the carb and piece it together and mod it. Thanks Sterling for all of the info and insight to these seemingly small changes that make such a huge difference. On a side note I cannot feel any flat spots, on occasion one blurp for a split second but it's nothing that bugs me at all.

I own a 1980 rex btw, have full RB exhaust and a mutilated stock air cleaner with lots-o-holes in it (it's the small things that are free that get you the most satisfaction)

 

were is the write up please help wtf

 

Hey, necro my friend. This thread is dead.

 

10 years!

damn.

 

Well...we know the search feature works at least...lol

 

**** man, this is WAY more simple than the OP is making it. Take the shaft and wire the secondaries to open after the primaries...

When I was farting with my 12A I did it with a zip tie. It worked fine but other things pushed me into rebuilding my 13B. I haven't made a more permanate solution to the zip tie, but it is working fine.

Other than removing the acc pump (I only did it cause I was too lazy to transfer the exiting working pump from my other nikki). I had no flat spots.

 

Secondaries WOT





Zip tie.





I did this out of pure haste and wantting to GO. I didn't trust that vacume system. Still don't.


EDIT: Yeah, I should mention I REALLY hate vacume lines... If you notice all of them are gone. I riged up a wire choke. The only vacume line goes to the spark advancer. (I don't know why Mazda choose a vacume advancer... they coulda done it the same as motorcycles and had it run off of springs MUCH better IMPO)

 

ive done the ziptie thing to mine.. and it works great. but now i have this stumble when i get off the gas. or right as i step on it. kind of strange... dont know if its related. but ehh. will this mod help that?

 

i will allow this thread to remain open, as Sterling provided excellent advice during his stay with us. no bashing or nasty comments about Sterling or the post will be deleted. i'll leave this open for research and questioning about the mechanical secondaries.

 

What else have you done to the car intake exhaust wise?

You might wanna think about larger jets or a bigger acc pump jet.



I meant no bashing or ill will to the OP. Just saying a pic's worth a thousand words.

 

Amazing to be resurrected after 10 years.

Still contemplating this mod or not, I'd like someone to post up their MPG reduction and overall advancement in throttle response after completion and a few months of driving.