Project Fat Nikki
 

I've procured an 85 nikki and intake manifold from pullapart for some fun.
My goal is to hog out this nikki to the best of my abilities so that it can be used in
place of my current Dellorto setup. I have no compelling reason to do this, the
Dell works great. I just thought it would be fun to do. It will initially go on my
stock port 12A.

I'm cleaning and disassembling right now and will get pictures up as I go along
making the various mods. I know I could get a sterling (maybe) or from SR
Motorsports but I want to do it myself.

So I'll post my detailed plan for the modifications to be done. Please feel free
to post up anything I may be missing or can do better or have first hand
knowledge about that can help me out. In return I promise to deliver lots
of details and pictures as I go along.

Heres the plan. I've numbered each step uniquely and grouped then logically
by component to make discussions easier. If nothing else I hope this helps
anyone else contemplating hogging out their nikki.

AIR HORN mods

done A1. remove choke plates and rod and seal up holes

done A2. remove choke diaphram and brackets, plug holes

done A3. dead head fuel inlet for now. Just cap with bolt and gasket. Keep return and other gasket just in case.

kept A4. remove air vent solenoid, plug with bolt
But disconnected

done A4. remove alt. compensator, plug holes

MAIN BODY mods

done M1. remove dashpot and bracket, plug holes

done M2. remove secondary diaphram, plug holes

done M3. remove TPS

done M4. Drill out AP jet, top center and top 2 holes to .5mm

skipped M5. Drill out AP nozzle to 0.050 "

done M6. Double up gaskets on AP diaphram

done M7. Add extension to AP pump arm.

done M8. Pull primary and secondary booster venturis and cut extra arm off and smooth remainng arm
also polish up inside each venturi to clean up and smooth it out.

done M9. Mill down primary and secondary venturis a little bit

done M10. Drill out fuel and air jets. Or buy holley air bleeds for fuel and only drill air jets.
- only drilled the primary fuel about 1mm or so.

THROTTLE BODY mods.

done T1. Hook up mech secondaries

done T2. strip down linkages to bare minimum

done T3. cut half of secondary shaft away, use shorter small cap hex bolts to attach butterflys

skipped T4. use small cap hex bolts to attach primary butterflys.

INTAKE MANIFOLD mods

done I1. remove butterfly and rod, fill holes

done I2. cut channel between rear primary and seconday opening

I3. install ACV blockoff plate

I4. cut or plug pipe off of the back of the intake

done I5. plug or cutoff extension off rear of intake
Plugged with JBWeld

Let me know if you run into any road blocks. I can also do the machining of the venturi's for you if you can't get the proper equipment yourself. Keep us posted!

Thanks for the offer. I'll keep it in mind.

I'm amazed at how many small tweaks that are needed to do this. Anyone
modding nikkis like yourself and sterling are really earning your money.

Its a lot of small details, thats why I split it up into the 4 major areas. I'm
going to do each set before moving onto the next.

Yep! DETAILS DETAILS DETAILS! Especially polishing the booster venturi's. Takes me hours to do them. Anyway if you get hung up or just want to bounce ideas hit me up. 954-288-4508. Keep us posted with pictures.

T G FARRELL from the last thread it looks like you'r on the right track now.Lots of guys modify the stock carb with great results good luck

No real progress to report. I chem dipped the major pieces but I need to get
some carb cleaner and go at it with a brush and elbow grease this weekend.
I don't have a parts washer so I have to do it the old fashion way. I'm not in
a hurry so that ok.

I'll be ordering the GP Sorensen carb kit as well when I pick up the carb cleaner.
Once its all clean I'll take before shots of everything and then start modding
the carb from the top down.

Well the carb cleaner I had sucked. It was from advancezone etc and it was
so safe you could water your plants with it. I did some research on the net
and I found that what I wanted was lacquer thinner. It has all the best
ingredients like toluene, acetone, etc.

So I soaked the carb and intake in this yesterday while I was doing some yard
work and they cleaned up pretty good with no real scrubbing. I still want to
take a brass wheel to it all for final clean up, plus I'll reuse the thinner when I
pull the jets as well. No pics yet. I'll post them after I wire brush it all and
before I pull off any jets or venturis.

Got the rebuild kit in and it looks complete. Now I just have to drop by HF
tp pick up some indexed drills and a few other odds and ends for my dremel
supplies.

Not a job for those looking for quick rewards. :) I admire your patience, and look forward to seeing your mod work...




.

Shhh. Just don't tell Ray about it.

Update for pics
 

Heres some pics of the carb partially dissassembled and after hitting it with some lacquer
thinner to clean it up. I haven't done any other cleaning yet. I plan on using a home
made soda blaster with my compressor to do the final cleanup. That will be a lot of
fun! This carb was really easy to pull apart. Can't tell if its ever been opened before
but it seems pretty unmolested. I'd call it a good buy from pull-a-part so far.

So heres the pictures, top and bottom view of each component from the top of
the carb down to the intake manifold.

Already remove the choke assembly and few other bits.
https://lh3.googleusercontent.com/-j...0/SAM_0346.JPG

https://lh5.googleusercontent.com/-9...0/SAM_0347.JPG

https://lh5.googleusercontent.com/-W...0/SAM_0344.JPG

https://lh6.googleusercontent.com/-H...0/SAM_0345.JPG

https://lh4.googleusercontent.com/-V...0/SAM_0348.JPG

https://lh3.googleusercontent.com/-n...0/SAM_0349.JPG

https://lh4.googleusercontent.com/-p...0/SAM_0353.JPG

https://lh4.googleusercontent.com/-3...0/SAM_0356.JPG

Tim I can't believe Ray got to you. Ray will never find this thread over here. You'll have to show it off at an OGTA when your through.

Thats the idea Holly :rofl: I plan on unvieling it at some event where Ray and
I meet up. I won't have it done for the March OGTA, so maybe for DGRR or Mitty.

Actually, I want to do this so I have 2 carb setups to play with when I build
another motor. I figure I can keep the Dell which is already tuned to a stock
port 12A very well on the side and put this fat nikki on and tune it as well.
That way when I build a new motor I have lots of options for getting it tuned
and ready to roll. Also the nikki was cheap and its very cheap to do the work,
you knows us old guys, we like cheap.

The new engine will be some sort of ported 12A, haven't decided
details yet, just have a couple parts engines sitting in the garage apart at the
moment. Heres my thread on that.

Update
 

I channeled the intake manifold and just have to plug up a hole where the
rod for the butterfly come through. I also clean up the intake a bit but I want
to media blast it before final assemply. I may clear coat it to keep it nice looking.

https://lh3.googleusercontent.com/-Z...0/SAM_0420.JPG

Did some work on the throttle cable bracket and removed some things to simplify
it a lot. No pic of that yet.

Worked on the throttle body but had a hard time getting the secondary butterfly
screws out. I tried heat and that didn't help, so I'm soaking in PB blaster and
will give it a go later this week. Any tips on removing those screws would be
great. Hate to have to drill em out.

Also worked on the carb body some. I trimmed the arms off of the primary and
secondary venturis and polished them a bit. Also ground down and polished
the chokes as well. Didn't ream them too much but I may do some more later.
I haven't shortened the oil inject tubes but I did pull them out a bit as they
were almost right up against the small center venturis in the primaries.

https://lh5.googleusercontent.com/-d...0/SAM_0425.JPG

Keep up the good work guys..

The Stock nikki s a great carburetor and we need more folks with solid know-how on these carbs for street, race and blow-through projects.

For the butterfly screws:

#1. Use a screw driver that is the right size.
#2. Place the screw driver on the screw and give the screw driver a good tap with a hammer. This not only sets it in the screw head but also give the threads a little shock to knock them loose. You may have to repeat this a few times, but I've had 100% success with this.

I automatically do this for all the carb screws just to make sure I don't strip any, works like a charm.

Good tip, I'll give it a whack tonight :lol:

Lmao, gotta love puns. Just be careful to secure the butterfly closed. Otherwise your screwed! :smilielol5:

That worked great, I got all the screws loosened up. The modifications continue ...

Awesome! Keep us updated. :cheers2:

Update
 

Got the throttle body 90% done. Cut the secondary shaft in half,
hooked up the mechanical secondaries, and simplified the throttle linkage.

I may do more on the throttle linkage once I have the rest of the carb stacked up.
I want to try and not have to use the existing return spring and teeter totter so
the top is easier to get off (ala Sterling).

I also still have to fully adjust the mech. sec. too. They're close but it will have to
go on the car to get it just right.

I also updated the first post as I've complete tasks if anyone wants to follow along.

Top view of fully opened butterflys using mech. sec. linked up.
https://lh6.googleusercontent.com/-k...0/SAM_0427.JPG

Overview of throttle body with simplified linkages and mech. sec. setup.
https://lh4.googleusercontent.com/-k...0/SAM_0428.JPG

Close up of simplified linkage.
https://lh6.googleusercontent.com/-j...0/SAM_0430.JPG

A buddy of mine has graciously volunteered an ACV block off plate. I sure do
appreciate it Mike, if your reading this.

I hope to have this on for DGRR but the goal is to have it ready for the Mitty.

I make a one piece aluminum spacer for the primary throttle linkage after I remove all that extra stuff. If you want, PM me your address and I'll send you one.

Thanks for the offer Rich. I'm fine with the existing stuff I have for now.

I just hope after I finish this project that folks understand how much work and
detail goes into one of these. My hats off to anyone that does this as a service
for others. Whatever your charging, its not enough :lol:

Drilled the primary fuel jets, AP jet and milled the primary venturis down a bit
more as well as the secondaries. Also cut down the length of the tubes for the
oil injection. Updated the status of these items on the first post.

Put the carb body into soak in cleaner last night. Next up is the homemade
soda blaster to really make it all clean.

http://www.aircooledtech.com/tools-o.../soda_blaster/

I need to plug some holes on the intake and carb. I was going to use JBWeld
but was concerned about gasoline interactions. It definitley has issues with
E85 gas from what I've read. I think I'll just tap and plug with some set plugs.

Scrap that, I'm just going to go get some JBweld and use it. If it has issues in
the future I'll deal with it. I want to get this thing together and on the car
this weekend and see how well it works.

Things left to do:

1. JBWeld some holes up.

2. Modify the AP lever and make gaskets.

3. Soda blast for final cleanup.

4. Add the fast idle linkage back in.

4. Assemble with rebuild kit.

I soda blasted the intake, throttle body, main body, air horn assembly and the
base plate. Looks really good. Soda blasting really works well on this stuff, got
most of the old scale off and cleaned up real good. I'll post pics on Saturday when
I reassemble the carb.

Looks like I'll have it all together this weekend. Won't be putting it on until
after DGRR but it should be on and tuned for the Mitty.

Clean up pic
 

Heres some pics of the intake, main body and air horn after cleaning it up
using the homemade soda blaster.

https://lh3.googleusercontent.com/-6...0/SAM_0444.JPG

And these are all the small parts cleaned and ready for assembly.

https://lh6.googleusercontent.com/-u...0/SAM_0445.JPG

Completed carb pic
 

Got the carb all back together. Redid the throttle linkage to put the fast idle
linkage in. Also add the extra gaskets to the AP diaphram and extended the
AP lever arm. Bench adjusted everything as well.

Heres the front view (drivers side) of the assembled carb.
https://lh5.googleusercontent.com/-w...0/SAM_0449.JPG

Some detail on the linkage. Pics like this helped me when I was trying to get
this setup correcly.
https://lh3.googleusercontent.com/-G...0/SAM_0454.JPG

A top view showing the steamlined booster venturis and all.
https://lh3.googleusercontent.com/-c...0/SAM_0458.JPG

A buddy is shipping me an ACV block off plate. So this won't be going to DGRR.

Sunday when I get back from DGRR I'll toss it on and see how it does. I expect
to show it off at the Mitty the following weekend.

I updated the first post with what has been completed. All thats left is the ACV
plate and then plugging random vacuum hose fittings on the throttle body and
intake manifold.

I haven't decided what to use for the air cleaner. I have the blue mazda one
that came on the carb but it has lots of pipes on the bottom for useless
emissions crap. I guess I could just cut em off and seal em up. I'd eventaully
like to get a cold air intake setup ala ReSpeeds radiator support. Thats another
project and another day.

My wife and neighbor think I'm crazy but they just don't understand how much
"fun" this can be.

ACV plate arrived ahead of schedule (Big thank you Mike, I owe you many beers
at the Mitty or next OGTA).

I wish I had time to put the carb on and tune before DGRR. Oh well. Sunday it is then.

I put the nikki on tonight. It runs but has a high idle 1500 or so. Other than
that it seems to work pretty well. I will have to test drive it tomorrow.

The high idle may be due to the primary fuel jets being drilled out but I
didn't touch the primary air jets on top. That may make it overly rich at
idle. The idle fuel adjust seemed to have very little affect. When I looked
down the primaries during idle I can see fuel dripping fairly constantly in
both barrels but it doesn't look very well atomized. Could be just the low
air flow or is it a symptom of not drilling those primary air jets to match.

I also need to hook up the FBVS as that may be causing me some headaches
as well.

I don't think I have any vacuum leaks. I put a vacuum guage on the second
nipple from the front of the carb base gasket and it read a steady 10 and when
I blipped the throttle shot up to 15 or 20 and steadily returned to 10 as it
settled back to idling (at 1500 rpm). I expect if I could get it to idle at 750 rpm
that initial vacuum signal would be zero since thats the one for the advance on
the dizzy ( to my understanding anyway).

Of course I want to take this down to the Mitty this weekend and my wife
thinks I'm crazy. Maybe I am but its fun :D

I hooked up the FBSV and drilled the primary air bleeds to match the fuel jets.
No big difference. Also realized I forgot to plug the banjo bolt hole on the intake
manifold. Can you say vacuum leak. Plugged it with a bolt. Still has a high idle.

Took it for a test drive and it pulls pretty well and smacks you when you hit
the secondaries big time. Those need adjusted to come on a bit earlier but
thats minor. Won't hold idle and easily floods. Pretty sure its a vacuum leak
probably around the throttle body and/or spacer.

Definitely not taking the car with this carb to the Mitty. I may just swap the
Dell back on and go with that and come back to this at some later date.

Check for a vac leak where the primary throttle shaft slides into the throttle body on the linkage side of the carb. My sterling had a nasty leak there. There is a write up of mine stickied on 7club on how to fix that with an o-ring if you find a leak there.

I had the same problems with my carb when I got it. High idle, would stall when coming to a stop, under 1,800 RPM it would buck bad. Had to really know how to drive it to make it work right. I was at DGRR with the carb un-working lol For some reason too, my A/F screw has to be WAY WAY out but shes idling good now at about ~800RPM with 15in/vac at idle. Before it would do exactly what yours is doing, little to no vac under 1500RPM, but I used the third nipple from the left on the carb spacer.

Yeah I was going to check with some propane around the shafts. I remember
when I pulled the primary shaft out to cut it up it had some gooey stuff on the
shaft. I may try pushing some grease into it from both sides and see how that
works.

I won't get back to this until June, too much other stuff around the house to
deal with at the moment.

Oh well, a year later or more and I'm playing with this again. Put it on yesterday after
going through it again. I smoothed down the spacer gaskets on both sides and I think it
wasn't sealing well and causing vacuum leakage. I was able to get it to idle down around
1100 or so but it wasn't always stable. I wish I could remove the old gaskets on the spacer
and use the new ones that come in the rebuild kit, but those things seem to be glued on
and the space is plastic, so no bueno.

My float bowls are sticking and after shutoff and restart a lot of times it just pours gas
down the intake until I get them to settle down. So I need to pull the top and doctor
the float needles a bit or reuse the old needles and seats which I kept. When the floats
are working the level is on both bowls, so floats are adjusted good.

Also, I have the fuel inlet dead headed into the carb. I'm going to run the lines for the
return and hook up the return line and see if that helps. I think with the inlet dead headed
it is bouncing the float needles and sometimes sticking causing issues as well. Anyway,
it was a lot of fun playing with it. Had to stop when the engine started to overheat
cause I turned off my electric fans as I was trying to conserve battery. DOH!

I will say its very smooth on accel compared to a big 2 barrel like my Dell. I should be able
to just smash the go pedal without thinking once I get it idling good.

What kind of fuel pressure are you running? I've heard the Nikki likes a lot lower fuel pressure than most carburetors at 2 - 3 psi. Definitely following your progress. :biggthumpup:

I'm running the same I had for the Dell, 2.5 psi or so. I really think the new needles are the
biggest issue. I've heard others had problems with them as well.

Added the return to the carb and ran a return line to the tank. Also pulled the top and
massaged the new needle valves to fix the sticking. Noticed the new needles have a much stiffer
internal spring that the old ones. Anyway, turned the key the first time and my bowls
runneth over. Tap tap on the top fixed it for now. I may go back to the original valve or
needles anyway to see if that fixes it.

Also when adjusting the floats it seemed like they would settle differently every time I
measured them when the top was upside down. The drop was always consistent. I think
I'm seeing the needles bind. I'll try the old needles next if it continues to flood. Don't
trust the new ones much now.

Put the old needles and seats with the mesh filters attached. Put the top back on the carb
and the first time it ran over as before. I then started it up and looked at the float levels.
Front was 3/4 and the rear was like 5/8. Adjusted the floats until the meniscus of the gas
level was at the half way mark on both bowls. Then I proceeded to adjust the idle and the
air mix. The air mix has very little impact and I could only get the idle to be stable at
around 1100 - 1200 rpm.

I can tell its running rich by the smell and the temp. So I think my main jets are drilled
out too far. Not surprised by this so I'll have to drop something in there the right size.

Didn't take it out for a test run yet and it still sometimes drops through the idle and
wants to die after coming off of a sudden throttle input.

Tomorrow I'll see if it still wants to run over after sitting when the pump runs. Thats
annoying at best.

Turned the key this am to start the fuel pump and it still ran over. Something is sticking
after sitting a long time. The float levels before I did this were fine. So the floats should
have been closed anyway. Unless they are filling or absorbing gas somehow. They are old
but look ok except for some bubbling on the surface (no breaks).

I also now think my idle circuit is basically not working, perhaps due to air issues caused by
my changes. Its a puzzle right now.

I may have to get another carb and start swapping things like jets and tubes in and out
one at a time to see what happens.