85' Stripped Corner Carver
 

In the process of tweaking and modding an 85' with a 12a in it. I've been posting in a regular thread and figured I may as well make a build log of it.

Link to the image album

^ Pics of the car ^

Probably going to tear the bolt in cage out and put a weld in. I think it is out of spec anyways. Same with the harness and seat, both go out of spec in 2013. I have a new Corbeau seat and a new 5-point harness (for about 1 year now) and I am going to be using that. The Corbeau seat is currently on a racing sim I built with panoramic display.

The guy who owned it before me was going to run it in a Spec-7 class and thusly some mods that have been done are:

• Chopped Strut Towers
• Tokico blues
• Lightweight Rims (ugly as all hell but light)
• Racing Beat Header with open exhaust
• Stripped Nikki (internals not modded, vaccum secondaries)
• Oil Pump delete (runs Idemitsu premix)
• Oil Baffle Plate
• Electronic Radiator Fan
• Fuel Pump upgrade
• Sway Bars (TMC - CSM-4018 w/ TMC end-links)
• Front Suspension Bushings from Mazda Comp for control arm, tension rod and idler arm

That's the big things, everything else that is modded is just stuff that was stripped (interior dash and a/c etc.) or mods to the exterior. The heater core and blower were still inside but I ripped that junk out. I am not running this in Spec-7 class but rather time based classes.

I have a buttload of spare parts:

Rear Bumper
Set of front fenders
Rear Hatch glass w/ shocks
Mikuni PHH44 2-barrel Carb (I cleaned this biatch up and got it running, first carb I ever worked on. Sounds AMAZING at high rpms but is an absolute terror to drive sub 4k rpms. It loves to bog and kill if you so much as look at the pedal too heavily.
2 spare Nikki Carbs (not including the one working one on the car)
Rear housing bearings or something like that
Roller Bearings
Hawk brake pads
Case of Idemitsu premix
Spare rear end
Spare rear lower control arms
5 sets of tires
2 sets of race rims
1 set of stock looking rims with rain tires (has "mazda" on the rim)
Spare passenger side door
Spare Hood

That's just the stuff off the top of my head. There is a whole box of small parts that I am not even going to begin inventorying until I need something to replace.

So right now the car runs. It doesn't like to idle while until it's totally warm and even then if you let it idle too (minute or so) it will kill. I've messed with the idle mixture on the nikki but I am no expert and don't really know what to look for.

In the interim I have broken down one of the spare nikki carbs and ripped out the internals (jets and venturis and butterfly linkage) I am in the process of cleaning up the jets. The edges are pretty jagged so I am EXTREMELY lightly filing them sharp.

My plan for the venturis is to rig them up in a 555 bender I have and put it on slow then rig up a table in front of it that I can rest my dremel on to get a consistent grind angle. Theses are all spare parts and I have a whole second set of spares in the other nikki if I mess up so no harm no foul.

I am going to mod the butterfly linkage to allow for more flow as per the guides on this forums.

Here is what I am doing right now as I write this up:

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Filed one in the back, untouched in the front.

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Rebuilding carbs are fun. Very time consuming. But yhere is many people here that can help along the way. Sounds like you have solid build platform. Will it be a race only car?

Race only.

Step 1 - GOOD LIGHTING

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Step 2 - Get to work

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What I have completed so far as of tonight:

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Managed to find the brass on one of the secondary jets. Broke open the second spare and busted out a fresh one so no harm no foul I guess. Least I learned something in the process.

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Nice work :icon_tup: Be careful with those throttle shafts though, I think those are the thinnest I've ever seen! They're known to twist and could even snap, sending pieces into your motor.

The pic may be a little misleading, they are pretty thin, but the edges also taper off so it may look thinner than it is. I'll put a caliper on it and measure it tomorrow.

The throttle shafts are .050" at their thinnest. I can't twist them by hand unless I really f'n tried.

I am enjoying working on the nikki, I may break out the Mikuni PH44 next and get it tuned up. I love the way that thing sounds and performs at high rpm.

You'll probably be fine then. Easiest test is to put everything together, open the throttle all the way, and see if the plates are open evenly. These things are fun to put together. There's so much crap you can remove from them and they'll still work great.

you might want to build a simple throttle stop, fixes the twisting shaft "problem"

I'll have to look into this.

I am still trying to determine if my throttle linkage is correct for vaccum secondaries, or if I should just mod to mech secondaries and forget trying to figure it out. It may be set up correctly, I just want to make sure before I tackle other issues.

Having a CnC shop has it's benefits. I may not have a mill or a lathe but I've got a 535 pipe threader and a dremel.

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I need to dunk them in some parts cleaner to get all the gunk off and get them totally clean but they don't need any more grinding.

Is there anything I should do while I have the carb off? I am thinking of getting some freeze plugs and modding the irons so I can swap when needed without adding more coolant. I still have the manifold on right now but it's no big to take it off and mod it.

Maybe check for compression or something? I dunno... I am new to rotaries and I want to go over every inch of this car to make sure it's running properly. I don't know what to expect and how it should run with the mods it has on it (not the mods I am doing to the carb parts) so I will need some guidance (as in, should I be expecting a lumpy idle or being extremely cold natured etc.). I don't want to be troubleshooting a problem that isn't a problem, know what I mean?

impressive work so far. I really don't get tired of seeing work like this. you definitely have my attention.

Beautiful!

Broke open the working carb to put the new internals inside and check out the inside of the rest of it. One gasket has a small tear in it but I think I can still use it. What do you guys think?

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One of the jets was completely blocked off.

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So do I swap in the jets from the donor carb and just roll with it? They are larger. 70/140 are the stock jets and 90/160 are the donor jets.

And can I grind off the brass tubes sticking out over the venturis as seen here?

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The other ends have vacuum caps on them.


Also, does anyone know where I can get a good gasket kit? If I can get some new gaskets I will just go ahead and replace them.

Looks like progress!

I'd use the bigger jets, you should flow more air now. If it's too much, go back to smaller.

I wouldn't cut the oil tubes down. Seems to me the oil would then be clinging to venturies rather than zooming into the motor where you want it. If you're premixing you could remove them altogether and fill with quick steel.

The Sorensen kits I've used twice lately with fine results. If you only need gaskets, an exacto knife and gasket material would be cheaper.

I run premix, hence them being blocked of on the other end so I will chop them to remove the obstruction. I'll try using the bigger jets and see what happens I guess. That and I have some gasket material laying around so I will just cut a new one since I just need the one it seems.

I need to also figure out the thread size of the screws used to connect the butterflys to the throttle shaft so I can replace them with alan head screws or maybe torx.

Went to re-install everything and I realized the venturis are numbered and I dont know the orientation on how to install.

Lookin for some help here. I searched the forum but couldn't find anything on this specifically.

My neighborhood Ace hardware has been able to provide nearly every screw, nut, and bolt I've needed. Try Em out.

Keep at it, I'll be interested to see how the new carb works for you.

I looked at it for a while, realized they can only go in one way really. Also confirmed using the second spare carb.

The float needles are VERY dirty on the end. Do I need to replace these or can I just scuff them clean... Or should I just leave them alone?

I am ready to put it all back together (all except the throttle body, that is soaking in carb cleaner). Pics incoming later tonight.

Forget the pics... Had taken a crap load of pics of the throttle linkage before I tore it down and of course I had to delete them all before I went to put it back together. F my life.

Need guidance on how to rig back up a stripped nikki with vaccum secondaries.

Managed to work it out from the other two spares.

Too tired to explain pics, it's 4:30 AM and I am beat.

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From here on my porch it looks good. Sleep well.

It runs. Still has a bit of a lumpy idle. It used to kill after idling for too long but now it can idle all day at 850-900.

New guy just moved into the neighborhood and he races a mazda speed. He has a buddy who has 3 FC's and knows a lot about rotaries. Hopefully I can get him to take a look at mine.

After looking it all work and move I realized I still had some problems.

1. I hadn't put on the primary throttle stop.

2. I realized this before I put it all back together (while I was modding the shafts). The donor primary shaft is shorter so I had to remove a few things from the throttle stop side. It also isn't thread and has a screw cap end whereas the original was threaded.

3. Some of the secondary linkage was catching on itself (the part that is linked to the primary) and was therefore forcing the primaries open sometimes (when it caught). I broke it down and straightened everything out so it doesn't do that anymore.

Video below.

Getting freeze plugs and pins tomorrow for the carb linkage.

LINK TO VIDEO

Do yourself a favor and throw that Nikki in the nearest garbage can and buy yourself a nice Weber 48 Ida carb.

Why is that? You want me to buy $560 carb for an engine that's near obsolete?

I've got a Mikuni PH44 if anything.

I fixed the linkage and got everything back together. I need help identifying what this port is in the pic below. It's not blocked off or connected to anything.

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There's also this solid line coming from the car that doesn't go to anything I just blocked it off originally but I'd like to know what it is.

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There's a bit of flex on the butterflys when I try to twist it past the throttle stop. Guess I just need to be light on the pedal at WOT.

I think that port needs to be connected to something, I just don't know what.

Re-reading the carb stripping tutorial, at the end the carb looked like this:

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Both fuel inputs are hooked to something (though one may be blocked off, I don't know... The smaller one on my carb goes to nothing) and the port I am trying to figure out goes to something as well.

Also, the air vent solenoid isn't powered and is still in the carb, do I need to supply it with 12v source?

I also need to figure out what these two things are on the dist. They aren't capped.

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The throttle pedal looks to have a bolt stop so I can just adjust that so I don't twist the throttle shafts at all.

Ok... so those are the vacuum pots to advance the dizzy, right? Now how do I determine if they need to be hooked up or not?

And another discovery... The line that is blocked is the fuel return line. Not sure if I need to use it or not yet.

I have a Holley Red fuel pump upgrade and a Holley regulator. I have no idea if it is bypass style or not because the numbers on the regulator don't match anything I can identify from Holley so I guess the return line will stay blocked for now.

The number on it is 264 5-2.

Do not cap the vacuum advance lines, you either hook them up or leave them open

Could you explain what leaving them open does vs. hooking them up? I'm not sure if I should or not.

I think that open port pictured above needs to stay open. In pics seen in the carb stripping manual it appears to be hooked to the rats nest. I dont have a rats nest.

First you need your return line hooked up. Second put a cap on that port. Third make a cover plate for your altitude. Compensator (the triangle area next to the passenger fender with all the holes), what ever number this one is take a piece of hose from the spliter on your advance and hook it onto the second hole from the left on the carb spacer. Also the jet that is plugged up replace it. That should get you started.

Jet has been replaced. I actually put the carb back on the car and started it yesterday. It ran a bit better than before (I am guessing due to the jet).

I was thinking about hooking the vac advance back up as it seems to help on gas and not be that much of a drag on power for most people (just based on reactions from people on the forums).

I am going to remove the ACOMP, I just haven't had a sec to take measurements to make a plate (gonna waterjet it). The pic above was taken out a guide I saw on the forums. My carb still has the ACOMP on it with a gasket and it's hooked up so it shouldn't be a problem. I am still going to remove it though.

Before I hook up the return don't I need a bypass style regulator? Or do I just hook up the return from the carb straight to the fuel tank?

I still haven't figured out what the open port next to the fuel input is (right to the left of the air vent solenoid valve). It's open to the atmosphere but I will cap it as you suggest. I had the car running yesterday (it was warmed up) and every time I blocked that port off the car died.

Same with the air vent solenoid, it has a single wire going to it with a molex connector on the other end. Thinking I need to supply it with 12v as per suggestions on this forum. Thoughts?

I appreciate all the help you guys are giving me.

Because you can tune and change the entire carb. You can change all the jetting and chokes and the Nikki carb will only flow so much and the chokes cannot be changed. If you want to drive to the grocery store, keep the Nikki. If you want all around performance get an IDA carb. Hands down best carb for a rotary and I have tried them all.
Let me know how the Nikki runs lol

This is a very budget race car. I paid $3,000 for the car (working somewhat) and all the spare parts. I can't see spending $600+ on a new carb and intake manifold to get a 12a running well. I'd rather spend the money on a 13b with fuel injection swap if anything. I've got a 2-barrel Mikuni PH44 and it works fine, it's just hard to drive. Anything below 4k and you have to lightly feather the throttle or it bogs and dies, after 4k do whatever you want and it runs amazingly. The nikki allows me to get time on the track and work on my driving without having to have perfect throttle control. Same reason I am keeping the vacuum secondaries and not swapping to mechanical secondaries.

Is the sensor under your fuel inlet and outlet plugged in? If not then you have to cut out the plunger to get it to run right. For the fuel return just put a new 1foot piece of fuel hose there. It looks like someone goofed up and tried to put a filter there. And hooking up your advance will help you drive smoother and faster unless you go forced induction.

If by plugged in you mean supplied power, no. There is no power going to it but it is still installed in the carb. I will re-wire it to the hot side of my ignition switch (military style toggle switch) so it gets powered when I go turn the ignition on.

Only cut the plunger out if you dont plan on having it hooked in or dont hve the wiring.

There is still the original wire with the molex connector on the end of it so I will just snip the connector off and solder/shrink a lead to the ignition. Just picked up some 20mm freeze plugs and I am taking measurements for the ACOMP plate right now.

CAD

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CAM

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CODE

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CUT

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Got it all rigged up, just ran 12v to the solenoid straight from the battery to test it. It won't start anymore.

Messed around with it a bunch. I had the gasket between the throttle body and the rest of the carb flipped so I corrected that. It still doesn't start. It wants to. It turns over for a split second like it's going to start but doesn't. I had this thing running yesterday (with the gasket in the right way), even after all the mods I did to the internals, before making the changes to the acomp, fuel return, dizzy vacs, AVS, and the open port. I broke it down yesterday evening when I noticed the secondary butterflys weren't seating properly. Didn't change anything but that and the linkage on the secondaries.

The motor would kill when I would plug the open port to the left of the air vent solenoid

Hrmm... So I broke down the carb again, had to take it off to put my freeze plugs in.

Everything appeared to be put together correctly.

I was getting gas to the carb for sure because the accelerator pump was squirting fuel with each pump of the throttle (I may have it set a little too long) and the return line had fuel coming out when I removed the hose. I am running 3 lbs of fuel from the regulator.

I am not sure where my idle speed needs to be set to start out. Do the primary butterflies need to be open at all to make the engine idle?

The port that I have been trying to figure out goes to the same chamber as the air vent solenoid and I am guessing was performing that function while the air vent solenoid was without power, hence why the engine would die when I plugged it with my finger so that solves that mystery, now I just need to wire up the solenoid with 12v from my military switch (single wire input, grounds through the engine) and plug the port.

After all this I installed the freeze plugs then carefully and very slowly put the 3 parts of the carb back together.

I also took some vacuum pot off the intake manifold that was plugged up. I forget what it's called but the carb stripping manual said it was OK to take off. I will make a blocking plate tomorrow to seal it.

And you forgot to fill in the ACV port in the engine, right? Get ready for a super hot manifold now.

I'm not sure what that is. Nothing is back on the car yet.

Is that the thing on the other side of the intake manifold (opposite where it mounts to the engine)

This thing:
http://www.pineappleracing.com/Produ.../ACV-NA-1a.jpg

That's BEEN blocked off. Was blocked off since I bought the car. The nikki was fairly stripped but the guy who owned it before me had to leave certain things on for spec rx-7 racing.

you know you can tune it right?

If I had a jet kit. I don't have ANY parts for the mikuni. It's actually a VERY simple carb and was terribly easy to break down and put back together. God does it sounds good at high RPM and wot. I think last time I looked for a jet kit I couldn't find any for sale. I did get a gasket kit and I replaced the old gaskets so other than the jets it's reasonably freshly rebuilt (last year or so).

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Had it running as well

The ACV port(s) allows heated exhaust gasses to pulse into the intake manifold, thus heating it up. It's an emissions thing and so must always be blocked off whenever you do freeze plugs in the rotor housings. You see, the coolant actually keeps the manifold from getting too hot. Interesting, isn't it. :)

Yeah, that's been blocked up. This nikki got stripped a long time ago.

Looking around for parts for the Mikuni. I think I can get some jets from Wolf Creek Racing... Not sure where to even start though and their are 20 or so different sizes...