falcoln0014

I bit the bullet about a month ago and ended up ordering the rotary shack "40+ mpg kit". The kit came with a Weber 34 (1 barrel carburetor) bolted onto a very nice (I believe to be MIG welded) metal manifold adapter. Robert also sent a throttle cable adapter which we had to weld a piece onto in order to keep it from bending in half. More on that later.

I generally don't post anything, but my mileage is horrible. I need some ideas on improving it.

Robert sent me a jet that was supposed to lean out my carb, but according to the 34 ICH diagrams it's actually the idle jet. I don't really see how that would have much of an effect on my mileage. That and we were going from a 70 to a 50, but it apparently already had a 50 in it. I need to call and ask about it tomorrow.

Also on the note of the idle jet I have to keep the A/F screw tightened all the way in to get a smooth idle. I don't know what that means, but I assume it's not good. Anything past about 1/2 turn and it starts to miss a bit, but by 1.5 turns it's all over the place. RPMs drop quite a bit when you turn it out (counter-clockwise), but raising it to 800 still makes it idle like poo.

My first tank with the carb yielded 15.821 MPG. That's roughly 60 miles in town and 60 on the interstate. At this point I have a few vac operated things hooked into the carb adapter plate. All of the things re-routed in Carls nest removal tutorial (vac advance, odd white pot, cruise, etc).

After talking to Robert a bit he told me I should have the remainder of my emissions capped/removed, so I did that and ran pretty much the same trip i did before.

This time I got 15.449, so a very tiny difference if any. My car is running rich, but not nearly as rich as it was with the Nikki. This last year my Nikki was getting around 8-9 in town and 13-15 interstate. I had suspected a vac leak, but I can now confirm that is not the case since every vac port to the carb is capped tightly.

I'm guessing the vac advance (or whatever the two pots on the dizzy are) isn't very important on a weber setup. I do have one question about it though. If I don't have it hooked to the adapter plate do I need to have the hoses coming off the dizzy capped? They currently are, but I'm reading mixed things about that.

Now, a few of the mods I have on the car:
1) DLIDFIS ignition upgrade (3 gm hei modules, 3 MSD Blaster 2 coils, trailing through leading on dizzy)
2) Rats nest removal (everything is capped and extra belt installed on main pulley)
3) no cats on the exhaust (aftermarket 'muffler')
4) replaced the fuel pump (if that matters...I believe it was a carter).

Tires are on stock wheels and air pressures are usually between 32-34 psi. Transmission and rear end are both stock (5 speed manual). AC system was also gutted which had me up to 24mpg interstate at one point.

The engine itself has under 30K miles on it. I believe it was from Pineapple Racing, but it's been a few years. Compression was over 120psi on both rotors, so I don't think that's the problem.

Two things I do wonder about are my timing and exhaust.

I know my exhaust has leaks in it, because I get horrible backfires sometimes when i shut off the engine. It seems to be about 50/50 and it can range from a loud pop to a fireball that lights up the entire side of the house. Needless to say, I doubt the neighbors are amused.

I'm fairly certain the guy who installed my motor (because of warranty issues) set the timing correctly, but I'm not sure if he took my DLIDFIS into consideration. At the same time I'd like to check it myself, because he left a number of key vacuum lines unhooked.

As for the timing I have a plain jane timing light. It says 'Innova 3551 timing light dis-conventional' on the back. The only button it has is to turn the light on and off. I just want to see if my timing is advancing correctly around 4k, so I assume this will be fine?

I'm going to link up some pictures on here as well. These I'm going to post now are from the day we installed it. They show the kit before I installed the throttle adapter and cable. Which is something else I've been having problems with. I've had to install a fairly heavy return spring to keep the throttle closed. Even after applying WD40 and gear oil to the throttle cable on both ends it still sticks. It sticks so much it's like I have cruise control again. Cruise control that sticks at a permanent 4000 rpm. :P

I've also cleaned out the engine bay a bit since these were taken. More pics soon.

Partially uninstalled Nikki: http://psychoticstudios.net/photos/a...l_IMGP5601.jpg

Partially installed kit: http://psychoticstudios.net/photos/a...l_IMGP5611.jpg

Closeup of kit (breather not included): http://psychoticstudios.net/photos/a...l_IMGP5609.jpg

You can see the rest of the install here (and more photos as I add them): http://psychoticstudios.net/photos/t...s.php?album=51

Kentetsu

1. The lines from the dizzy vac advance do not need to be capped. The dizzy does not produce vacuum, so there's no point other than possibly keeping the vacuum pots clean and free of debris.

2. When you installed the Carter fuel pump, did you also install a fuel pressure regulator? If not, then the pump will simply overpower the carb and cause it to run rich.

3. More of a question than anything, but did you give Rob a decent opportunity to work with you in correcting these issues before posting here? That would be the "nice" thing to do, but if you did and he has not been able or willing to assist you, then that's a different matter.

Good luck, and keep us posted on how the carb ends up performing...



.

Sterling

I agree with Kentetsu on the fuel pump over powering the carb, and especially on point #3.
Also, unless the emulsion system inside is blocked up, the Nikki is basically incapable of getting 8 MPG with the stock jetting at normal fuel pressure.

t_g_farrell

iTrader: (1)

My advice is to first make sure the fuel pressure is regulated to ~3.5 psi or the carb
will always run rich and/or flood. Even a nikki would need a regulator depending on
what model Carter you have. I suspect your running too much pressure. In your pics
I don't see a regulator in there. Get a good one, not one of those cheapie Mr Gasket
things. They don't work well at all.

Also make sure your timing is correct. Use the OEM settings at first. Make sure theres
no vacuum leaks. Get a vacuum guage and verify that the vacuum you see is rock steady.

The reason Robert probably sent you a new idle jet is because on webers (well
most progressive two barrels) the idle circuit dominates the AF mixture at partial
throttle and doesn't stop affecting the mixture until WOT occurs. So the right idle
jet will make all the difference in the world.

I hope your having these kinds of discussions with Robert as well.

diabolical1

iTrader: (3)

check and re-check the timing before you do anything else. get a regulator and make sure your ignition components and fuel filter are up to snuff.

falcoln0014

Robert has called me multiple times in the last month to help with the install, so I'm certainly not trying to say/do anything bad in regards to that. I just know that 3 or 4 heads are often better than one or two. :P

I'll check around town for a regulator today, because that actually makes sense. No matter how much we leaned out the Nikki (any of them I had for that matter) they always ran rich. Might also explain the explosions/excess fuel in my exhaust on shut-off.

Why is it that 90% of my problems end up being something overly obvious and simple? :P

Kentetsu

Here's a link to a writeup on the installation of a Carter fuel pump and Holley regulator. Might help out a bit...

https://www.rx7club.com//showthread.php?t=529605

falcoln0014

Got an in-line regulator installed. The gauge is showing 2.5 PSI and I drove around a bit to see if it changed, but it seems to be staying around 2.5. I've also been reading on the forum how inaccurate these things can be, so I may install the regulator and dial it down a bit just to see the difference.

Also, the jet I thought was a 50 was actually a 70. It was apparently bored out and I didn't think to look at the actual hole sizes on the two jets. I just read the numbers on the side that said '50'...my bad. :P

Switching the idle jet from 70 to 50 seems to have helped quite a bit my idle/starting. At first it didn't want to idle at all, but I dialed the A/F screw out a few turns and it idles fine now. Much better than having to turn it all the way in.

I've also got that fuel pressure regulator out in the car. Robert said I could improve my gas mileage by dropping the pressure a bit. How does that work exactly? I had always assumed the jets you installed dictated the flow/quantity of gas, but that doesn't seem to be the case. If it was then I wouldn't be bothering with a pressure regulator at all, would I? :P

Also the timing is still questionable. I'm going to see if I can get the timing light working later, but Robert suggested I just advance it in small increments and see how it drives. Right now the nut on the dizzy is about 1/4" or so from the left. I think that is slightly retarded.

80's old school

iTrader: (7)

Well you have been talking about gas mileage....how is the power? Driveability?

falcoln0014

Smooth and responsive all the way to 8k, but I usually just go to 6-7 before shifting. The misc Nikki's I had didn't really take off until around 3k and then would bog out a bit before 7k.

Power wise it's hard for me to tell how much different it is. Having no secondaries means I can't really feel it 'kick in', but I would say it's every bit as peppy as my Nikki was (if not more due to not bogging out).

I can tell you it'll still squall the tires. Even after making a turn if I slam the accelerator down it'll squall (which I'm sure doesn't help my gas mileage... :P). It's actually much more responsive without the huge return spring I have, but it sticks at 3-4k sometimes when you let off (like an un-wanted cruise control). I'm really starting to think my throttle cable is bad/damaged. Might try hitting it with a little more WD and gear oil later.

Another nice thing is it returns from WOT to idle without backfiring. All of my old Nikki's did...especially if I was going downhill. I think that probably has something to do with my plethora of exhaust leaks (or running a straight pipe to the back for a while).

The wife always thought my car was about to explode... :P

racerlinkfc

ROTARYSHACK 1BBL carb kits rule!!
i love mine good power and great gas mileage.. these will replace all nikki carbs eventually.

84stock

iTrader: (5)

I would really like to hear/see some true 40mpg out of one. Robert is not one to screw someone out of $$ on a product design, so there must be hope here.

680RWHP12A

the rotaryshack 1bbl intake kits can deliver the much improved fuel economy, smooth drive ability, improved starting and great low end torque. but, and here is the catch, only if your fuel system, ignition system and exhaust system is working properly.
i have sold over 30 kits since i started selling them and everybody is happy , for the most part.
if your motor is blown, you have clogged cats or your timing is wayyy off, or your running 4.88 gears in the rear end dont expect 40 MPG

680RWHP12A

your going in the right direction
the fpr will help the fuel not bypass the needle valve causing your car to run rich

Siraniko

iTrader: (13)

do I need to send you some cheese or bitches so I can get a Weber 34???

84stock

iTrader: (5)

This is common sense i agree, op needs to get the exhaust fixed and control fuel and timing and post new results.

Jeezus

iTrader: (4)

Hope everything works out for you, I always wondered how that carb setup worked!

8mpg in a nikki!?! I got 34mpg in the city with mine....

thunkrd

iTrader: (1)

stu.... how the hell do you get 34? i'd kill to get 34 mpg haha, maybe i should use a carb instead of stupid FI from my SE which gives me about 18

falcoln0014

At 8 it's hard to tell if you've got a gas leak, or if it's running 'good'. :P

Riding with the windows up isn't an option unless you want to die.

Kentetsu

The issues you were having with your Nikki were most likely due to the fuel pump you added, combined with the lack of a regulator. You can't even jet a Nikki to get that kind of mileage. The only way you could get those results would be by cramming way too much gas down the throat of your poor carb....

Good luck.

RX-7 Chris

iTrader: (19)

wow 8mpg on a Nikki, can't say I've ever seen one that bad. I'm getting 19 city and 26 highway with my SP holley setup.

falcoln0014

I think it was the jetting. The last carb was an older Yaw modified model. When the engine was replaced (probably 5 years ago or so) I was told the internals were pretty much shot. He replaced the already larger jets with even larger jets. At least I wasn't running too lean? :P

I kept putting off replacing it for...a while. Then when I got 8ish mpg (and tired of smelling as fumes at all times) I figured the time to put it off was over.

I may install the regulator later today, or possibly Sunday. We're taking the wifes Sentra camping since nothing fits into the 7.

Jeezus

iTrader: (4)

https://www.rx7club.com/showthread.p...ht=hypermiling

rotarygod

iTrader: (1)

Wait a second. These kits completely block off the secondary intake ports? Completely? How do these engines still make power?

Sterling

-They don't.