cletus

I'm thinking of changing carbs, but I'd like the car to be street legal still. Stupid Atlanta emission requirements. I was told swapping carbs would make it so it would never pass emissions again.

Thanks.

85RX7GS

iTrader: (1)

You could try a Holley carb kit. To pass emissions though, you'd probably have to have a stock exhaust, so I'm not really sure why you'd want to switch the carb, as a carb and exhaust upgrade would increase performance, but make the car fail.

moremazda

iTrader: (4)

Do you have an under-hood visual inspection to go through?

peejay

Probably not, unless you stick with a modified stock carb.

85RX7GS

iTrader: (1)

I think there is a website out there that has a procedure to modify the Nikki Carb. It's on http://rotaryactive.tripod.com. Check it out - there are pictures as well.

SilverRocket

As far as I've ever seen, no aftermarket carbs retain any provision for emissions equipment. Hell, some of them don't even have a port for the brake booster!

Your only option is the Yaw modified Nikki as far as I can see. Check if you can run a header and hiflo cat. Otherwise, if you're running a stock manifold I don't see why you'd want to invest in an aftermarket carb because you won't make any power.

cletus

No visual inspection. I'm having major issues with the nikki that is just annoying the living crap out of me so I'd rather just swap that out then deal with modifiying the nikki. I don't know enough about carbs to pull off what would need to be done. BTW, that webpage is also pretty jacked Just a bunch of tripod pictures. But I've heard of some things I could do and it seems beyond my scope.

It isn't about power at all. It would be a nice side affect though. I do have a high flow cat on there to my knowledge anyway from what I remember about looking through the records. It passed last time no problem. It's more about being able to go around a corner and continue being able to drive.

But where would I even start looking for aftermarket carbs? Most likely either a holley or I guess I could go with a Yaw modified. The yaw could be the answer. Like what place sells the holley? (Not sure where to go about in finding out how to get a Yaw either). I may just end up registering the car where emissions don't matter, so I'm looking into this route as well, but just in case, I was taking a stab at keeping it legal.

SilverRocket

If what I'm getting from you is right, you're saying that power is not the main concern, you just want your car to run well and not have to mess with carb problems. Well, if that's what you're looking for I'd stay far away from aftermarket carbs, except possibly for the Yaw. All aftermarket carbs reduce driveability significantly over stock - remember, the significantly increased power they gain often comes at a fair compromise! The 2 barrel carbs in particular make little in the way of low end power, which means you must downshift to pass, etc. It's usually all about the high end. As well, you're likely to have a lot more trouble getting them tuned properly than you are with the stock Nikki.

Remember, most anything you do with your car to make power will result in it not passing emissions

From what you've said, I'd recommend you just get your Nikki expertly rebuilt by someone who knows what they're doing. I wouldn't send it to Yaw and expect to it back anytime soon though... although his carbs are reputed to be absolutely fantastically done, from what I've heard the turnover time is a few months at best. It'd be best to buy another carb and send that to him.

As for the Holley, RB is the only one that sells it extensively modified for the rotary. Don't even think of buying any other Holley if you're not looking for big troubles getting it running. It's very expensive though, and it won't make good power without full exhaust, upgraded fuel, etc. Holleys bog down in hard cornering as well, that's another consideration if you're into handling.

Again for you I think a good rebuild might be the ticket. That's just my 2 cents.

cletus

Here's the thing that is making me rethink a bit more.

My engine actually completely dies if I corner too hard. But it isn't immediate. It is about 1/8th a mile up the road it will die. And it takes about 30 seconds of turning her over to get her restarted again.

The question I am presenting now is does the typical "stumble" from hard corner normally happen immediately or is it delayed like that? Mine seems a bit more advanced since it isn't really a stumble

I'm second guessing my first impression. It almost seems like whenever I do that, maybe something is happening that fuel is no longer being picked up from the tank and I'm actually running on my fuel line for a minute and then that's dry and I have to get fuel all the way from the tank up to the engine. She does not act flooded at all. Obviously, once I get her started again, she runs normal until I **** her off by cornering too hard again

This is just frustrating me a bit. Topped with my lack of carb knowledge, it's irritating.

Thanks for the help again guys.

SilverRocket

I don't believe that my car stumbles at all like that, and it certainly never dies! Does this only happen with a low tank of gas, or all the time?

Have you checked over your entire fuel system? I know next to nothing about carbs, and I'm not sure what in the stock carb could cause this. I'd suspect your fuel pump first, try doing a volume or fuel pressure test (Haynes manual or search the forum). Also be sure to replace your fuel filter before doing anything else, if you haven't already.

There was someone a week or so ago that was talking about this exact thing, and a forum member said they had a fix for this if it's happening at low tank levels, but it was an autocross secret and he'd email it to you. You might wanna do some forum searching. Sorry if that was you and I have a bad memory lol.

cletus

It may have been me. The fix involved more carb knowledge than I have. I'm poking around for a 2nd stock carb in this area and may take a stab at it. If I have the 2nd carb, who cares if I screw it up, right?

Unfortunately this happens at all tank levels. At first I thought it was the filter being clogged or something, so I swapped that. Obviously nothing. The previous owner put in a 9psi holley pump, but I guess it could be dying. That thing should be overkill though. I have a crappy purolator regulator on it, the holley regulator is in the mail.

I mean it is pretty bad just to have the car die on the street (or more often on the autocross course). Potentially dangerous too. It's just frustrating more so though. I may have to get smashy soon

Thanks again for entertaining me

SilverRocket

No problem, I'm not much help since I know very little lol, but I figure learning about others' problems and their fixes is a great way to learn yourself. Also, often a simple conversation with someone who isn't an expert either can start you on a different train of thought and eventually illuminate the problem.

Does turning up the fuel pressure have any effect? I know those purolater regs are supposedly very innacurate. I wonder about that pump you have too. Did you order the Holley pressure guage as well as the FPR? I'm actually thinking of getting that FPR and guage when my FB comes out of storage soon.

Concerning the guages and this kinda problem, I wonder if an in-car guage might be of great assistance? I'm sure it's way more expensive to do it that way, but it would sure be neat to really know what's going on.

cletus

I actually enjoy this stuff, but I really enjoy solving it more

We actually tried the whole upping the fuel pressure at the regulator to see what happens. Before I changed my filter, nothing hapeened. After I changed it, when I upped it, the car flooded.

I'm thinking I'm going to drop in an air/fuel meter and get a decent pressure gauge on there eventually anyway. An in-car would be interesting, just make sure you don't have a leak or anything .

SilverRocket

Does she bog cornering both ways or just left/right? I don't have a clue what the significance would be, just a dumb idea.

I'd love an air/fuel guage too, but I'm a broke student and I don't want to pay to have an oxygen sensor installed.

I don't like the idea of fuel inside the car, I wonder if theres a way you could install a fuel pressure 'sensor' and then run the signal into the car... I haven't done any research on this so I'll stop talking out my *** now lol.

Good luck getting your car ripping the corners again!

cletus

I haven't yet found a correlation between direction of the corner and it dying. It's happened on both left and right handers (I think anyway, like I said, it takes a while until it dies, so it could be a few corners until it actually dies and I could be thinking of a different corner that the one that actually caused it).

And I get no actual bog until right before she dies. I may get it a few times, but it is a good distance from the actual corner (about a good 1/8th of a mile or so on the street, who knows on the autocross course, too many turns). I never actually know if I cornered too hard or not until suddenly a bit later she is dead.

This is just weird.

SilverRocket

You could always just become a drag racer

RXcetera

Your carb could be overflowing and flooding the engine after hard cornering... Try braking HARD and seeing if this also kills the engine.

Other possibilities are almost endless... but try observing your carb when it's running properly and when it wont start. Knowing if you have too much fuel or no fuel at all in there when it wont start would be a good start...

cletus

Braking hard doesn't seem to affect it at all (and I have tried).

The only thing I am thinking is if it was flooding or something, wouldn't it die quickly instead of the roughly 20 seconds later? I seriously don't know this answer. My carb knowledge is kinda crap.

Ok, so what are the first steps to making it a drag car?

SilverRocket

I think you need to find a friend like RXcetera, because whenever he steps within the near vicinity of my carburator it runs flawlessly. No kidding, he so much as touches the thing and the problem I was beating my head against the wall about magically disappears. They love him or something. You need to find someone like that

RXcetera

Thanks buddy .

cletus

How much are plane tickets currently? May be a cheaper way out of it

RXcetera

I was just in Georgia... it's about a 18 hr drive .

cletus

Ok SilverRocket, this one may be interesting. I went ahead and got the holley FPR to replace my crap one, so I needed to get a fuel pressure gauge I could use to set it. Did a little reasearch and they do have in car ones pretty readily available. The electric ones from autometer went for $180. But they had mechanical ones that have something that goes with it so either fuel never enters the car or it's some sort of shut off thing so if there is a leak, it shuts off. It's called an isolator, go figure. So I decided with the fuel issues I've been having, it would nice to monitor pressure when I'm cornering and such so I went ahead and go the mechanical. It went for $90 including the isolator which isn't really horrible. Oddly enough my little quartz clock just died for some reason, so I'm just going to go ahead and put it there. Should be intriguing.

SilverRocket

Very interesting! Sounds like a great idea. Just be sure to tighten those fittings down real good lol.

The way I see it, it could shed a lot of light on your problem - if your pressure is measured before the carb and it drops off when you experience your stumbles, you'd know it isn't a carb problem. But if it doesn't drop, your carb could be flooding like RXcetera suggested. Or at least that's my uninformed interpretation lol.

I'm picking up the same Holley FPR this weekend, but since I'm a broke student it's gonna have to be the regular guage for me (only $40 Canadian). Incidentally, I'm also ordering that Grose jet I showed you from Mazda Motorsports. I don't really need it, but I'm re-jetting my carb anyways and I might as well pop that in while I'm in there.

Let us know what happens when you get that **** installed - should be pretty cool