gilmore03

my buddies got a 83 gsl i sold him...I always ran 93 in it, and he put 87 in and he never let the car warm up fully (manual choke). He put the 87 in let the car cool down started it up and pushed the choke in. The car ran like **** and before he even called me, he thought the carb was fucked up so he tried adjusting the carb. Ever since he did that the car is running like crap. When the car is fully warmed up and idleing it sounds fine but when you rev it its popping really bad out the exhaust, the higher the rpms the louder and quicker the pops get. The cars got like no power either but i dont think its a blown seal. How do you adjust the carb? and how are the order of the ignition wires suppose to be? How can i tell if its really a blown seal?

Rogue_Wulff

I'm betting on a vacuum leak.

steve84GS TII

Non-turbo rotaries LOVE cheap gas.87 octane fuel is all they need,the good stuff should only be run if your boosted.

It sounds like you have the plug wires messed up,or possibly the leading ignitor has failed(which is very common).Its not a good idea to mess with the carb unless you have mods or it needs a rebuild.Since your symptoms came on all at once,Id say its something simple and common like the ignitor,a split vacuum hose...something like that.

Heres how the sparkplugs are situated looking from the drivers side of the car......

TOP
T1................T2

L1................L2

BOTTOM

trochoid

iTrader: (6)

I agree on the vacuum leak too, here's why. A vacuum leak leans out the fuel mix, with running 93 octane, that may have helped mask the leak by putting the fuel mix near where it should be. Your friend needs to put the carb back to the original settings, start looking for vacuum and exhaust leaks. The car may have both. Checking timing wouldn't hurt either.

If it's substantially down on power, the exhaust system may be plugging and blown out somewhere. Fyi, 93 octane is a waste of money, an NA will run on a much lower octane than the 87.

K-Tune

iTrader: (26)

sounds like ignition, and possibly a blown ignitor. hes also going to need to reset the mixture and idle on the carb.

aussiesmg

iTrader: (1)

93 is a complete waste on a rotary, they don't have big compression numbers so why the higher octane.

SunRedRX7

Per Felix's FAQ.

http://mrmazda.no-ip.com/cfaqtext.html#ROCTANE

What's the best fuel for my rotary car?

It depends. If your rotary Mazda is equipped with a turbocharger, all the normal rules about octane apply. Use the highest available octane premium fuel for best power and best protection against the ravages of detonation. You may find slighly better fuel mileage using lower octane, but you need to be very careful about using the available power on lower octane. If you are good at exercising restraint, you can save a little money on a long trip using regular, but it's probably best to stick with premium for normal use.

WIth the NA rotary, the highest octane you should use is US pump (AKI) 87, typically RON 91 outside the US, no matter how heavily your engine is modified. Octane in excess of any engine's actual requirement is always wasted. The issues of purity and additives in more expensive fuels are entirely separate issues. There's no reason not to want either in a NA rotary.

The rotary engine's high turbulence combustion chamber provides a very high resistance to detonation. Its duration of combustion is also longer, remembering that the rotors turn at 1/3 of the tachometer reading, and the slow burn* of high octane is undesirable in it. Pump 80 octane is more than sufficient for most of them. Best power and mileage are usually produced with the lowest available octane.

Many serious rotary racers bring their own low octane gasoline to tracks that supply only racing gasoline. From "How to Modify Your Mazda RX-7", by Dave Emanuel and Jim Downing, HP Books, 1987, ISBN 0-89586-383-9, p 47-8:

". . . the best results are obtained with conservative spark-lead calibrations provided the engine is fed a diet of low-octane fuel. The fact that both 1985 and 1986 IMSA Camel Lights championships were won with low-octane fuel is a rather definitive statement . . . ."
So if you want best performance from your NA rotary, you want lowest octane. The lower cost of it is a nice bonus.

* Note - the time allowed for combustion at high RPM is measured in ten-thousandths of a second. Some literature ascribes lower volatility rather than a slower burn as the characteristic of a higher octane value. In contrast, consider the following: From "14-to-1 compression", By David Green, NASCAR Winston Cup Scene:

"One problem that has developed in the 9.5-to-1 engine is high exhaust temperatures, due to a less-efficient burning of 108-octane gasoline in the lower-compression combustion chamber." (emphasis supplied)
For more information on octane/antiknock characteristic:
Octane Determination, by Gregory Travis
The autos/gasoline FAQ, by Bruce Hamilton, or its mirror.
Chevron's "A Consumer's Guide: Gasoline Octane for Cars"
Mobil's "Gasoline Product Knowledge"

trochoid

iTrader: (6)

In all the reading I have done, I have yet to find exactly how low of an octane they actually ran. I know at the time is was a closely guarded secret, but come on, 20 years later somebody could at least spill the beans.

dgriff

ive always heard 80.

Rx-7Doctor

iTrader: (13)

#1 rule on driveability issues. LEAVE the Carb alone. When you believe you have to adjust the carb, it's usually to mask another running problem. As Trochoid has stated might have exhaust blockage on power problem. Also verify that the secondary linkage on the carb is still attached.
Recommend verifying leading ignitor is working and performing compression test. The usual suspects on power loss are still the following. 1). Compression 2). leading ignitor failure 3). blocked fuel filer. 4). restricted exhaust 5).Carbed motors where the secondary linkage spring has popped off. On the possible leak, check around the ACV if still there for leakage, if that gasket is leaking you will have alot of popping and low power.

perfect_circle

about you guys saying you only run low octane on the na's, well the turbos actually love it more, its just not as safe....although the tii does say to use 87.