I've had my SA22 since new and I've been running the same type of NGK (or Denso) plugs for the whole time, with 1 exception. The first time they were changed out, the non-Mazda mechanic used Champions. They lasted for about 75miles. Are there any other plugs that work well (or even better) in the Thermo Reactor cars?

Also, the twin coils are the originals. Is there an appropriate replacement available?

Thanks, Herb

 

Herb,
You don't mention if you have a 79 w/points or an 80 with electronic ignition. You can upgrade to the electronic ign. fairly easily if desired. Throttle responce is noticabliy quicker. Nothing special about either set of coils, but they are different I believe. I've never found a plug type that works better than OEM style. But now a days, I'm more into cruising than leaving burning trails of tire tracks.

 

I'm keeping it bone stock including the points. (sentimental). What specifications do you use for coil replacement? I remember putting a high performance coil on my 59 Sprite years ago. It melted the plastic around the points.

Herb

 

i rebuilt a points distributor for my old 79, just because. the 81+ electric system is WAY better.

anyways here are a few off the top thoughts about how to get more ignition power.

condition! the ignition can only put out so much power, and there isn't much headroom so things like the cap and rotor and wires need to be in excellent shape. the wires need to be under 16k ohms/meter, and new wires are about 6-8k.

secondly since the power that comes out is directly related to the voltage in, at minimum the contacts for everything should be as good as you can get em. on the race cars we used to run the coil power right to the alternator, because 14v is better than 12v, and the points cars are easier, you could bypass the resistor so it runs 12v instead of 9v. however i'm not sure the points would put up with that.

third, the race and Rx8 style spark plugs take less energy to fire than the others. its expensive, but the Rx8 plugs are the same heat range, and they do run better

 

I've looked some and the only spec type information I found was in the back of the 79 factory service manual as follows:

Leading Coil, Type: HP5-13J, Primary Resistance: 1.4 Ohms @68 degrees, External Resistance: 0.7 Ohms X2 @68 degrees

Trailing Coil, Type: HP5-13J, Primary Resistance: 1.5 Ohms @68 degrees, External Resistance: 1.6 Ohms X2 @68 degrees

 

Herb
-here:
http://www.racingbeat.com/RX7-1975-1...ion/11530.html
is prob the definitive discussion on RX7 plugs, of which they recommend exactly ONE. The one you have been using? Its what I use in my 80 SA without issues.

If you stay stock on your ignition then the NON electronic ignition-spec coils are what you need.
BlackDragonAuto.com sells Bosch:
http://www.blackdragonauto.com/icata...l.aspx?Page=92
so those are spec'd for 79 RX7 only. Or you can pay the piper at mazda, just make sure the Kid Behind The Counter understands the 80-85 coil WON'T work!!

As others have hinted here, the 80 or the 81+ electronic ignitions are FAR less maintenance than the cobbled 79 system - I mean, jeez, all those relays and doo-dads REALLY necessary to get spark to an engine? You can have great points set-up etc but if any of the way-too-many electronic boxes the 79 soldered in there goes funky you will never be able to chase it down. And after 33 yrs, you know the clock is ticking...
Anyway, lots of archive material here on how to do it should you reconsider...


Stu Aull
80GS
Alaska

 

Thats a good find Stu. According to Black Dragon, the Bosch Super "RED" Coil P/N 80-104 is the correct Bosch replacement for the 79 OEM 1.4 and 1.5 Ohm coils w/external resistors in the 1.4 to 1.8 range. Herb, a possibile replacement from the stock ones if you wanted to try.

These aren't as cool sounding as the "Flame Thrower" 1.5 Ohm ones offered for the electronic ignition cars. Stu's right you can't interchange them. Even the 1980 factory service manual shows them as a different model number then the 79 manual. FWIW, I'm keeping my 79's sparking with the old school "chattering teeth" points method too. The electric spark rev's like a banshee, but thats not the way I play with my toys.