Dear Paul

 While searching Fleabay for something to buy, I saw a 12A engine
 with dual distributors and a 4-barrel carby for sale. I have never
 seen a rotary with 2 independent distributors, and am seriously
 considering buying the engine, specifically because of this
 (potential) dual ignition system. Do you know these engines? It
 would make a nice little p-port with a dizzy per rotor, and a Holly carb
 with leaning block and turbo.

 Erik in Oz.

 As I recall my 1973 12A RX2 had twin distributors. Maybe early RX3
 also. It was easy for Mazda to do that as an off the shelf piston
 engine distributor would work. Only the rotor caps were different.
 Similar to my rational of using one megasquirt per rotor. The twin
 distributor front cover will probably bolt on a 13B. With modern
 electronics no distributor is necessary. You can trigger off the
 front pulley or the ring gear.

 Nice collectors item if you are restoring an RX2. Only about 120 HP.
 Not a good power to weight ratio by todays standards. Not a good
 aircraft engine as Mazda made some significant improvements in
 materials in 1989.

 Paul Lamar


 The early engines had dual distributors, one for the leading plugs and the
other for the trailing plugs. The distributors had a L or T cast into the
housing to differentiate. The plug wires had different color boots also for
ID. The distributor caps and the rotors were different for a piston engine. As
shown in the photo, the coil wires went in the center and the two plug wires
went to the two leading or trailing plugs. You had to get the 1 and 2 rotor
positions correct as with any engine. The rotor had two ends that could
conduct to the two terminals that are 90* apart thus giving the correct firing
with the distributor turning 1/2 engine speed. Mazda went to a single
distributor for the '74 model year. There was also other engine design changes
that are desireable. The side seals were reduced from two to one. The Canadian
1973 RX3 I owned was advertised at 110HP. The JDM cars had 130HP but did not
have the emissions controls choking them. They also had a freer flowing
exhaust that was like a regular manifold, not a thermal perverter. I was
getting 18/21Imp MPG from my RX3 until I got "lean jets" for the carb from
Racing Beat. The emissions used large jets to put a rich mixture in the
combustion chamber and the air injection and thermal reactor supposedly
cleaned it up. In '73 a Chev 1/2 ton with a 350 engine got way poorer fuel
economy than one with the 454 engine. The big block was determined a medium
duty engine and did not have to meet the same emission standards.
As Paul stated, a great engine to restore an older car.

Dale Davies
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