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 probaly 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
I don`t think this engine is going to sell, so I plan on offering
the owner $300 for it. I am only looking for around 120 hp. anyway
so the plan is to p-port it and add a carb with a turbo for 140 take-
off hp. I am too stupid for fancy electronics, anyway. Most of the
megasquirt discussion you have going at the moment is way over my
head. I like the 2-distributor redundancy and the carby reliability.
At least I know how they work...:)
If nothing else, I will have a working 120 hp. p-port engine for
not too much money. Would I still find parts for this engine?
Erik in Oz.
Rotor housings might be a problem as I think Mazda quit making 12A parts
quite some
time ago. Rotor housing are high pressure die castings and very
technically
sophisticated and not easy to make. The wear surfaces are chrome plated
hard steel.
Regards,
Erik in Oz.
Hi Paul & All;
I also have a 12A engine I built for a Coot amphibian I was building,
But I gave it up because of getting older and not wanting to mess
around in the water. I sold the airplane parts but the buyer didn't
want the engine.
It has the two distributors which makes it easy to set the timing on
the two sets of plugs. I used two TRW Electronic modules with them.
It has a turbo off a small Buick V8 of the day and it works fine
with a poppet type valve for the control. It also uses a marvel
aircraft carb with mixture control. It has about 30hrs of test
running on a test stand on a trailer. The highest I ever ran it was
at 4000 rpm at 40 inches of mp and I thought the trailer was going
to take off. It has a set of gears from a Power Glide trannie with
1.87 reduction. It is easy to get it to run in reverse at the same
ratio. I looked all over for some gears and at the time I couldn't
find any thing better. Dragsters of the day of 1200 hp used those
gearboxes so I thought they ought to work ok. I worked out a bunch
of problems I ran into but I cured them.
I also have a Hartzell 92ZK prop hub with SEA-BEE blades cut down
to 74 inches.
If any one is interested just let me know. I have a lot of photos
from building to running.
Regards
BOB San
RX7 Specialties in Calgary, Alberta, Canada makes 12A housings by narrowing
13B housings. The early housings had a problem with the housings eventually
compressing in the combustion area and developing a coolant leak which let
coolant into the combustion chamber. This wet the plugs and it would not start.
Dale Davies
That is why Mazada changed to a high silicon alloy around 1989.
Paul Lamar
-Paul and Dale
Would it be as easy as narrowing a 13b housing (on a milling machine, I presume)to
12a specs without any other changes?
Erik in Oz.
Sounds OK to me. It is only 10 mm off each side as I recall.
The hard part is you need an NC mill to put in new O-ring slots.
That is the expensive part. Somebody has to pay the purchase price for the NC mill.
NC mills are not cheap.
Paul Lamar
-
The Rotary Engine News Letter. Powered by Linux.
ACRE NL web site. http://www.rotaryeng.net
You Tube key word PaulLamar2
Copyright 1998-2012 All world wide rights reserved.