"big snip"

Cracks have been known around the spark plug holes

On the exterior of the housing or internally? Royce

On the inner surface. PL

Mazda themselves removed metal
from around the spark plugs on the late turbo rotor
housing by a simple single cut of the mill on both sides.

Do you have a picture?
Royce

No I don't Royce. They just removed part of the web tying
the inner and outer walls together. At first, in the early
93 engines, they put the web in. Then later, in the late 90's, they
took it out with the milling machine. I think all new
rotor housings have the web milled out.

I know the one on the left is a early 93 as it has a knock
sensor just above the upper spark plug.

Here is a picture of an old rotor housing on the right showing
the missing web and then the web was replaced in the early 90's
on the left.

It will be interesting to see what they did in the RX8 engine.

BTW Everybody, if you have a junk rotor housing that has been
severely over heated cut it apart in little squares around the
spark plugs and see if the steel liner has separated from the
aluminum water jacket. If you don't have a band saw send it
to me and I will cut it up.

Paul Lamar

Went and looked at my 81' 12A housing and they have the webs in place.


The webs are gone on the trailing, but are in place on the 

 > leading plug in this RX8 pic.

Royce

It is amazing that there have been so few changes over the years.

Paul Lamar
 
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