Lynn,

Having looked at that wear area on the end housings, I was wondering if this was in excess, could we have the surface ground and then re-Nitrided?

The whole process wouldn't be anywhere near as expensive as new housings

George (down under)

Nitride is between .003" and .007" thick or, more accurately, deep. So you could surface grind until the wear mark is within the .006" and then DA the surface to kill off the grinder marks and supply an oil holding  surface, or, grind until the wear mark is gone and then DA for a nice finish. The engine don't seem to care about it until wear exceeds .006".

 

For all out racing and to save some very expensive ported irons, Paul yaw grinds first and then laps to get his finish. Both acceptable. His is better but pricey.

 

In olden times, the irons were not Nitrided and ran along just fine. After about 100,000 miles, hard starting from low compression would set in from iron surface wear and apex seal wear. The chrome would also wear out about then even with soft carbon seals and the engine would be just about junk. I would grind the irons up to three times, and finish with a DA. I had to shim up the front stationary gear and cut a chamfer in the front end of the rear stationary gear bearing. As the engine gets shorter, the crank moves to the rear and the radius on the rear throw would run into the main bearing. I had no money and was always racing junk engines.  

 

Re-Nitride if you have to go over .006 to get a finish. 

 

Here are some measurements from Mazda but nothing on the irons.

 

Lynn E. Hanover