To lap or not to lap my housings??
 

I am looking at building a spare engine for my car. The intermediate housings are not out of spec but there is wear in the in the normal football shape on them. I am installing new mazda seals and housings so I was wondering if this is a good idea.

I have heard some people say not to and some say that this should be done. I also have mean told that you need to change the letter on the trust space when you lap. Is this true as well? It does make sence.

I did search but could not find a thread on htis

Thanks for the responces,
Chris

Not lapping is like rebuilding a boinger without honing the cylinder walls.
It is neede for maximum compression. If you do not care about having a more efficient engine, no problem, also reuse all of your seals even if in spec.

The boinger people normally do not reuse seals when rebuilding. Why rotory people, because our parts cost more.

Lapping does not affect thrust since the surfaces that affect thrust are not envolved. You need to study the manual.

I stopped building these engines because the shipping was to high to send the irons to be lapped .Last week I found a shop that is going to grind one for me to check .If they can do the job then I will build a few engines ,I have 14 irons to be done ,I should see the test part this Monday . Restetting the end play by changing the sleeve or grinding one is not a problem .

If the wear falls into Mazda specs then use them. But if the car is near the wear max or the car is going to be run hard or is a high HP engine replace the plates. When you lap the housing you are removing the nitriting and you will get more rapid housing wear.