i know when you machene irons it removes the tough nitration. but there are some rotary shops who will machene them if there worn out of spec.
but ive heard some other rotary shops say to never machene an iron.

 

this is a very debated subject, i know alot of peeps who have machined and had no problems

 

The racing beat tech man says you can remove the nitriding as long as you use their lapping process. Ibelieve they can be surface ground by someone who knows what their doing. I'd heed their warning about making the o-ring grooves to shallow (remove no more than .002" per side. Heat treating companies can re-nitride the side housings.

 

does any one have a motor with machened irons? if so how many miles? turbo or na?

 

most rotary builders can and will lap irons but they must be within a certain tolerance for wear, the nitrite layer is only so thick so lapping them too far will take off the treating. i'm sure they could be retreated but i don't think it is cost effective at that point.

 

Depends on who you know. Any body looking to do this needs to know there are a few different grinding processes and nitriding processes out there. First, there is "Blanchard Grinding". The corsesed, bad? It what they used factory. Then comes surface grinding, and then lapping. There are two types of nitriding that I am aware of. The first being "Nitrowear", the other being "24 hour gas nitriding". "Nitrowear" go's only .0002"-.0005", "24 hour gas" go's up to .030" deep. The .002" deep factory nitriding may not be avaiable.

 

It's a lot easier to find good, used irons than to go lapping them.
Lapping cuts down on the width.
To compensate, you need to get an appropriate width spacer to compensate.
There's like 5 different sizes, and if you need to go from thinest to thickest, it's still a 0.02mm difference between sizes, which gives you a 0.08mm maximum.

0.08mm is NOT that much room to play with.
That's slightly over 0.003" if I did the math right...

If you're knocking 0.002" *per side*, that's already x4, which is close to triple the max the spacer can handle (on best case scenario!).

I'm one of those against lapping.
They induce more problems than it fixes.


-Ted

 

I'm very curious about the afore mentioned spacers. Are you talking about spacing the front thrust bearing to make-up for lost material? .002"x6 is .012". If you shim the thrust bearing half that, the crank sticks out .006" f&r. I was told .012" out the back would not be a problem. I'm at half that and was not planning on shimming the thrust bearing. Do I need to worry?

 

I am another not in favor of lapping irons. Even a moderate amount of step wear on an iron does not really affect compression adversely enough to make a difference. Even if you have a badly worn iron, used ones are easy to get, so why bother? Worry about the rotorhousings more than the irons as far as sealing.

I've heard of people having coolant sealing issues, side/corner seal wear issues, and even (after the lapped iron wears out quickly) smoking issues from lapped irons because they tend to wear even faster after the process in most cases.

I haven't seen anyone who can make a case that irons being lapped is necessary for a good engine, and worthwhile when the risks are weighed.

 

I re-nitrided the irons. Thought you might like to know.

 

thank god i don't have them lapped.

 

I have to admit, this was a cheap and easy thing for me. I won't bore you details but I did it through work. My question now is will this stack-up difference be a problem?