I'm ready to prep my S5 NA plates to put my keg back together. I have been given and come across certain advice. That I would like confirmed before I proceed.

supposedly this process of hand plate to plate lapping with compound/s is a must for having a succesful rebuild.

I was told to use 180-220 grit to cut. Then 400-600-800 fine grit to refine and polish. Once that's done. And cleaned. It's time to reassemble.

any feedback appreciated.

 

If they aren't deeply scored from the side seals, I wouldn't worry. As long as the area that the oil rings cross doesn't have a step, you'll be fine.

If the side seal "delta" next to/under the spark plugs is deep enough to worry about, you'll be lapping for a very long time. If it's deep enough to be concerned about, you'll have to go all the way through the nitriding to make it smooth again.

As an opinion based entirely on gut feeling, I wouldnt use '86 up rotors on un-nitrided side housings. The pre nitride side housings wore with the 1mm side seals, the .8mm (.7mm?) seals would probably chew them up quickly.

I tried lapping side housings myself once, by hand.... mostly I got very tired and didnt even scratch the nitriding. The DIY method looks like chucking them in a lathe and using a tool post grinder to cut through the nitride layer before lapping by hand.