I'm about to repair my side and intermediate housing, which with minor scratches. How much actually can these housings can be machined down? Or, can I cut the scratched area deeper then weld it and then do a flattening job?

 

Housing coatings are pretty sensitive and cannot be easily repaired. The most practical thing to do is to replace them 99% of the times.
How are their tolerances?
Lapping the side plates is doable but keep in mind that if you have to remove too much material the surface will be softer. Ok for a purpose built engine that will need to be rebuilt soon anyway but i wouldn't do it if durability was a concern.

 

Means that is better to buy a complete new engine?

 

It means that you should check if the parts are withing factory specs first and then make your move!
Usually getting a reman engine while sending yours back is fairly more practical\economical\safe than rebuilding your own with the right amount of new parts!

 

My plan is fix whatever can be fixed then send to a rotary engine builder for rebuild. If I can fix the side and intermediate housing, then it is worth for a rebuild.

 

the only thing that you can "sand" is the nitrated coating. the coating is about 0.02" inches thick.

most people can't do it themselves, cuz it has to be perfectly even.

there is a way that you can sand it yourself, but its an ultra painful process which I won't even bother to do them.

Best is to buy new housing, or see if you can find a known- used good housing (or engine)

 

I'm not gonna sand it by my hand :D I'll send it to a machine shop. Maybe I'll ask them if hard facing will do, or, they have any suggestion. But looks like I have to buy a complete engine.

 

Send it to somebody that knows what they're doing and keep your amateur self from making fubar decisions, including listening to most of the replies here

Why you want to handle thus yourself in the first place and then send it to the builder clearly shows your tripping over your own feet in left field right out of the gate.

Nothing personal mind you ....

 

send it to builder will end up with buying new housing. Most shop in my place is focusing on turn around time, which means they can finish a job in the shortest time and get the customer pay as fast as possible. It is not worth for them to charge a small handling fee but wasting their place and time. Honestly, I can't even find someone who are willing to do a port polishing job. If want port and polish, send to Japan. What can you expect when they look at a scratch housing? So I have to figure some way out myself and this forum is a good place to start with besides google. BTW, everyone start from amateur. The contribution of those experienced people in this forum will bring up amateur to become someone and this is one of the reason for the existence of a forum.

Basically, repairing the housing may not worth it at the end. But What I'm after is the passion, not my money. Who knows it will end up with a housing with TiC or WC face.

 

I'm sure there are rotary specific shops that would port the housing for you, but there aren't the gains found in the older rotaries. If you're the sort of person who needs/wants someone else to rebuild your engine, I think it's probably best that you not start doing porting, applying wacky coatings, etc. Many, but not all people who start going down that kind of road end up requiring a lot of effort to be spent on their car. It's a probability game. Fix the car and drive it in ways that allow it to be appreciated best (eg. autoX, lapping days, etc.). Search through the forums for people doing major modifications. How many run into the same number of issues as a stock car? Not to say that it was bad, but my old TII was less hassle when it was closer to stock. I do not claim to be the most knowledgeable person on the forum, but I've been there done that.

Lapping the housings probably isn't worth it. If they're out of spec have you considered buying a used engine to use for parts or as simply a replacement? That would likely be the most cost effective and best value option. It's what I would do. Using fine grit sand paper or scotchbrite pads is perfectly acceptible in the right circumstances when rebuilding an engine.

 

like I said ....

 

repairing(more like resurfacing) a housing will always be cheaper than buying it new(assume that its resurface-able)

one thing to keep in mind is that some known good shop would not port Used housing, they will only do it on Brand new (Example : Mazdatrix) for obvious reasons.

Best thing for you to do is call around and ask, if they say ok, we will look at it, then just send your housing over, worst case scenario is you loose maybe 30-40 bux in Shipping. not a big deal.

 

fine grit/sand paper/scotchbrite pads on the housing ? ...

 

Actually you can do a decent hand lap with a ground flat ( precision) metal block and some wet/dry sandpaper....won't fix anything major...but you can smooth out the tiny stuff

 

its true but its kinda hard to find a ground flat block and you have to sand it for a long time ...

if its me I will just send it off and let someone else do it.

 

Or just get a new plate


...round and round we go,,,till someone falls off the merry-go-round

 

I believe it's part of the Bruce Turrentine rebuild video, as mentioned above, it's for minor imperfections when reusing a housing.

Just trying to support what you said. Threads like this usually only get a post or two by someone who has actually rebuilt an engine before. Again, I'm no expert, but I've done a couple and been involved in several others.

 

Everything I have read and discussed with builders say don't repair 99 % of the time.

Listen to Bag head.

 

If you lap the side housings you are will be cutting into the nitriding which is there for longevity. And I don't trust aftermarket nitriding processes.