hi everyone



i recent got a 12a 6 port and started take it apart and cleaning bits a pieces i have reached i think the engine can be rebuild however i need new rotor housing , and a rear rotor (weight B) fortunately for me in my country i have found some brand new 12a rotor housing for about $150 US well actually a bit less , and i will have to check to see if the person has any b rotors also , my major concern however is the plates and lapping them i have read allot on the forum and will be taking Lynn E Hanover advice on lapping them however there is some pitting around the water jacket area that are pretty close to where the seals will mate with the plate i have some pics below from when i initially opened the engine they are not clear but u can understand what i mean , i have cleaned the plates a bit and i will take some pics and post them next weekend before i start the resurfacing procedure here are the pics





[img] DSC00079.JPG [/img]

 

 

the brown spots in the edge of the housing is a mixture of rust and some sort of sealant some one used i have removed this with some wd40 and light sanding already , in the 3rd pic you can see there is some pitting on the inner edge of the water jacket , my question can i use devcon to just fill the pitted areas before lapping the surface ? or should i just get new plates ?

 

New plates would be ideal.



You can have these plates ground by any shop that grinds cylinder heads. Take off just enough to clear off the damage. Then lap the plates against each other with valv grinding compound to get a great oil holding surface. Even if you remove all of the nitride, the plates will go about 100,000 miles in normal use. Or, you can have the plates re-nitrided and go 200,000 miles.



Or, you can run over the plates with a Random Orbital sander. Common in body shops the air powered sanders that use round sanding discs on an air powered device. Can be found as electrics but with square pads, used in cabinet and furniture shops. Run dry 320 paper first, dead flat. Make no effort to remove more in the damaged area than anywhere else. If most of the damage is then removed, go on with 320 wet or dry silicone carbide paper weted with diesel fuel, or light oil or Kerosine lamp oil. Then lap the iron.



You need a nearly solid surface between the combustion chamber and the "O" ring mating surface. The pressure between the iron and rotor housing holds back the combustion gasses and pressure. So if you end up with that much from TDC to the exhaust port open point, you will be fine for NA use. For turbo use, get new irons. A thin film of silicone on the rotor housing will take car of most of the problem except for the high pressures of combustion.



Make a gizmo to lap one iron against the mating face of the next iron. A spiggot to fit the chuck of a milling machine or slow turning drill press. A bit of bar stock bolted or welded to the spiggot, and any old ball bearing race bolted to the bar stock. Outer diameter of the bearing race orbit, just 1/2" bigger than the oil drainback hole in the iron. (That big hole in the center of each iron)



I can make a picture if you need that.



Here is a picture of a Damaged Renesis iron that has been so lapped.



Lynn E. Hanover

 

pictures of your jig used to lap the plates against each other using a drill press would be nice i am about to take some more pics of the plates after some light sanding to actually show the pitting i am talking about i will post pics shortly

 

I BRING PICS OF PITTED PLATES



ok so here at the pics of the plates a little cleaner as i can see its pitted at the water jackets on both sides i was wondering the plates can still be used , or if i can decvon the edges and then lap the plates , i will try to get some new plates also jus in case these dont cut it

 

Here you go.



You must use a press that can turn very slowly. A big DC motor with a speed controller is good, or another set of cone pulleys on an AC unit. A plastic pan under the table will allow for recovery and re-use of the compound and help with cleanup.



Gently clamp the bottom iron to prevent movement. Keep the compound a bit runny by adding oil or water depending on the style of compound. (Water or oil based).



Lynn E. Hanover

 

LYNN thanks for the diagram , any advice on what to do with the plates based pm the pics of them i posted previously ???

once again thanks

 

LYNN thanks for the diagram , any advice on what to do with the plates based pm the pics of them i posted previously ???

once again thanks

 

It would depend on how much money is available. There were times when I would have saved those irons unless they were broken in half. Now I only use new irons when I have a choice. Some times you don't have a choice, or the owner cannot afford all new stuff and I work a bit harder at restoring a finish.



You must have both a surface for the "O" ring and the inner half of the rotor housing to seal against. You can fake the outer half with silicone or Permatex. Very important on the hot/pressure side of each surface.Not so important on the cold/suction side. Probably OK for a street engine just to drive to work, gently.



For hard use almost anything with less damage would be a better choice. Use these parts to get your lapping rig set up and running. Or, lap them for an hour or so and see how they come out.



You can try it by hand just to see what is going on, and how much effort is involved, but you may not last very long.



Lynn E. Hanover