Reusable rotor housings?
08-22-21, 08:39 AM
#2
RX-7 Bad Ass
iTrader: (55)
I don't see anything crazy on them, but pictures are a little small.
In general, things that will rule out a rotor housing from use -
- gouges in combustion chamber surface from a broken apex seal
- chipping/flaking chrome
- badly pitted coolant passages or pitted area the coolant seal touches
Remember too there is usable and there is "perfect". You can gain more compression on a motor with better (or new) housings but in many cases you don't gain enough to make it worth the cost. My RX-8 had fairly worn housings when I rebuilt it but it is making compression numbers in the 8's now due to new apex seals and carefully clearanced side seals. Starts perfectly every time and makes great power.
Is there a particular spot that you are worried about?
Just think about it. If there's a spot where the surface is uneven that can mean gasses can blow by the apex seal there and it can also wear the apex seal faster. If it's smooth you're OK.
Dale
In general, things that will rule out a rotor housing from use -
- gouges in combustion chamber surface from a broken apex seal
- chipping/flaking chrome
- badly pitted coolant passages or pitted area the coolant seal touches
Remember too there is usable and there is "perfect". You can gain more compression on a motor with better (or new) housings but in many cases you don't gain enough to make it worth the cost. My RX-8 had fairly worn housings when I rebuilt it but it is making compression numbers in the 8's now due to new apex seals and carefully clearanced side seals. Starts perfectly every time and makes great power.
Is there a particular spot that you are worried about?
Just think about it. If there's a spot where the surface is uneven that can mean gasses can blow by the apex seal there and it can also wear the apex seal faster. If it's smooth you're OK.
Dale
08-22-21, 05:08 PM
#3
Racing Rotary Since 1983
iTrader: (6)
as Dale indicated, it is a bit difficult to make a decision based on a few pictures however they look pretty good.
your surfaces look pretty good although you have some chatter. all housings develop chatter marks.
as the apex seal travels over the spark plug boss it is pushed into the rotor due to the plug area being hotter and rising off the surface. ( spark plug mountain ). the apex seal springs back and then you get the back and forth as represented by the lateral succession of lines especially near the top of the housing.
i recommend all used housings be properly honed prior to re-installation. relatively inexpensive and if done correctly you have almost like new housings. as usual, you have to be very selective as to who is going to do the procedure. RotaryEngine.com is at the top of my list. while they are in Canada, it isn't a big deal as to shipping, especially if you use FedEx and let them fill out the forms. as part of the service your housings are soda blasted which cleans all the calcium carbonate from the water passages.
seldom mentioned re rotor housings is the first thing i do re evaluation... measuring their deviation from parallel. the factory service manual states that if the housings are .0024, or more, from parallel in the four key areas they should be discarded. this is not uncommon and is the first item of evaluation on my 6 page spec sheet. if the housings have shrunk due to being overheated they will tend to lose the coolant seals. i found one NEW rotor housing to be at .0019 and returned it for another. RE measures them prior to honing. out of spec rotor housings are not uncommon.
good luck.
your surfaces look pretty good although you have some chatter. all housings develop chatter marks.
as the apex seal travels over the spark plug boss it is pushed into the rotor due to the plug area being hotter and rising off the surface. ( spark plug mountain ). the apex seal springs back and then you get the back and forth as represented by the lateral succession of lines especially near the top of the housing.
i recommend all used housings be properly honed prior to re-installation. relatively inexpensive and if done correctly you have almost like new housings. as usual, you have to be very selective as to who is going to do the procedure. RotaryEngine.com is at the top of my list. while they are in Canada, it isn't a big deal as to shipping, especially if you use FedEx and let them fill out the forms. as part of the service your housings are soda blasted which cleans all the calcium carbonate from the water passages.
seldom mentioned re rotor housings is the first thing i do re evaluation... measuring their deviation from parallel. the factory service manual states that if the housings are .0024, or more, from parallel in the four key areas they should be discarded. this is not uncommon and is the first item of evaluation on my 6 page spec sheet. if the housings have shrunk due to being overheated they will tend to lose the coolant seals. i found one NEW rotor housing to be at .0019 and returned it for another. RE measures them prior to honing. out of spec rotor housings are not uncommon.
good luck.
