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Milling down 13b rotor housings

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Old 06-21-20, 12:39 PM
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Milling down 13b rotor housings

Just had some questions on rotor housings, the ones that came out of my 12a that I'm trying to rebuild are not looking too good and have chrome flaking on a few spots:



I'm guessing it's not a good idea to use these if I want an engine that will work well, right? So since 12a housings are impossible to find I'm thinking about getting some cheap 13b housings from eBay or facebook and cutting them down to fit in the 12a since I've got access to a machine shop at work. Has anyone here done it? How hard is it to machine the coolant seal grooves with a manual mill? Also I think the 13b exhaust ports are a bit bigger, will they still work ok with 12a sized headers? Thanks.
Old 06-21-20, 07:41 PM
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That is a very good rotor housing in 2020!
Keep the revs below 8000 and make sure your apex seal slots have no more than .003" clearance and run 'em.
Old 06-21-20, 08:56 PM
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Yep chip motor sport has video of him doing it . Most shop are doing it since 12a are getting harder to find
Old 06-22-20, 09:45 PM
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UT

Just checked and looks like my apex seal slots are within spec so I guess I'll just give these housings a try. Might as well build this engine up for super cheap since it's my first one and save up for a 13b or V8 swap later. Thanks for the help.
Old 06-22-20, 11:35 PM
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.........................................v8....... .....................
Old 06-23-20, 10:23 AM
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Lol, definitely want to LS swap it and then show everyone on this forum for max cool guy points.
Old 06-23-20, 11:25 AM
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Originally Posted by 907RotaryFB
Lol, definitely want to LS swap it and then show everyone on this forum for max cool guy points.
perfect... stay in alaska
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