We consider there to be four “types” of rotor housings:
1) New – require only quick inspection to be sure there was no bad casting or shipping damage and they are ready for assembly or porting.
2) Used in EXCELLENT Condition – very rare to find, require lots of cleaning and inspection.
3) Used, not sure if they are good or bad – these are the most common and require lots of cleaning and a DETAILED inspection before using.
4) Really trashed used ones – very common and require no cleaning and almost no inspection – should go direct to scrap pile.
Benefits of NEW – Very little time spent, virtually no question they will work great, least amount of break-in time, will outlast any of the others, will make more power than used housings (better sealing), etc. etc. The ONLY drawback is the cost.
This page is to help a little with categories two and three — deciding if those used ones are acceptable.
We could include literally hundreds of pictures, but they would mostly be variations of the key pictures shown below.
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The chrome flaking, as above, is the hardest judgment call for the home engine builder. There is no “solid” rule for when to discard the housing – it becomes YOUR choice. Minor flaking (less than 1/8″ wide, for maybe 2-3″ total length around the housing) can usually be used with good success. Flaking in the 1/4″ range becomes highly questionable – you need to really think about what you want out of the engine. | |
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The bottom line is: if you are using used rotor housings – check them VERY close! This page does not even include the factory manual thickness measuring check. We do that AFTER we have done the visual inspection. It is rare to find one that will pass the visual, and then fail the thickness test (but NOT unheard of – so also measure them). We know new housings are very expensive, but we also can always tell the power difference between a “new housing” engine versus a “used housing” one on our test drives after installation. |