sbrmechanic

Alright all you engine builders, what is the exceptable amount of chrome flaking from the outer edges of a rotor housing, my housings mic out ok but i noticed a little score around the very edges of the housings ill try to get some pictures, any input would be great!

RotaryEvolution

iTrader: (30)

ideally there should be no substantial step or peeling in the upper half of the housing from the oil injection port to the lower spark plug, the lower half can in fact be rather shotty looking and still perform ok. BUT steps in the bottom half will wear the seals to want to dig into the housing around the whole circumference.

normally i would scrap a housing if the wear is more than 2mm wide around the whole housing and deep enough to really feel when running your finger over it. chrome peeling in the upper area larger than a 3mm/3mm spot of the housing to the steel liner immediately disqualifies the housing IMO.

if there is no peeling to the steel liner at all and just a step from the boot the housings can be resurfaced for better results.

the OEM small boot design is a bad one by defualt, the small surface area of the boot turns it into a metal awl on the housings. most aftermarket seals use a wider boot for more surface area and less digging into the housing. the smaller boot does cause less inconsistencies with compression leakage though.

sbrmechanic

thank you that was very helpful, is it the kind of thing where you put the motor together and it wouldn't make it more than 200 miles or more like 20,000?

this Nissan sounds funny

Putting a motor together is an investment of time and money. Why would you waste that on a sketchy housing?

RotaryEvolution

iTrader: (30)

if a housing is used that fails my criteria it would just result in more compression loss than average with used parts. a housing with an excessive step or moderate to large amounts of wear in the upper region would likely result in very poor initial compression and even when broken in probably still near or below failing numbers of 85 and below psi.

i resurface the housings so even step wear around the edges is either removed or nearly completely removed so the seals have a true surface to break into giving engines 100+ numbers once broken in rather easily.

engines built with excessively worn parts are often the ones you hear about that flood easily on startup and take thousands of miles to even become somewhat easy to start without assistance. in most cases even a 100k+ mile housing can be resurfaced and have none of those issues.

if your housings are either at or below those specs you can either ask a shop about resurfacing them or put that money towards housings that are in better condition. if you opt to build it with worn out parts then the money invested into the rebuild might be in vain and the results less than ideal.