ET: Engine (Twin) Any Drawbacks To Crankcase Polishing Internally?

[Whiteshadow15]

I know some say it’s a fine idea to help with oil return although not necessary.

I have some times on my hands with a set of chopped cases but was curious if there is anything to be concerned with.

 

[passenger0_0]

I would have thought the main bearing stiffening webs would cause greater aerodynamic drag and resistance to oil return than the crankcase casting surface finish. Best not to remove these though. Maybe more productive to put your spare time into external cosmetic polishing and just tell everyone it's the same on the inside.

 

[Whiteshadow15]

Yeah I figured I would just clean up the webbing but leave it. I have time so I think I might knock it outside for fun. I’ve wrapped up the outside of the cases, it’s a multiple year project so time is not an issue at the moment.

 

[highbury731]

I have seen car engines, particularly for racing, with the crank case interior painted with a special brown paint. Allegedly it aids oil drainage. I have no idea what the paint is, or if it works as described

 

[chankly bore]

The idea that internal polishing will aid oil return is a Furphy (look it up), since a standard pump only has a stroke of 1/4" and runs at 1/15th of crank speed. Remember, this was good enough for Tony Rose! Even a double start pump is only twice as fast. That, surely, is what limits oil return; or have I got something wrong again? I believe the MiTy Garage Rapide had that internal brown coating. I reckon you're better off spending your time riding the trinket while you still can.

 

[greg brillus]

More for stress relief..........oil run off would be a near waste of time, the windage in the lower cases is a problem for these engines that no one ever considers........well if your into gaining more horse power that is.

 

[Whiteshadow15]

I’d rather not mention how many hours that’s been. Still a bit to go.

 

[Bill Thomas]

I think Ted Davis of the Works Factory ,
Said they did it to a Grey Flash ?.

 

[Chris Launders]

To my mind it should result in a cleaner running engine, there's nowhere for any bits of carbon etc to stick, and it'll be easier to clean any debris out if it goes bang.

 

[vibrac]

Someone with time to spare in the workshop!