ET77 Mainshaft Oil Scroll

[rapcom]

Gentlemen,
May I have your expert opinions as to how close a fit should be the ET77 Mainshaft Oil Scroll (called Main Bearing Distance Piece in the Parts List) in the ET19 Main Bearing Spacer ?
I have two used ones available, one 1.3580", the other 1.3585", but both are slightly sloppy in the ET19. Given that ET77 plays a part in oil control, should the fit be as close as possible but still allowing free rotation, or will a used one suffice? How quickly will a new one wear down to the same dimension as the ones I have already?
Would too good a fit reduce the oil supply to the outer main bearing to ill effect?
Does anyone have a new one handy that they could measure?
Many thanks.
Rapcom

 

[clevtrev]

Make the fit as close as you can, bearing in mind you have to assemble it. If the ET19 is a good fit in the case, then what happens is, that the hole will get smaller as everything expands the scroll will then be tight in the ET19, and will eventually wear until it is a running fit.

 

[roy the mechanic]

I have no idea about the vincent , the Daimler v8's have a near identical oil scroll in the crankshaft to front cover "seal". When aligning the cover for assembly 3x .010" feeler guages at regular intervals are used to centralise the cover to scroll. These do not leak until the crank case pressures rise due to bore wear. Consequently, as long as the scroll is cleaned before assembly, and rotates (it has a left-hand thread to draw the oil back) I can't see a problem.

 

[craig]

When fitting a ET236 main shaft seal, which only allows engine oil to lubricate, what is modified with ET77/ET19?

 

[Big Sid]

On the alloy separator disc between the left mains . It was of easily wearing away material to sacrifice itself easily . It ran quite close to the reverse scroll yet spun freely when bedded in . No need to go for a super close fit , just follow the logic . Oil gets past it to the big ball race in all motors this advice being followed . Sid .

 

[clevtrev]

On the alloy separator disc between the left mains . It was of easily wearing away material to sacrifice itself easily . It ran quite close to the reverse scroll yet spun freely when bedded in . No need to go for a super close fit , just follow the logic . Oil gets past it to the big ball race in all motors this advice being followed . Sid .

With the mainshaft running between two bearings, The scroll on the shaft, and the alloy sleeve in the bore, the only possible way the parts will touch, is by one or both being eccentric.
Steel will wear before alloy, as in rocker pins and cam in head motors.

 

[riptragle1953]

The softer alloys absorb grit.