Camshaft bush oil way bore size.

[Colin Wilks]

I am reworking the camshaft fixing bolt on my bog standard splash fed '33 RP.
The standard oil way drilling in the bush is 3/16" (assuming mine is a standard item). I have been advised that 1/32" is a better size for this oil way, which seems mighty small to me.
Interested to know other's custom and practice before I start drilling. I plan to have a standard assembly, so will not be embedding o rings fore and aft. End float will be approx .001".

[Chris KC]

Colin, you can certainly take this down to 3/32" without much fear. I suggest one thing to consider is whether you run an in-line oil filter or not; if there are larger particles floating around you run the risk of blocking a smaller orifice.

1 thou end float sounds a wee bit tight to me - I think the companion suggests 0.002-0.004".

[Ian Williams]

Agreed, 3/32 and don't run less that .002" cold or the cam will seize in the bush as the engine warms up, i suggest that you restrict the rear cam bush as well.

[Colin Wilks]

Thanks for that gentlemen. Woodrow quotes .002" endfloat, so that will teach me to work from memory!

[dickie65]

Hi,
The smaller orifice is used on full pressure engines running at around 60 PSI oil pressure, this is to restrict the oil loss via the camshaft bush and to direct more oil to the Big Ends.

[Bob Culver]

On low pressure engines the trench to front of bearing and groove in timing gear must be retained as oil feed for the gears. To cure the considerable leakgae around the oil hole I used to just build up the bush exterior in vicinity with solder .