On the rear cylinder the head to barrel union has a bush and O ring to stop leakage from the oil way. But on the barrel to casing(s) union there is neither although the casing hole has a farty (non centered sic) countersink 'machined' in. And from what I can remember the barrel, at the moment it's out at the engineers getting a rebore, also has a badly machined recess that doesn't look like it could hold an O ring. All the parts diagrams etc don't show anything at this point either so is it just up to the base gasket to prevent any leakage from here?
Just checked a set of cases and someone has chamfered your drain holes for whatever reason but shouldn't be a problem.
I'd asked because I've fitted a high flow oil pump & was seeing not a leak as such, but a little oil 'sweating' at the base gasket so was wondering whether the oil flow to the head was too much for just a gasket. It's interesting that the chamfer is non standard almost as if someone has done this to specifically include an O ring...
I never recommend high flow pumps unless you have external drains. The problem is the return is gravity fed and the horizontal pot tends to build up its oil level in the head and this can cause the front pot to smoke as valve seals cant always cope, Don't fit an o-ring without a sleeve as there is nothing to stop it collapsing in and blocking the return.
Paddy, Even though I have some AV&V valve guide seals to use I must admit I'm coming round to thinking the same re the oil pump - I have the original which is still serviceable albeit with a couple of scratches & bruises. Nothing too serious mind. Good shout on the O ring though (btw it's the feed to the head and not the return that has the chamfer.)
spot on, my mistake its the feed. ( but wouldn't be chamfered normally even so) I am not recommending it but i do know of an engine builder that used to fit a restrictor to the small dowel in the barrel/head to limit oil flow to the front when using a high flow pump. you really want the extra flow to the crank, not to the valves.
That was my primary driver for using a high flow pump but I've also had teething issues with sealing the plug on the clutch cover that threads directly over the galleries that feed the crank. Shame really because it was a beautifully made piece of kit - perhaps I could sell it on here Hey ho we live and learn.... sometimes.
You could always run a drain from the front bottom valve cover back to the sump via the oil filler if you were concerned about the front head filling with oil . Or put restrictions in the feed to the heads
And strangely enough I've also had a gentle weep from the rear bevel drive tube bottom seal so perhaps the pump is just too much flow for the old gal. Yeah I've seen both of these been done before and is a possibility when my mechanical acumen is up to the task and (retirement) time available So perhaps the new pump can remain on the shelf a little while longer. Although the external pipe work solutions don't always look the best.
