nearly have my engine built to start up and someone suggested to check the oil pressure valve and bypass valve mating surface within the engine case as they had a problem with theirs and it was letting oil past to easily and reduced engine oil pressure.
I have a new CB aluminum case and am a little worried. If you look inside the case at the area where the piston/valve is meant to seat, there is a small outer ridge (see photo) and this is stopping the two flat surfaces coming flush together as I think they are meant to.
Can I just increase the bevel on the piston slightly so the two surfaces will meet flush.
If the plunger was to seat tightly against the end of the bore, how would oil pressure ever be exerted against the top of the piston to push it down?
There's rarely any call for a slotted plunger (or the stiffer spring that comes in the "high-pressure" kit in which it comes) in a dual-relief case. Both items have virtually no effect on hot oil pressure, they merely delay warmup of the oil.
I more than suspect that how your oil pump fits in the block has ~infinitely more effect on hot idle oil pressure.
Addendum to Newtons first law:
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
Marc wrote:
If the plunger was to seat tightly against the end of the bore, how would oil pressure ever be exerted against the top of the piston to push it down?
Marc,
I would say the answer to your question is the big hole at the head of the piston where the oil is pumped into that gallery. See it down the bottom there in my first photo
The oil pressure doesn't come from the holes on the side within that plunger area. Maybe have a look at this post and you will get a better idea of the oil flow path.
By looking at the above link, I have also realised that the piston doesn't really have to sit flush against its matting surface as I originally thought. I think it is ok even when the oil is hot to have some pass into this gallery and the majority into the oil cooler.
Looking at the pic I thought that the aftermarket case was different, but never mind
Regardless, there's no need for a seal at the top, it's just a step to limit travel. It's true that a worn bore can cause a loss of pressure at hot-idle (that may be what your friend was alluding to) but as Piledriver said, the fit of the pump is more often the culprit. Even with a totally worn-out bore, the maximum amount of oil that can pass is determined by the size of the little hole near the bottom of the bore that vents to the sump.
Tidbit:
If anyone does opt for a Giant Oil Pump to preemptively "fix" the oil pressure issues. that little to-sump passage needs drilled out to ~10mm or better, or you may have excess pressure issues, like blown off oil filters, oil coolers etc, as if the return is not big enough to deal with the flow, the pressure relief... can't.
One lister here had an aftermarket aluminum case that barely had a return hole at all.
At pretty much anything much off idle ~90% of the pumped volume goes right back to the sump, not through the bearings... That's with a STOCK pump.
Consider fixing the problem.
Addendum to Newtons first law:
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
Cool. How does it fit in the case when case is torqued up?
Hint: Must not slide in.
Addendum to Newtons first law:
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
Oil pump tang to cam clearance? (1mm+, never want the oil pump to become the cam thrust bearing)
Consider a steel or iron pump cover.
Jake Raby used to sell a tool steel pump wear plate to allow the bling covers to be just that...
The cast steel external output cover empi sells works just fine as well, although you should check it for flatness.
Addendum to Newtons first law:
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
