The camshaft is here. I took the afternoon off to get some things done on the car, but before I go back to work on the engine, I’m waiting for Fordboy to get back from Tejas. FB, if you’re checking in, both the clutch slave and the spec sheet from Elgin should be in your mailbox on Saturday.
Here’s the deal, and again, it all has to do with oiling –
The camshaft has three bearings, and drives the oil pump off of the back. The rear bearing is always lubed by oil sloughed off of the pump.
When Zinc was removed from standard motor oil, many folks in the British car community started encountering lobe wear issues, distributor drive gear wear and hammered lifters. The suppliers of high performance cams, such as APT, who supplied the blank that Dema ground for me, countered the problem by drilling oil holes on the lobe bases, something the stock cams never had. Additionally, three holes were drilled on the distributor drive gear.
Did I mention that I’m not running a distributor?
That’s 11 new places to lose oil pressure.
So where does all this extra oil come from?
2 MORE holes drilled into the cam on the front and center cam bearings to collect oil from the cam bearing circuit.
Okay, that should save the lobes – that was the issue, although with all the oil splashing around in the crankcase, it seems to me to be overkill. But if we trace the circuits back, we find that now were feeding this cam off of both the front AND the center main bearing galleries.
Keep in mind, I’ve only got three.
The front main bearing is located by a very solid cap and is very stable. Oil from this bearing feeds the front cam bearing. But the center main bearing feeds throws 2 AND 3 on the crank rod bearings, the center main itself (always the weak link in the A-Block), with salvage going to the thrust bearings. I feel queasy about asking it to help service a device not unlike a decorative water sprinkler spinning at 4000 rpm.
In short, I need to keep the center main bearing and the associated rod bearings wet. Drawing off oil from this point is ludicrous.
And I'm not sure I need to feed the inside of the cam at all, provided I use a high Zinc oil.
When Fordboy gets back, we’ll discuss the physical procedure as to turning off the sprinkler.