Dear Jag-lovers,
I’ve rebuild several XK engines and right now i’m in the proces of an 4.2 E-type engine. When I inspected the inlet camshaft my eye felt on the cam lobes which were plugged. See photo’s attached.
I might be confused, but there shouldn’t be a plug on the cam lobe, right? I thought that I am the first who opened the engine, but one of the previous owners might have done this? Or is this original?
Thanks,
Bram
This one is on e-bay , looks like there should be a hole , I bet crap has built up over the years and blocked them !
I honestly can’t imagine anyone being so daft. It’s a recipe for cooked cam lobes and chewed up followers. Given the way the rear of that one lobe is chewed up, it’s apparent that it was running with no clearance so maybe the Gomer that set up the valves also plugged them.
It could be a natural accumulation but of what? It looks like a hardening putty. Were they putting clay in with their oil? In any event, clean them out.
A lot of gasket sealers are red , if they used too much could have worked it’s way around the oil ways !
To be clear, all six cam lobes on the intake are plugged. It’s seems to be a hard plastic.
Exhaust cam is just normal with six open oil holes.
It looks like Bondo to me. While there might be a remote possibility of it being migrated pookie, it seems incredibly unlikely. The only possible excuse I can think of is that it was a foolhardy attemp on the part of a PO to stop leaking cam cover. Gee, if I can’t stop it leaking I’ll just stop it from entering.. If true, be glad they didn’t decide to just drain out all the oil instead.
I’d second gasket material IF both cams had been plugged but only one seems suspect. And I would have thought the cam feed line would be the first to get plugged.
Strange.
The oil holes were later (?) deleted by Jaguar. If it feels like plastic, even stranger. Why should only these six holes be blocked? Especially those that see less heat and more flow than most other oil passages. Must be intentional. Those cams don’t look good anyways.
David
I have no idea why anyone would attempt to do this, but I will note that not all camshafts had drilled lobes, so they may have trying to emulate a different part number.
Just confirming Mike, no holes in the valve lobes on C.2444 early XK120 cam, just at the bearings.
None on 140, either.
Holes on lobes are optional. Makes no major difference to lubrication. Jaguar switched to and fro more than once for reasons of engine noise refinement IIRC. Oil pumps changed, pipes changed, cam take-off changed. Therefore it works together as a system and the later engines with highest feed (spin-on filter and hi-pressure take-off) deleted the lobe drillings.
The PO probably blocked the the love holes to try and boost cam bearing feed. Cams look fine as long as the dark stripe at the journal feed are just discolored, not wear ridges. There is no contact over the cam heel, so any Bondo smears would not be rubbed down to metal. Best to clean out bore of cam with a rifle brush but if the love hole material looks secure it would not be stupid to leave it. Lazy maybe, but if it hasn’t moved yet it probably won’t in future.
With all them holes would the oil pressure not have suffered a little ?
No. Very little oil goes up top. On later engines the supply line comes from the left side of the rear main, the opposite side of the block from the main oil galley, The oil supply has to traverse the groove in the rear main bearing to even get up there. The tappets live flooded in an oil bath (so long as no one “improved” the return holes at the ends of the head) so the oiling from the holes in heels of the cam lobes is redundant for lubrication purposes. I think the heel drilling was more an attempt to reduce tappet noise.
I’ve decided to leave the cam lobes plugged. As @PeterCrespin and @Mike_S said het tappets are in quite an oily environment.
Beside that, i’ve tried to hammer the plugs out, which was not possible without drilling them out. It seems that they are brass or something similar. So this also indicates that this was done professionally, probably by Jaguar.
Just verify none of those plugs protrude into the main oil passage that runs the length of the cam.
Exactly. The cam bearings are fed from the rear. If one of those plugs protrudes into the oil galley drilled down the middle of the cam, you could lose oil flow to one or more of the bearing journals. For what a standard, used cam costs, if it were my engine, I would not hesitate to replace the pair.
Not really. The cam is bored to about 1/4" and the lobe holes are about 1/16" (guessing, as I am away from my engines). Either way, the 2x1/4" bore cams are far bigger cross sectional area than the feed pipe and if any bondo did exit inside the cam bore it would be as good as impossible for it to block one of the three journal feeds further along the cam. I don’t know about the very early engines but from about 69 onwards the early cam feed from the left side of the rear main was replaced with the full-pressure oil gallery feed take from the oil filter block. I think an earlier post said the opposite.
