Any one know if Jaguar drilled the back of the inlet cam shaft , and tapped a thread in it , or just left it solid , or did they plug the hole ?
1975 XJ6 3.4
Looks to me like they may have plugged the hole , not 100% sure thou !
FWIW, I have several 4.2 cams from the mid-seventies and they have no threads in the rear of them…just plugs, front and rear, to prevent oil pressure loss, though I did thread a pair of them so I could attach the oil slinger and mechanical tach-drive from my 3.4 engine just in case I chose to use the 4.2 cams on my 140…a 3/8", fine thread tap worked.
Thanks Lee , I have some 240 cams , they both have threads , when you say plugs , do you mean Jaguar filled the holes with a different metal ?
Guess they would have to as the cams are tubes ,
My plan is to drop a XJ6 Engine in a MK2 , so a tacho drive would be nice !
3.4 XJ6 cams had aluminium plugs driven into cam oil feed drilling at both ends.
Earlier XK engines had various attachments to the back of cams.The front end of the drilling wasn’t blanked off! It just relied on the cam adjuster plate face sitting up to the hole.
Thanks Nigel
So its easy to drill the plug out , is it easy to tap a thread in it , cam shafts must be toughened steel right , so would need a good quality tap !
I don’t remember any particular problem threading my cams with a quality tap once I pulled the plugs out with a slide hammer(body work device).
Camshafts are chilled cast iron. Hard rather than tough.
As far as I can remember I think they were simply a press fit. Regarding tapping a thread, shouldn’t be a problem. The cams are not hard right through, simply the outer surfaces. Just to be in the safe side I’d use a first, second and then plug tap.
Just took a few hours to do all the work , just need some new locking tabs so I can refit the camshaft
I did the drive to the head first , then decided to do the cam !
I knocked out the other plug , so I can put it back after cleaning inside the shaft out !
Well went to refit the camshaft today , and come across a problem , I have 2 different drives , but only one kind of Generator , have found a drive to fit the Generator , but the centre is worn , so will have to get a replacement !
If you’re fitting the mechanical drive spindle get a new lip seal for the bearing cap as well. They go brittle and judging by the photo it will be worn too. They’re a swine to remove, but will mean no oil seepage from this area when fitted together with a new drive spindle.Be very gentle when pressing new lip seal into cap making sure you fit it the right way round… imagine it’s a front crank seal fits identically.
I think the seal is just a 0 ring !
The O ring provides the seal between cam cover and the sealing hoisin. The mechanical rev counter versions have a lip seal around the drive spindle
O I see , I guess I have the drive for both , well I do not have a Mechanical rev counter , just the generator kind !
Just out of interest , what car was fitted with the mechanical rev counter ?
Early ones - XK and MkVII-MkVII.
MkIX had the 3.8 with electric tach gen.
The earliest cable drive tachs went anti-clock same as cam seen from drivers seat. Later they put an extra cog in the tach to reverse the needle sweep.
Just FYI, you could just skip this whole exercise and have the electric tach modified to trigger from the ignition pulses.
And you know just the guy! 
Could do , but I am a Enthusiast , nothing better then doing things my self , only job I did not do on my car was put the screens in , more of a achievement then saying tom dick and harry did that !
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