Hi All,



I thought I'd share my recent modification to my MK2 (see attached photo). Having made various improvements to my car (4.2 engine, Xj40 XJR electric seats, Volvo brakes etc) I was always wary of the oil pressure reading from the standard electric oil pressure gauge - they're only as good as the sender unit and gauge. I purchased a Lucas/VDO capillary gauge & associated pipe/connectors from a well known Jaguar specialist BUT where do I locate it ? I didn't want to replace the original item as the appearance was different. One option was below the dash, either left or right of the steering column but I think that would look untidy & aftermarket. Having fitted radio speakers in the A posts and rear parcel shelf the original speaker above the radio was redundant so why not utilise that space. I made a plywood panel to sit behind the radio panel, secured with two of the black plastic thumbscrews which are used to secure the hinged switch panel. One gauge, I felt, would look a bit lonely so I decided to fit a Voltmeter (XJ Series 3) alongside. I had previously fitted a switch below the dash for the electric radiator fan so it made sense to put that in a more prominent position as well. Having scoured my boxes of accumulated Jaguar parts I came across a chrome heated rear window switch (push/pull) and an original lucas tell-tale light. I think they look perfect in their central position.

The 4.2 engine I fitted was originally from a Series 3 XJ6 (1984) and was equipped with an oil pressure switch on the right-hand side near the distributor (this was to illuminate a low-pressure light on dash). Obviously, without such a light this switch was redundant so what better place to use as a take-off for the new gauge. It doesn't screw straight into the oil galley but sits inside a short (25mm approx) hexagonal fitting. If fitted straight into the galley it may well interrupt the oil flow. I used the narrow plastic tube which came with the new gauge but will eventually replace that with a coppr pipe as I'm concerned that it may get damaged. My only gripe is the bezel around the Voltmeter, which differs from the oil gauge (and originals). However, it is possible to replace just the bezel, which I will do at a later date. Upon starting the engine my waryness of the original oil gauge proved correct - the new gauge went straight up to just over 4 Bars (which equates to about 60psi) whereas the old gauge steadied at around 30-35psi !!

The Voltmeter is also a useful addition - I've wired directly into the permanently live circuit (some people use Ignition Live but as there is no electrical drain I'd rather see the state of the battery when I get into the car).

I know some owners would wince at any straying away from originality but I'm a great believer in sensible modifications BUT they should be in keeping with the original design. I know my XJ40 seats are more modern but I think (as they give more support) that they could be classed as a safety upgrade (they're also electric rise/fall etc which is a nice addition !). My next project (which is well under way) is a Power Steering conversion. I've just fitted new seals to a Burman Power Steering box, amassed the correct drop links etc. Due to a lack of space on the right-hand side of engine which I think would make it difficult to fit an XJ6 pump I've decided to fit a Vauxhall Astra electric pump to the left-hand inner wing. In order to do so I've modified the Vauxhall bracket - the pump is quite heavy so I thought their substantial support was essential. I've now got to get a suitable high pressure hose made - 1/2" JIC fitting at the box end and a Vauxhll flared 16mm end on the other. I'll report back onto the forum when that all up and running (hopefully !)

Can't seem to be able to attach photo at this time so I'll add later.

 

Hi,
you've unknowingly answered some questions I have regarding replacing my 3.8 liter engine with a 1983 XJ-6 4.2 liter engine.

what Distributor did you use? the 3.8 points and condenser distributor, or the XJ-6 electronic distributor?

I was wondering what that oil sensor was under the distributor, so that one is not needed, right? (my car is a 1965 3.8 'S' type). Where do you then connect the oil pressure gauge?

What oil filter head did you use? the 3.8 is angled down or the 4.2 head which is sideways?

and where did you connect the Tachometer?
the 4.2 does not have a tachometer generator.

Thanks for your help.

 

Hello Jose,

I'll answer your questions in the order asked: With regards the dizzy, I opted to use a new old stock S2 XJ6 one with conventional points (I did try an electronic conversion but for some reason had problems setting the ignition timing). The oil 'switch' I refrred to is very similar in appearance to a water temperature sender/sensor (I would attch a photo but for some reason I can't upload at the moment). It's located in the frontmost oil gallery plug just behind the dizzy. The oil filter housing used was from a S2 XJ6 - this is unusal in that the filter (EBC9658) points upwards - I'd read somewhere that the other types could foul on the crossmember - I believe part number is C44361. Obviously with this 4.2 conversion you lose the drive for the tach (rev counter) which is normally driven from the rear of the inlet camshaft. To resolve this issue I used a 420 Jaguar tacho which takes its electrical feed from the coil - the only drawback is that you lose the timeclock which is in the MK2 tacho. I've since fitted a small removable clock (battery powered) into the right of wooden dash, where the heated rerar window switch would normally go (if fitted). Finally, if you do decide to go down this route you'll be pleased to know that the MK2 engine mounts bolt straight into the block (the threaded holes are still in the casting).
I read various comments saying that I would have problems with the cooling fan catching or being too close to the radiator - I haven't found that to be the case (I have fitted an electric fan in front of the radiator just in case the extra heat from the 4.2 engine (if there were any) is taken care of.
I'm very pleased with the way the car performs. It did take a while to arrive at suitable needles in the 2" SU HD8 carbs - it's surprising how much difference different needles make !

God luck if you decide to do the same.

 

Many thanks for your reply.
.
I was wondering about the tachometer.
Surely there must be another way around this. Going to contact Speedy Cables UK to see if they have a solution, I am sure many others have replaced their 3.8 engine with a 4.2.

I assume you are still using the original radiator and have no issues?
Thanks.

 

Hi again,

I'm sure there must be a way to convert the XJ6 engine to drive a generator - nothing's impossible and I'll bet there are references to doing so on the internet. However, knowing how unreliable the old fitted clocks were I decided to fit the 420 tacho & wire accordingly. The little battery in my aftermarket clock should last a couple of years at least (and it looks period). With regards the radiator - I had my original one re-cored but with a more efficient core and, touch wood, its been fine with the temperature staying exactly where it should. If you have any more questions I'll be glad to help. Regards Keith (I'll post some pictures when the uploads work !)

 

Hi Keith, thanks for your offer to help.

I had my clock modified by Mike Eck of Jaguar Clock .com and it has been reliable since he fixed it. It actually ticks and keeps perfect time!

So I don't want to lose the clock and certainly not the tach.

I wrote to Speedy Cables UK, waiting for a reply and I will post it here as soon as I know something.

I really want to get the 4.2 in the S type, the tach is not going to stop the conversion. There has to be a solution.

I will send you a private message with more questions if that's ok.
Again, Thank you.
Jose

 

Hello again Jose,

There are three hurdles to fitting a tacho drive to the XJ6 engine. The first in the lack of two threaded holes to the back of cylinder head just below where the drive goes. Secondly, earlier cars had a drilled & tapped hole in the centre of the inlet camshaft - that is not the case with the XJ6 cam. The final hurdle is the lack of a semi-circular hole in the cam cover (they did leave the semi-circular hole in the cylinder head but it's plugged with a rubber bung). The first hurdle could be rectified provided enough care were taken I suppose, using another head as a sort of template. Hurdle number three could also be rectified by fitting a 240/340 cam cover (or smooth covers provided the stud mountings matched thos on the XJ6 cylinder head). The biggest problem (in my opinion) is the camshaft drilling. I don't know whether fitting earlier cams would be an option - I presume the profiles are different for the XJ6 engine. For all the aforementioned reasons that is why I opted for the 420/XJ6 S1 tachometer.
If you do a search on google using 'XJ6 1975 3.4 cam shafts' it will bring up an interesting article on the jaglovers forum covering this very problem.

Fell free to message me if you wish. Good luck !

 

Keith,
yes I understand about the tach generator in the 3.8.

the dumb question is: how does the 420/ XJ-6 tachs read the rpm's ? Or any other engine for that matter, whether Jaguar or Chevy or....
.
there

 

The XJ6S1/420 tacho is connected to the coil circuit and I believe it works on the pulses generated, sending that info back to the tacho.

 

Keith,
attached are pictures of the 4.2 block I am preparing for a thorough cleanup.

I marked the Low Oil Warning Switch and other items to confirm with you.
the last rectangular fitting at the leftmost of the picture I don't remember what was connected there, but I can look in my XJ-6 to confirm.

So the question is: Do i remove the Low Oil Warning Switch and just thread a bolt there? (you can see the 4 new bolts I put where the power steering pump bracket was mounted)

Also, what did you do about the 4.2 three belt pulleys and damper? Did you use the 3.8 damper and single pulley? (picture below).
Thanks.

* By the way: the speaker panel you modified for the extra gauges is awesome work.




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(double post - deleted)



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Hi again,

Thank you for your comments Jose. The oblong steel item to the left of the oil filter is where the oil pressure sender goes (to feed the factory oil pressure gauge). You've correctly marked the low oil pressure switch near the distributor - you'll find that the femael thread on that item is 1/8"NPT (tapered) and it screws into a short hexagonal adaptor (as I said earlier it's essential that you leave that adaptor in place otherwise the oil flow would be interrupted). The brass fittings supplied with my new oil gauge came with a 1/8NPT adaptor which the small bore plastic pipe fitted into (see attached photo). With regards the damper assembly - I can't recall which one I used - it may have been from a 420 or an XJ6 without power steering as its a tw-belt version (again, see photo). As I said in my original post, the filter housing was from a S2 XJ6 with an upward pointing filter (I think they are now quite hard to find as they are alos used on Cobra's etc that use the Jaguar XK engine. They do occasionally appear on Ebay however.

Kind regards Keith