Jaguar engine rebuild/spares etc.

[spoodler]

I recently posted on General Gassing re: a modern straight six donor for my '36 Austin but have come to the conclusion that I would really like to keep the Jaguar engine that is in it. It's currently fitted with mainly manual Mk10 running gear and a Series 2 4.2 XJ6 engine. Having just returned from the Pistonheads do at Sherbourne Castle (one hundred and forty miles or so) I was able to estimate its oil consumption at around fifty miles per pint! Compression figures vary from about one-thirty to one-forty p.s.i. and the oil pressure drops off the clock. However, quite remarkably it is still returning twenty plus to the gallon and is smooth, surprisingly quick and sounds quite healthy! Because of this lack of nasty noises I am considering rebuilding the existing engine - fingers crossed that I don't find any major damage, never know it might just be valve stem seals...
I have rebuilt several older car engines and many 'bike engines (inc. modern DOHC Kawasaki and Yamaha) but have no real knowledge of the XJ unit. I have read on several forums that home rebuilds are not advisable but can't understand why. A read of the manual doesn't show anything that can't be tackled at home - any machining will be done at a local engineering shop - or have I missed something? Do any of you out there have any experience? Also, any recommendations for a good parts supplier as I have not dealt with any Jag' specialists yet?

In case you are wondering - the car was hot rodded in the seventies and was then neglected for many years. I have only just (two weeks and three hundred miles) put it back on the road with the engine that came with it.

[jagracer]

It's all quite do-able at home but depending on how far you want to go it could be cheaper to buy a re-con engine from the likes of VSE. Depending on the pistons you have then the CR could be OK so you may get away with new just bearings plus maybe a regrind if there is any crank damage.

[a8hex]

I terms of bits, you should be able to buy everything from SNG Barrat.
http://www.sngbarratt.com/

With a SII 4.2 block you've got long studs that run down through the water channels. These can corrode. If they break off, getting them out again can cost more than the value of the block. These engines aren't hard to find. You can check the state of the studs if you pop out the core plugs.

There is a Haynes manual on the XK engine.
The original owners manual for the earlier XK engined cars would have had sections of removing the head.

The engine is bloody heavy.
Getting it onto an engine stand can be a PITA. make sure you've got it in a balanced position. I once put one onto a big Clarke engine stand which should be well in spec for the XK, but had it mounted to high, because the engine hoist and the stand clashed. The moment I tried to turn it, it just escaped from me and spun round, badly bending the mounting plate on the stand.

Good luck

[XJ13]

spoodler said:

have read on several forums that home rebuilds are not advisable but can't understand why. A read of the manual doesn't show anything that can't be tackled at home - any machining will be done at a local engineering shop - or have I missed something? Do any of you out there have any experience? Also, any recommendations for a good parts supplier as I have not dealt with any Jag' specialists yet?

I entirely concur with Ken's sound advice. Despite what you may have read, these engines are easily rebuildable and most parts are available. I have rebuilt many of these engines for road and race. The S2 block is the best block to start with as it doesn't have the extra cooling slots cut into the metal between cylinders on the later engine and is the block I would choose if I was building a race engine.

In addition to the Haynes Manual there is a useful book called "How to Power Tune Jaguar XK: 3.4, 3.8 and 4.2 Litre Engines" available on Amazon at around £17. I also recommend you subscribe to the JagLovers Forum http://forums.jag-lovers.org as it is an excellent source of advice with many very knowledgeable (and friendly!) posters.

Let us know how you get on.

[Huntsman]

I rebuilt my 3.8 at home, its yet to be run.

Its not a complex motor and the book advised above notes the major pitfalls.

As has been covered here previously, its important to get the o rings on the oi pipes right to ensure good oil pressure, I found the ones in the gasket set I bought were a poor fit.

I regret not fitting a lip seal to the back of the crank, I might pull mine apart again and do it before I fit it.

[spoodler]

Thanks for the replies. I think you've pretty much confirmed my thoughts on this but I couldn't understand why so many folk were advising not to touch. I have just discovered the Jaglovers forum but haven't found my way 'round it yet...looks like there is a lot of good info' there once you sift through the huge amount of stuff posted.
I've got a Haynes manual which I've already had a good look through and a CD parts catalogue from XKs Unlimited in the States which has some brilliant clear exploded diagrams etc. - they've been excellent at giving me an idea of the work involved - just thought there was something I was missing...
Also, would anyone know if there are any major differences between manual and auto' engines. As far as I can tell they share the same crankshafts. I only ask as my XJ6 engine is mated to what I believe is a Mk10 manual 'box. The clutch doesn't bite until the very top of the pedal travel, but also doesn't seem to fully disengage until the very bottom of the travel. I'm well aware that there are all manner of possible reasons for this (slave/master cyl', worn clutch etc.)I'll investigate when it is all apart but wondered if there might be a basic problem of incompatible components...
Thanks again for advice so far. John.

[varsas]

I am considering the same thing. 4.2 XJ series 1 engine. Similar compression as yours, high oil consumption (still monitoring this) but good oil pressure. As with yours it pulls very well, is smooth and starts very easily.

I assume you know there where two different compression ratio's? 8:1 and 9:1. The workshop manual is good on re-building the engine, it goes into very good detail about how to remove the camshafts and how to align the timing gear afterwards. This is the part that worries me, new fangled over head cam engines...pushrods are much easier!

Would it be easier to pull the head first? You can see if it is just valve stem seals, and inspect the bores/pistons etc. My manual also does say that you can change the piston rings without removing the engine from the car...Depends on how difficult it is to get the engine out I suppose.

If you do learn anything (especially what engine hoist & stand to use) I'd be interested. Even better a 'build' thread would be fascinating.

Edited by varsas on Tuesday 4th October 11:20

[a8hex]

varsas said:

If you do learn anything (especially what engine hoist & stand to use) I'd be interested. Even better a 'build' thread would be fascinating.

For an engine stand then I've normally seen these engines on the larger Clarke stand, the one with rating of 340KG, although I have seen them on the smaller 227KG one.
The big issue with the larger one is getting a hoist that fits with it. The engine hoist from the local hire firm (also a Clarke model) has a leg arrangement that makes in nigh on impossible to get the engine onto the stand. The smaller stand should be easier since it has 2 wheels at the back but then a single leg coming forward to the front wheel, so it should fit between the legs on the hoist. The large stand has two legs extending to the front so it wide both front and back so fouls with a hoist that has a v shaped leg arrangement.

The main thing is the weight of the damn thing. Its a big old lump. The head is fine, its alloy and easy to lift, just be careful with it. You can not lay the head down on its face when the valves and cam shafts are fitted, you'll bend the valves.

The performance and tuning book mentioned above is good too. It gives a lot of details on rebuilding these engines. I'm not sure his suggestions for ignition timings are right though.

I've dismantled one of these engine, but never put one back together. I was looking at building one, so I picked up a 4.2 engine from eBay for about £50 (I was lucky, it think it was actually in really good nick) just to see what they were like to take to bits.
It probably isn't the most forgiving of engines to work on.
You need to get the valve timing right or you'll wreck the valves.
Its big and heavy. I used to strip down and rebuild Imp engines many years ago, and you could pick anything up, even the long engine, transaxle assembly wasn't too heavy. But the Jag engine can't be moved around in the same sort of way. I guess the tolerances on the Jag engine are much finer too.

The other reason why there is probably a lot of advise about getting the XK engine worked on professionally is that a lot of the cars it runs in are worth a lot more with the original engine than with a replacement. If you wreck the engine then it could prove expensive to getting it fixed or you could loose money by changing to a new one. There are some excellent people on here who specialise in working on these engines. Last time a listed a few there were posting from people I'd forgotten but who's advise on here has always seemed sound.

In Jag lovers there is the XK-Engine forum and you might want to look in the XJ one too as that is where your engine comes from. I've always found everyone on the forums to be very friendly and helpful, I know others here have had different experiences. I used the XK (not XK8), XK-Engine and the X300 forums most, but occasionally I've need advise from people in others of the forums and they've been welcoming and helpful. There are often a lot of Yanks there, so shopping advise is often different. A lot of the people who use the forums are regulars so there is a lot of friendly background chatter, I've always found it helps to introduce myself and explain a bit about the car and what I'm looking for.

[varsas]

Thanks for that.

I won't be doing it until next Summer, otherwise the car would have to sit outside while the engine is in the garage.

I rebuilt my Land Rover engine last year (and it still runs!) and that was quite good fun. To be honest getting a pro to help isn't an option, the car is only worth about £3,500 and it'll cost more then that to have someone rebuild it. I'd be better off selling the car with a (possibly) sickly engine.

I'll check out that forum thanks.