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robin craig

J60 Jaguar 4.2l engine variations

Question

I was speaking with someone yesterday who stated that there were variations in the design of the J60.

 

I am told that some had dry liners and some did not and there is a way to tell the difference by the engine serial numbers.

 

Can anyone shed some light on this subject?

 

R

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The engine data plate should say something like J60 Mk100 or Mk101, A or B. The Mk100 was linered, the Mk101 slotted. A was for CVRW, B was for CVRT.

 

Chris

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Chris,

 

thanks for the response.

 

Is there any longevity issues associated with these engines ie desireability of one versus the other?

 

R

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The engine data plate should say something like J60 Mk100 or Mk101, A or B. The Mk100 was linered, the Mk101 slotted. A was for CVRW, B was for CVRT.

 

Chris

 

Hi Chris,

 

Not sure what you mean about a 101 being "slotted", they were un-linered blocks. There are differences in cylinder heads and gaskets between the 100 and 101.

Also the designations might not always run to rule, as when in service we sometimes had to convert one to another if there was an availability issue. Usually convert a B to an A due to the survival rate of Fox engines being low. Why they never fitted a limiter as the CVR(T) had we will never know, but I do know from experience that I left the limiter on when converting, bet the drivers cursed when they could not keep up with their mates!

 

regards, Richard

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Richard,

 

I copied that text out of EMER Power S579 Mod Instr no 15... I don't know what it means either!

 

Chris

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Richard,

 

I copied that text out of EMER Power S579 Mod Instr no 15... I don't know what it means either!

 

Chris

 

:D yet another mistake in EMER's ! It is surprising the number that come up still.

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From the J60 EMERS:

 

"mk100 engines converted to mk101 at overhaul by incorporation of non-linered cylinder blocks are to have original engine number suffixed by /1."

 

I believe the mk100 cylinder head can be converted to mk101 with a moderate amount of machining..

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The 'slotted' block refers to 5 slots being machined in the top face, one between each cylinder. This was done to prevent cracks appearing between the cylinders at this position.

 

The early military use of this engine highlighted a serious cooling problem, presumably because of the engines relying entirely on fan cooling (not assisted by natural forward motion wind through the radiator, as in the cars).

From experience of testing the limits of many engines, it's usually the oil temperature that sets the limit of how high an ambient temperature can be tollerated. This may also have been a factor as the sump and any oil coolers are not cooled by vast amounts of air passing them.

 

The early blocks also has their coolant holes to the head enlarged and additional 'block to head water holed' drilled (we always use the term 'coolant'. not water, to avoid confusion) in an attempt to improve cooling. Hence the 2 types of head gasket.

 

Here is a quote from my EMER 2300-E-200-533

' Two types of cylinder block in use. Mk 100 engines-linered, combined blocks with full length dry liners and crankcase.

Mk 101 engines - slotted, combined block with siamesed bores for cylinders, additional block to head water transfer holes and water slots instead of water ports between cyliders. Integral crankcase.

Mk 100 engines converted to Mk 101 at overhaul by incorporation of non-linered cylinder blocks are to have original engine number suffixed by /1.'

 

Here is an early prototpe Fox engine..no liners, no slots, no ribs.

Engine46.jpg

 

Here is an early Mk100B Scorpion engine, liners, no slots, ribbed block

01012007027.jpg

 

Here is a later Mk 101B Scorpion engine, no liners, slots, ribbed block

Fox7004.jpg

 

Early blocks are quite different, and easy to recognise. No ribs

 

Engine49.jpg

 

Engine410.jpg

 

And here is a later Mk101B..with ribs

FinepixNov09056.jpg

 

Now have we all got that? Or do I have to go into more detail?

 

Sorry about that, I do have a thing about these engines.

 

All Mk101B

9106.jpg

 

And the final test..3 Mk101A and the prototype Mk100A..spot the difference!

4eng5.jpg

 

Jon

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Thanks Jon,

 

All coming back to me now, I do remember the slots, a long time ago since I was knee deep in that stuff. Fox was good for workshops, alway kept us busy, never seen so many catastropic engine failures as in those.

 

cheers Richard

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Dear Jon,

 

Nice row of Fox engines, is one of those ours?

 

Thanks to all who have contributed in this. I feel it so very important to air these issues so that other newbies to the game understand what you old sweats know.

 

I feel vastly more wise now, I will go look at that Belgian Spartan engine that spat out a rod and see what type it is, perhaps that will explain why.

 

Thanks

 

R

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Yes Robin, one of the front ones is yours I believe. There were about 7 Fox engines going through my workshop at the time.

 

On the subject of unreliability of Fox engines...here is my theory:

 

One of the Foxes I purchased at the Jackson's sale had spectacular evidence of catastrophic engine failure. From the large quantity of debris (that had been saved in one of the flotation bins) and the remaining devastation, I conclude that the following series of events had occurred.

 

The engine had had a major seizure whilst the Fox was travelling at high speed. The momentum of the vehicle and the action of the gearbox, fluid flywheel and transmission (being effectively a direct geared system at this speed) had ripped the engine from its mountings and rotated the complete engine several times within the engine bay. The fluid flywheel had exploded into about 50 pieces, taking with it the bell-housing and rear gearbox flange, which suffered a similar fate.

 

There were pieces of the rear engine mounting,sump and fan gearbox in the debris, so I presume these were also involved!

 

On it excursion round the engine bay the engine had shredded both rear propshafts and all the oil cooler installation, meanwhile severely damaging the firewall and turret floor steelwork. Finally, having nearly ripped its way into the turret it mangled the rear of the commanders seat...which must have been quite a surprise for him!

 

One can only imagine the event from the crew's point of view. There would have been quite a sustained noise, followed by a large quantity of steam, oil, petrol and high speed hot debris, not to mention sparks from both mechanical abrasion and the severing of the starter feed cable!

 

 

I have pondered for some time about the cause of this event and have narrowed my mind to some possible reasons.

 

1. The engine just threw a rod, which jammed the engine solid instantly...not very likely..I have many engines with thrown rods and they just tend to break the sump (not even that sometimes) and make a lot of noise!

 

2. A snapped crankshaft allowing the fluid flywheel to explode, taking the bell housing, disconnecting the engine from the gearbox and front engine mountings...again not very likely, as the input shaft to the gearbox was not damaged (and indeed was re-used in the subsequent restoration).

 

3. A driver's mistake...changing into a much lower gear whist travelling at high speed. This is easily done on a pre-selector gearbox (the Scorpion's sequential change makes this much more difficult, he can only really do one gear at a time) (also on a car type manual, or automatic gearbox it's not easy). I would have thought this action would have disintegrated the gearbox before achieving sufficient engine revs for an explosion! The jaguar racing boys can get an incredible speed out of these engines (when properly balanced).

 

What do you think?

Perhaps this explains why the Fox engine was not as reliable as a similar Scorpion one!

Why doesen't this happen on Ferret (or even Dingo, Saladin etc.)?

 

Fox gearbox with most of the damage removed.

3gearbox2.jpg

 

Gearbox rebuilt (in situ)

3Gearbox1.jpg

 

Jon

Edited by FourFox

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See that damage on a vist to Jon a few years back, makes you think "What if?" scary!!

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That sound very scary.... do you have any pictures of the damage, because I really cant comprehend such damage it must have been going really really fast when it happend.

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Sorry, I didn't take any pics of the 'before' situation. I probably have some of the bits left. I will have a look in my scrap pile.

The Fox was sold some time ago to Graham in the NE. I believe it was still going ok when recently put up for sale!

 

Jon

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I have just found pictures of the 2 different types of J60 head gasket. (for all you anoraks out there)

 

Early type Mk100...no inter-cylinder cooling holes or slots.

Engrebuild3.jpg

 

Later type Mk101..showing the extra cooling holes.

1013.jpg

 

Note the home made timing distibutor. It ensures that you get the distributor gear on the same cycle as the camshafts, an not a tooth or two wrong, or even 360 degrees out...a common fault without one of these!

 

Jon

Edited by FourFox

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Hi Robin

 

Yes..it is very useful.

I borrowed an ex-Alvis one from Andrew some time ago. It is such an essential piece of kit I decided to make one for myself.

 

Remove the insides from an old distibutor, leaving the drive shaft and offset driving dog intact.

Its better to use one with the advance/retard weights stuck, otherwise super-glue these so they won't operate.

Fabricate an aluminium deck plate and bolt on instead of the points/electronic mechanism.

Put in place on an engine (which you know has the distributor skew gears correctly timed) with both camshaft slots at right angles to the cover face (i.e.TDC). Check the flywheel timing mark!

Cut half of the rotor arm locator spiggot away, in a position closest to the electrical connection bulge on the distributor.

Make a metal pointer that points to the center of this bulge in conjunction with bit now missing from the rotor arm locator and fasten this to the ditributor shaft using a longer centre bolt.

Mark the centre point as accurately as possible.

I mark 5 degrees either side of this to give a good indication of being one tooth out in the skew gears.

 

Hope this is useful. You can see another picture of it on the second engine picture on the first page of this blog.

 

You will need a pair of camshaft slot locating plates to accurately set the valve timing...and then to set the static ignition timing. these are easy to fabricate from 6mm (sorry 1/4 inch ) plate.

 

Jon

Edited by FourFox

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Wonderful information!

 

Am I correct in my thinking that a rebuilt engine with a new style ribbed, slotted, linerless block will have its original serial number suffixed by /1 and an engine of a later manufacture date will have the newer style block and the /1 stamped as part of the original serial number?

 

Secondly are the improved engines definitely known to be more robust than the earlier type? Would it be unwise to consider anything but a mk101 engine as a replacement for a CVRT?

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Jon, back in the 1970s I did a lot of work on Jag XJ6s, mainly Series 1/2, they all had dry liners and many had cracked blocks. The simple repair was to fit a brand new engine from Jaguar which cost just £630 fully dressed except for alternator and starter. Were the slotted blocks ever introduced for car use or were they a military special?

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When I post a question like this and the responses come back with so much information it really makes me glad that I have managed to get all this information out into the public domain to hopefully be around for a very long time as a resource for others.

 

Thanks Gents

 

R

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"Jon, back in the 1970s I did a lot of work on Jag XJ6s, mainly Series 1/2, they all had dry liners and many had cracked blocks. The simple repair was to fit a brand new engine from Jaguar which cost just £630 fully dressed except for alternator and starter. Were the slotted blocks ever introduced for car use or were they a military special?"

 

I believe the 1968 prototype Fox engine I have is one of the first 'conversions' of a domestic automobile Jaguar 4.2 for military use.

I am led to believe that the subsequent basic changes to satisfy the military requirements, especially in improving the cooling system and also to reliability were all incorporated into the civillian production. The later XJ6 engines are very similar (apart from the pistons) to the later Mk101 military ones. Even the camshaft covers and breathers were used (although they were painted black).

The military sump used is a simplified variation of the 1960s E-Type ribbed sump.

 

Engine45.jpg

 

I have seen new crated military engines dating from the 1990s, although by now the long stroke, cast iron block engine was getting a bit old-fasioned. Still not bad for a design that was over 40 years old!

 

Jon

 

 

Edited by Marmite!!
quote tags added

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Yesterday I had the opportunity to examine a Jaguar engine from a 1978 car. The block has the ribs mentioned earlier & the previous owner thought it had been rebuilt. Often though a huge repair bill equates to "rebuilt" to some. Would any part of this or a similar engine be directly useable in CVRT configuration?

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Fascinating thread, thanks for starting it, Robin. The depth of knowledge on here, Fourfox and others, never ceases to amaze.

My interest is as a CVR(W) crewman (RY) from the Fox's introduction 1981/2? until I left in 1987. I cannot recall ANY engine failures in our Squadron (That doesn't mean there weren't any, I am very aware of that!) but quite a few gearbox failures.

I remember being appalled, as ex Saladin, Saracen and Ferret drivers, at the temperature guage readings. As I recall, the normal running temperature on the 'standard Army Temp. guage' was off the clock. I vaguely remember hearing tales of 'porous cylinder heads' due to the higher than 'Normal' running temperatures, but cannot recall suffering any in Squadron.

 

Great thread, just what this forum is SO good at!

 

 

'Chas.'

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Yesterday I had the opportunity to examine a Jaguar engine from a 1978 car. The block has the ribs mentioned earlier & the previous owner thought it had been rebuilt. Often though a huge repair bill equates to "rebuilt" to some. Would any part of this or a similar engine be directly useable in CVRT configuration?

 

Jack

 

I think the state of tune was very different although i am sure there would be some interchangeable parts.

 

If you think this thread is good you should get jon round the campfire with a can of beer at 1am..!

 

Cheers

Timbo

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My interest is as a CVR(W) crewman (RY) from the Fox's introduction 1981/2? until I left in 1987. I cannot recall ANY engine failures in our Squadron (That doesn't mean there weren't any, I am very aware of that!) but quite a few gearbox failures.

 

 

 

Hi Chas,

 

You were obviously not with C Sqn RY ! We used to carry out all repair work for their Fox's ( and other regular units), from when they came into service, which was some years before 1981, I am sure it was 1976. I worked on them during the whole of there service life, which was nearly 20 years I think. Gearboxes suffered badly at the start, and the first major exercise to Germany really tested them. The second gear band was wearing quickly, this was found to be a flat spot in the carburation, just as you were pulling away the engine would fluf and the driver would dip his gear pedal and blip the throttle, consequently slipping the gear band. mods were issued with different jets for the carb, I think several goes were made at this, and never really solving the problem, until Marcus took over manufacture of the carb from Solex. Then it was realised the problem was in the throttle body, a new one was produced, accelerator pump delivery was reduced by 30%, to reduce "bore wash" and new non-return valves fitted. Unfortunately this did not occur until near the end of the Fox service life, but made a dramatic difference to its performance.

 

As for engine blow ups, have changed many J60 with large lumps missing out of the cyl block wall. Fitted a recon J60 once, it went out with the Examiners on road test, wthout a problem, then the above mentioned unit collected it to drive back to base, 4 miles up the road, BANG !!!!!! a camshaft broke in three places ! I once heard guys from the unit say they had about 100mph coming down the motorway, well having been in the turret of one in the early days at 90 mph, on a short stretch of road, I can quite see why the engines blew so often.

 

regards, Richard

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