Welcome to hell(long w/ photos) Series 1 xj6 core plugs corrosion head studs

I do recall reading about a test that Jaguar did with a Mk2 as unleaded fuel became a reality. So the story goes they ran the car for 30,000 miles after a cylinder head R&R and setting of valve clearances. Post the long drive the found no perceptible/exceptional wear. Our car has 149,000 miles up with rebuild at 141,000 miles in about 1990. Still has original valve seats. All shims are within normal grading. FWIW. Paul

IIRC , Jaguar has used Stellite valve seats for decades.

Another great post, Thank you. Sandā€¦ My buddy who use to work at Jaguar engine recon(ditioning) I believe he said that ā€œthe shit for brains blokes that worked in castings werenā€™t very thorough about getting all of the sand out of the castings, around the front and the rear of the blocksā€. Also if people didnā€™t change their coolant regularly it gels and build up in the corners where water circulation is poor.

Cleaver about using the jack. Iā€™ve got a hoist that Iā€™m planning to use (on the Series II blown head gasket). My buddy also said ā€œin order to get the head off, youā€™ve got to be dead nuts parallel with the block in order for the head to come offā€

Ignorance is bliss. I have an 18 year old daughter. Iā€™ve learned with her there are certain questions that I donā€™t want to know the answers to :confused:

Thanx for the post Iā€™m enjoying it.

Mark

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There is no need to worry before you strip the head, Demianā€¦:slight_smile:

Excessive recession is very scarce - and there is no evidence from your pictures that your engine suffers from it. Unless there is clear damage to seats requiring further grinding; do a simple valve job - just verify that the valves are straight before reusing themā€¦

Frank
xj6 85 Sov Europe (UK/NZ)
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Well thatā€™s reassuringā€¦thanks for that.

As a side note, what are your thoughts on steel valve guides? I read, as ever, mixed thoughts.

Should i find issues should i replace with bronze alloy?
If all ok simply replace seals?
Intake only?
Teflon(if i can find) preferred?

Iā€™ve read adding to exhaust side can actually reduce needed lubrication.
Thoughts?

Thank you very much!

Just re-reading through the thread can you confirm if the piston is coming up flush with the top of the block or are they still a bit down? The land closest to the bore should be almost flush.

Hmmā€¦honestly i canā€™t say now.
Itā€™s all sealed up as shown, need to focus on stud removal.

Oddly i set it quite a bit before TDC when i removed everything. Needed to rig something up so cam sprockets could rotate as i rotated damper by hand checking inner bore dimensions a bit.

Didnā€™t consider that as issue unril after.

I donā€™t know. Hate to add confusion saying anything just yet, however top of each bore has an equal, darker patina at top of letā€™s say 5/16in eyeing it.

Hating to add confusion again or create situation that doesnā€™t exist, BUT the height appears equal to the dome of pistonsā€¦which i am certain are 8:1.

It struck me as the piston should be flush with the block as you say, yet i cannot imagine a reason they could not be if they were not supposed to?

Lastly, the amount Iā€™m off isnā€™t that much at damper.

My main concern initially was the damper being off, therefore screwing up timing later, however i see nor felt any evidence of that, though will investigate further later on.

Anyway, curious and my motive for initially mentioning it
Once again, the motor is all original to the car, 1972. A Federal car anomaly if true?

They all cannot be precisely and equally incorrect. Again I can think of no mechanical failure or flaw which could create such a condition for all pistons not to arrive flush with block face if they were intended to.

Again, hate to say anything further until i rotate it a bit CW to actual TDCā€¦but it isnā€™t much off.(?)

The darkened patina ring I am referring to at top of cylinder bores can be see through the grease.
(And yes I cleaned out those blocked coolant passages and carbon residues around studs are not corrosion)

The patina you are seeing is the ring ā€˜wearā€™ point as they are lower on the piston. That is what I would expect to see. From that I would be confident that the pistons are reaching the top of the block. Just locate the cam gears in the carrier ā€˜earsā€™ and check that the chan doesnā€™t ā€˜hangā€™ while rotating the crank.

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Understood.
Genuinely appreciate your time and experience.

Itā€™s been several lifetimes since Iā€™ve done this stuff.

Yeah, i created a little setup for the cam sprockets to rotate freelyā€¦

On to those studs!
zzzzz

Kind regards

I would just get on with it and set tdc before putting on the headā€¦ the darker portion in the bores is from the rings of course. You donā€™t want pistons perfectly flush with the top because you could never skim the block without replacing pistons, and I do not dare to imagine what would happen at high rpm with no gap!
How much of a gap there should be is nowhere to be found? I donā€™t know, nothing in the archives etc.?

David

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Turn the engine to max #6 piston height, Demian - using the dial gaugeā€¦

ā€¦wherever the pistons are then; this is(!) engine TDC - no ā€˜ifsā€™ or ā€˜butsā€™. At which stage the timing pointer should point to ā€˜0ā€™ on the timing scale. If it does not; either the damper has ā€˜slippedā€™, or the pointer is bent.

Pursue and rectify - in due timeā€¦:slight_smile:

Frank
xj6 85 Sov Europe (UK/NZ)
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As Robin says, Demian - the cylinder wear is main due to rings, and a ā€˜ridgeā€™ may form at the top of the cylinder in well worn engines. There is even a special tool to remove this ridgeā€¦:slight_smile: :

Frank
xj6 85 Sov Europe (UK/NZ)
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Jaguar used cast iron, Demian - I would go for OEM, but read the workshop manual on guides if you are changing themā€¦

Just check motion of valves in the guides for wobble - it is pointless to replace the guides ā€˜precautionaryā€™. The valve stem seals are only fitted on the inlet valves - and should be routinely replacedā€¦

When you start disassembling the head; each part to be reused must(!) go back to where it came from - so keep close track of themā€¦

Most likely; what is required on the head is just a routine valve lappingā€¦:slight_smile:

Frank
xj6 85 Sov Europe (UK/NZ)
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there is a risk in replacing guides, the correct procedure and interference fit is criticalā€¦see archives

therefore, if their is a need, some advise k-line guides instead

I would not modify exhaust valves

I have seen recessed valve seats on heads older than '71

(I took them to a fellow who has rebuilt hundreds of Jaguar engines, and he agreed)

If your engine had few miles?, those parts may still be in acceptable condition

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Iā€™m hoping everything will be ok.
Replacing guides would have to go to a machine shop as i have no way to heat the head.

The iron guides are okā€¦Iā€™ve read nothing bad about the original iron guides. Iā€™m just getting carried away here.

Reading on k-liners makes me uneasyā€¦I wouldnā€™t consider them personally.

Oh yeah, got itā€¦Completely appreciate and understand.

Out of curiosity, and just to get all ducks in a row, what is the special tool mentioned regarding worn area at top of bore?

I hadnā€™t any, but am curious.

A ridge reamer: still have mine!

ABSOLUTELY needed on old Rovers, to get the pistons out.

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Found what I rememberedā€¦

Some other changes were clearly improvements - for instance the much revised long stud block gave a more direct load path between head and main bearings, provided more secure clamping pressure on the head gasket and eliminated the bore distortion which had become apparent from stretching the block to 4.2 litres. (This lesson was not forgotten when the AJ6 block was designed - the head clamping stresses being taken down via heavy ribbing in the outer wall of the structure).

David

IIRC, there was a Rover engine, late-80s, to mid-90s, where the cam tower bolts went through the head, and into a main bearing web, taking that idea to its logical extreme.

On 2000 SC/TCs, the cam tower bolts WERE the head bolts, making adjusting the valvesā€¦interesting.

That is interesting stuff, thanks Paul.

Thank you David very much for link and thoughts.
I of course know of that article and have read it a couple timesā€¦ Iā€™ll take a look at it again.

Havenā€™t done anything since, still awaiting studs from Australia. Strangely best price found.

Itā€™s just been to absurdly hot these days. 108F+
So been buying books :wink:

Recommend Jaguar: 50 years of speed and style. Buckley

Very nice to read and well put together.

If you own only one magazine, get this monthā€™s classic and sportscar greatest hits special edition for Jaguar.
Can be found at barnes&nobles.

Outstanding quality. Best images and nice articles. Pages so thick i think Iā€™m always grabbing twoā€¦

Apparently doing a series on various marques.
Worth collecting.

Fwiw
Kind regards