Hello, a couple of weeks ago I posted regards removing the cylinder head from my Mk2, thanks for all of the tips.
Progress to date: Started the process this week and now at the stage of removing the cam sprocket’s. Reading through the manual it clearly says not to rotate the engine once the sprockets are disconnected…so fa so good. I started by setting the cams at TDC and confirmed with the valve timing gauge. I have removed one of the set screws from each sprocket. The next step according to the manual is to rotate the engine until the 2nd set screw in each sprocket can be accessed and removed.
My question is, by rotating the engine in order to remove the set 2nd set screws the cam / valve timing will be incorrect as the valve timing gauge (presumably) will not fit in the notch. This is not an issue for now, however when refitting the cylinder head what do I need to do to line everything up?
Now for the “almost a disaster bit”.
When cutting the locking wire a piece about 2cm long fell down onto a small ledge in the timing cover. Not looking forward to removing the sump to get at the timing cover I magnetized a long screw driver and as luck was on my side picked up the offending piece of wire. Packed up the tools and called it a day.
I remove the cam bolts that are inaccessible while at tdc, then turn the engine to tdc and remove the other bolts.
Now you know why you need to stuff the chain area with towels!
Thanks David and Robert, yes that makes more sense than the shop manual, turn the engine to get the 2nd lot first…then back to TDC. Yes not sure why I decided to proceed without putting something around the chain area, given the extra work if something ended in the sump…must be old age catching up!!
Well the cylinder head came off with very little effort. I managed to remove all of the engine studs, except the locating stud, plus a couple of taps with a large rubber mallet and presto, off it came with the help of an engine crane.
Observations:
The thin steel gasket had rusted around some of the water jacket passages, mostly on the exhaust side. Six of the dome nuts would not unscrew from the studs in the middle of the head. Two of the combustion chambers were clean mostly free of carbon, likely from ingress of water. The air cleaner bracket legs did not have any washers, and three of the associated studs were part of the group of six that the dome nuts remained on the studs. Did a home leak test, after removing the cams, inverted the head and filled each combustion chamber with petrol. all except No1 leaked either through the exhaust or inlet port…no. 4 was the worst with the fuel running out the inlet quickly. Also checked the valve clearances… the exhaust side was mostly OK, with one each at 5 thou and 7 thou. Different story on the inlet side. Only 1 at 4 thou…two I could not measure, as these were at under 2 thou, and the remaining 3 at 2 thou.
Now the good news:
Today I took the head to a machine shop, which I have known for 30 plus years and have had work performed previously. The folks are familar with Jag cylinder heads, they do not do a lot, however repair a couple each year. Initial tests showed the head not to be porous…it was about 50% higher than the figure where the head is likely unserviceable. Surprisingly a visual check reveals only a very small bit of corrosion around one of the water jacket ports near number three combustion chamber…so looks like virtually no welding will be required. Also an initial strait edge check shows the head to be flat.
Of course the head needs to be cleaned stripped, pressure tested and valves, followers, cam(s) guides all need to be measured, and the head tested for flatness / warping etc.
I have a couple of questions:
modifying the tappet retainer either with a plate or screw, so these do not move and damage the cam(s)…both inlet and exhaust or exhaust only.
Is it a good idea to put valve stem seals on the valves, I think these are referred to as umbrella seals…I did this once previously on an early (1960) MG engine and made a noticable reduction in oil consumption. According to the parts book these were not fitted to early (mine is 1964) 3.4 engines. The later engines had seals fitted to the inlet side only. If the seals are a good idea, is there a after market part suitable, eg the MG was fitted with umbrella seals from a Ford, without being modified.
Any suggestions regarding a VRS gasket set, in particular head gasket…preferably available in Australia…hopefully I can order one now and this will be to hand when the head work is complete.
I am a first time Jag owner so any help / suggestions / thoughts greatly appreciated.
The tappet retainers were a fix that came about after the emissions controlled XJ6, particularly the North American version, demonstrated a propensity to loosen their exhaust side tappet guides. Those engines ran much hotter than the earlier varieties. You probably won’t need them on a street driven saloon, but it doesn’t hurt anything either.
Valve seals are a case of shifting expectations. In the old days, a puff of smoke on start up was to be expected, as was some consumption. The Japanese and the Germans found this offensive, started fitting higher quality seals and gaskets. After a few years, that puff of smoke became associated with a perception of low quality. The intake valves operate exposed to manifold vacuum, so they can suck oil past the guides and during operation. When the engine is running, the exhaust valve generally operates in an environment that is above atmospheric pressure, so any oil between the valve stem and guide would tend to be pushed back into the head. By the standards of the 1950’s, Jaguar judged a little smoke and consumption to be of no consequence. By 1980’s it was a definite liability, and the later XK engines received umbrella seals on the intake side.
Try to establish (with your head guy) if the head and block mating surfaces have been machined. Too much can cause compression to rise to a point where pinging is a problem. If this checks out I would use a VRS with a composite head gasket - like a Payen. Top shelf is a Cometic gasket set. Head gaskets can be ordered in different thicknesses to compensate for machining per above. We get both in Oz.
Thanks Mike & Paul…I’ve used Payen in the past on a 1960 MG, without any issues. As suggested will wait for the machine shop, before ordering.
Today, decided to have a good look at the studs, six of them are pitted to deeply in my view to use again. Rather than mix and match old with new, I think it would be better to replace the whole lot with new. I have looked online at a couple of websites and they are available with one exception all seem unbranded, so quality might be an issue.
The only branded version was ARP, made in USA and little expensive, these studs do not come with a dowel stud.
Any recent experiences / thoughts with purchase of studs, either ARP or any other would be greatly appreciated. The car is for road use only so, the ARP type might be a little bit of over-engineering.
I got mine for our XJ6 from SNG ex UK. I don’t think that they were anything special. No issues after four years. They were long studs which would normally be more problematic. Don’t think that you will need to splash out for ARP’s. Just retorque after 500 miles or so and you should be sweet, 54 lbs-ft from memory. FSM has the details.
Slow progress on the Cylinder head. Inlet guides/ valves & seats ar OK. Not so the exhaust side, have sourced valves. However the engine builder is having difficulty sourcing exhaust guides, the old ones were 0.5015, so a fraction over standard, which I believe should be 0.501. Looking for 0.502 (if possible) Moss have a listing for this size, no clue as to quality, are there any other sources preferably from Aus, otherwise UK or US.
On another matter the exhaust cam had some wear on the base circle for cylinders 1,2 &3, so have sent these off to Tighe cams, which is close home. Have previously used this firm in the past, had them grind a new cam for an MGA …so happy with their service.
Yes, it surprised me as well…looked like a breakdown of the case hardening surface, also similar damage on the related cam follower(s). I checked the gaps on disassembly…the exhaust side was mostly ok…none at zero. Maybe some “grit” in the oil at a point in the past.
The bores are OK no scoring or any ridge at the top, and oil pressure is, according to the dash gauge, good.
