Hot cylinders 1 & 4

Not on any XK Engine I ever worked on: perhaps the earlier engines…

XK120 Manual pg B28
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pg B31
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Aha! The 120 was the odd dog out: apparently, that is s bit of data that slipped the brainium.

So they changed it? I wonder why, and when?

Not sure of the break point, but fer shure, 3.8 and beyond, it’s a different orientation, with the slot at an 11-4 position, and long side forward (always hafta look it up!).

Can’t think of any reason for why they would make a change.
Ken Ball’s Autobook for '48-'61 models published 1969 reprinted 1973 says parallel, nothing about 11/4.
Chilton’s does not cover it.
I don’t have any later manuals.

They changed it.

Definitely 11/4 on my 3.4 and 3.8 S engines.

What book is that? It’s curious that no reason for the change is given.

It’s a Jag manual, an image posted on an older thread.

Tis odd they’d change it, but there must have been a reason.

I’m refitting it all this morning and following the procedure in the manual for Static timing. However the final part advises to turn the distributor until a spark just jumps ( see text below). What it doesn’t say is whether to turn clockwise or anti-clockwise ? Also it seems to need a fairly quick turn to produce the spark, which isn’t great for fine adjustment.

Davey
Set the pulley marks to the pointer, 6deg or whatever your car requires, #6 front piston.
Set the distributor loosely and start with the body of the dist. in the most anti clockwise position, now turn the ign. on and rotate the dist. clockwise very slowly while watching the plug on #6 front piston.
As soon as you see the spark , clamp the dist. secure.
When engine is running do a final check with a strobe light.

All back together, started fairly easily and no difference whatsoever ! Temperatures are No6 205°C, No5 205°C, No4 340°C, No3 240°C, No2 205°C and No1 335°C all measured on the exhaust header as they exit the manifold.
Those temperatures are a lot hotter when the Auxiliary Starting Carburettor is on with 1 and 4 being up in the high 400°C range ( I think about 480°C ish )

Just to be sure I checked the compression. All good and all fairly even around the 130psi mark.

Ultimately, this is a cam problem. Nothing else. Put the engine on TDC with the dist. pointing where it should be. Wire the cap as it should be. Stay out of the pan. Now go to the top of the engine. You will see the cams are out by 180 degrees. Take them out and install them correctly. Problem solved. It’s a lot easier to change just the cam cover gaskets than the oil pan gasket.

That would solve the distributor being 180 deg out.
No way is it going to correct the difference in temperatures.
Are the valve clearances correct?

Turn it against the direction of rotation of the rotor, standard procedure for any distributor with points ignition

I was very hopeful the Cams would be the answer. However having put No6 at TDC this is what they look like, with the alignment notches clearly visible at 12 o’clock position where I believe they are supposed to be.

P.S. it’s electronic ( constant energy ignition ) not contact breaker.

Have you got a cam alignment tool to confirm the cams are both truley at 12 oclock when 1 and 6 are at TDC? It is easy to get uneven fuel mix from carbs to result in unbalanced exhaust temps. Especially with starting carb in play. If it runs and timing is right I would start tuning idle mixture carb tuning after all up to temp.