Loose upper timing chain

This is continuation of a long tread on E Type forum in hopes I can get help.from other classic 6 cylinder owners Let me describe my problem in a list:

  • I bought a 1968 Series 1.5 E Type which was non running and I have no knowledge of its history. I suspected engine problems.
  • First I ran cylinder compression tests with generally good results except 2 cylinders
  • So I removed the head and had it professionally rebuilt. Everything ok except two bad valves which were replaced
  • The head and p customs look visually good and no cracks (so.I was happy)
  • I reinstalled the head, connected upper timing chain sprockets (with one bolt on each) and maximized tension on eccentric spindle, all strictly in accordance with both Jaguar and Haynes maintenance manuals.
  • All well exact when I turn the crank by hand to expose the other spindle bolt hole, the chain and sprockets do not rotate
  • The chain looks in good condition as do all teeth on the intermediate gear which should turn upper chain
  • I have them tried researching sprockets about 5 times without success, with big efforts to ensure idle gear is in lowest possible positions
  • If I pull up on both outer sections of the chain, the chain engaged the intermediate gear and will not rotate
  • So.My first instinct is that chain has worn and is too.loose
  • But that contradicts with info that cams obviously turn during compression tests rotating engine with starter motor - i.e. Before I removed the head.
  • So it seems that I have done something wrong but I don’t know what and I am hoping for good suggestions

APOLOGIES for this long story but I am trying to anticipate as many of your questions as possble.

Typo correction s:
P customs should read piston
Researching should read re -attaching
I hate the spelling corrector


You don’t need to do a second post to correct errors in your first. Just edit your first post - much less confusing. To edit a post, just click on the pencil symbol below your post and a window will open that allows you to edit it. Once you’ve done this, I suggest that you delete your Correction post - to do that, click on trash can below it, and it will be removed in 24 hours.


That means, in high likelihood, you’ve pranged a valve.

Perhaps, if the crank was rotated 15 degrees or more while the valves were stationary, but that would be a new problem. The question remains why the upper and lower chains are not moving in sync.

The lower chain engages the bottom of the gear keyed to the crankshaft and the top of the larger sprocket in the tandem intermediate gear, which means that the smaller sprocket must also be turning. If the upper chain is not moving with the intermediate sprocket it must mean that the upper chain is not completely engaged in the bottom of the smaller sprocket of the intermediate gear. There is no other explanation.

If the upper chain has excess slack on one side, as the engine is turned clockwise it may begin to engage the intermediate gear and the cams will just begin to turn until the slight slack on the other side is taken up, increasing the slack in the chain sufficiently that the loop of the chain falls below the intermediate gear and loses its engagement. We don’t know if the head was shaved and the block decked in it’s previous life, which in combination with worn components and standard head gasket could exacerbate the problem.

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I think this may be where it’s going wrong. Maybe semantics. With the sprockets bolted up to the cams, are you able to make the chain between the sprockets a lot looser by turning the adjuster fully clockwise?

I hear crickets.


Maybe the chain was only just engaging the lower sprocket before the head was removed, and now that you’ve had the head repaired, it has been shaved, (and maybe installed a thinner head gasket) and the chain is now slipping past.

Maybe time for a new set of chains…


Post some photos and it might make the problem clearer.


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The sprockets will turn (should turn) even without the head being in place.

What was wrong with the valves that were replaced?
And secondly can you confirm that you did observe the cams turning when you did the compression test?