Working on a 1959 MK1 3 1/2 does anyone know where the timing marks are to properly install the timing chain?

 

There are no timing marks ! I'll bet that sounds odd, and it is, a bit. What there is, is the camshaft timing plate.
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With the cam covers off, you set the engine with TDC on cylinder number 1, which is, (typical of Jaguar) the one at the rear of the engine, by the fire wall). You should see a small slot at the front of each camshaft. This is the "timing mark". You use the tool to make sure each camshaft is in the correct position. The tool will only slot into the camshaft if the slot is perfectly aligned.
Are you replacing both timing chains, (upper and lower) ?

 

Actually there are TDC timing marks on a MK1. The 2.4 has an aperture on the left upper side of the bell housing to see the flywheel. The 3.4 has a timing mark on the flywheel but you have to be under the car to see it as it is at the bottom of the bell housing under a cover that has to be rotated clear.
I have just checked my original workshop manual on the above points as I have owned 5 MK1s and my memory is correct.
Actually the workshop manual says to put the car at TDC referring to no 6 cylinder (which is the front cylinder) with the distributor rotor arm pointing at no 6 in the distributor.

Bill Mac
current
MK1
MK2
S3 XJ6
X300
Previous too many jags to name

 

Thank You For The Info. That helps a lot