How is your timing chain tension? There are some forums where that is talked about as a possible problem. For example:
As you know, your 120 has the spring steel tensioner, which is
different than the hydraulic Reynolds tensioner in your 140. Check
the tension of your lower chain. You can do it by rotating the
crankshaft back and forth while placing your finger on the exhaust
cam through the oil filler opening. If the cam moves with the
crank, then the tension is OK. If you have play in the rotation of
the crank, and the cam doesn’t move, then your lower chain
tensioner isn’t preloading the chain. This would cause the chain to
sling out against the tensioner, and make a racket. Even a properly
functioning spring steel tensioner will be noisier than the
hydraulic one. It could be just the sound of the chain rubbing on
the tensioner. Since I can’t hear it, I can’t say for certain.
This is our world renown Hydraulic Timing Chain Tensioner Kit for the XK120 and also Early XK140 version engines that used a spring blade type chain damper.
It replaces the C2156 / C4100 / C8245 tensioner blades and C2284 / C4101
springs, which are prone to wearing through and dropping into the bottom of
the timing chest at the front of the engine.
This kit is based on the original, Jaguar Racing Division's racing conversion
for the engines as used in XK powered race cars such as the iconic
C-Type Jaguar in the 1950's.
The oil spray bar is removed and the oil flow from this point is re-routed
to a later XK150 type hydraulic (self adjusting) damper assembly (and it
is advised to have the conical filter fitted behind to prevent oil blockage).
So no more rattling timing chain........ ever, after you fit this popular and
The adapter is a brass block and will require fettling at the back, as shown,
to fit the various different engine castings that Jaguar evolved during
this early period of the XK engines long life. We cannot accept kits back
after they have been fitted or modified for fitting, so make sure you have
someone competent to fit it properly.
This kit comes with damper, adaptor block, bolts, gasket and instructions.
You will see this sold in many places, marketed under lots of companies
own names. Come direct to the actual first line manufacturer, supplier and
specialist to ensure you get the right parts, fitting information and advice!
If you want to cure the other XK120 main engine fault, see our
XK120 Front Crankshaft Seal Conversion Kit SE823 - to cure the annoying drips!
Our part number is SE822.
Original Jaguar part number is not relevant as this was a later modification.