Triumph Repair: 80 Spit Timing Chain Rattle, crank pulley, clutch pedal

Question
Near the end of the down side of an engine rev I get a rattle in the timing chain case.  I did have the cover off upon as part of the new gasket regime and noticed that the previous owner must have been plagued by this sound also as he put great amounts of body filler in the front face of the cover and then had it painted so as to hide it!  I managed to get the front of the cover looking as it should but I can only imagine that this sound is now louder.  Should I assume that a new chain and tensioner will do the trick or is this a sound that is common in the later Spits?
I would appreciate your thots on this - you have been very helpful in the past with a prior question that was answered brilliantly!

Answer
Hi Chris,

I have worked on many Spitfires over the years and I have never even heard a timing chain on a Spitfire engine. So there is something wrong there. I am not a fan of the timing chain and tensioner system but it seems to work ok. I believe if you can hear it over the normal engine noises there is something wrong.

Before you take anything apart have someone depress the clutch while you put a pry bar against the front crank pulley and have them release the clutch pedal and you apply a little pressure toward the rear of the car to see how much crankshaft end float you have. If you can visibly move the crank than that is probably the noise as the Spitfire uses only half of a crank thrust bearing and when it wares, it can fall out and give you excess end float which can make a cam chain make noise among other things.

If you change the chain and tensioner be sure to get a service manual as the Spitfire cam timing procedure is different then most engines.

Howard