Thanks for that Bob, unfortunately its not a 3T, ive been advised it has 650cc on the timing cover!!
But as there are no crankcases, can you be sure that the timing cover actually belongs with any of the other parts?
'650' as far as I know was never used on an original Triumph timing cover?
I would expect the Triumph timing cover to have a triangular 'patent plate' (or at least the three small rivet holes if the plate is gone)?
I must agree with Bob 33d6 from the description of the crankshaft arrangement you have given that it is most likely to be a 3T 350 if it is actually a Triumph engine?
Even the pre-war model 6/1 650 Triumph twin had split big ends and (steel rods?) with a different flywheel arrangement I think?
This is where some photos of the parts would be very useful. Is there any chance that you can either post some up, or email them to Vintagebike?