Its a G180W. you should see that on the block low down on left hand side near the front. Piazza,s had the 1949cc version very early on but were phased out in early 83. It is probably ex a gemini and the noise at start up probably isn't your chain. It is more likely to be all the cam gear as it gets quite busy in there and if a bit worn the oil bleeds back when switched off for any length of time. In any case if one of those chains is making a lot of noise it will be stuffed and should be replaced as tensioning isn't going to fix anything. The tensioner is fed by oil and it is ratchet out style, I suppose there is a chance the ratchet is stuffed or some one has latched it back by mistake. In that case it would be noisy all the time though. Unlike the G---z series engines I think these run a duplex chain..
Talk to the twin cam boys, not my area of expertise.
Ah - that looks like the "dark green" meanie - the ones that "flew".
Although I confess to confusion... I thought the "normal" early G180Ws where a lighter green.
And I have been wondering if the "flying greens" were G160W (and hence carby).
I have it all written somewhere...
Alas my "main reference" has been PC notes, and I haven't bothered recovering my pre-crash data. (After all, no-one else was interested...)
As Wedgy said, there should be a ~50mm high "G180" stamp protruding on the front LHS of the block (behind the alternator).
[Early G-series engines instead had a smaller G-stamp on the rear-right of the block underneath the original OHV and G-S SOHC distributor position which was replaced by a vent or oil separator for the DOHCs (but could still fit an OHV dizzy if not for the DOHC intake manifold).]
I'm pretty certain though that the greens did NOT have the ratchet-type cam tensioner. (I think ratchet started in the 2nd version of Gemini blue G180Ws & the Piazza G200Ws.)
The ratchet-type is identifiable by its triangular end as opposed to hex end (under the dizzy).
But hence possible start-up noise until the oil pressure builds.
And yes - duplex chains like all good engines. (Not knocking the Opel G-Zs, nor Trumpy Stag engines...)
I can't tell if the dizzy is a points or reluctor type. Not that it matters - IMO at any sign of trouble, keep its shaft gear but dump the rest and replace with the previously mentioned RG dizzy (early model RB Gemini dizzy guts in a normal Gemini or any G-Z engine points distributor).
The intake manifold looks like a typical 117-coupe; 5 injectors - the 5th acting as a "choke".
Presumably therefor a central upright oil filter (not forward-down as for Geminis), and probably the "steering box" sump (not rack & pinion as for Belletts & Geminis).
Thanks Wedgy and IZU, I was hoping someone would say it was the legendary 'dark green'... I have now joined (finally, thanks ISU) the twin cam group, so hopefully wont be bothering you too much. I'm away from the TR at the moment so cant confirm other details, although it's definitely a points model, but will confirm and post back results when I get back. Thanks again.