Clive

That expansion tank does pressurise, it is the same a dolomite and countless others from the same era. Ideally replace the others with higher pressure caps or seal them. It may be worth changing things a bit. It may be possible to get rid of the thermostat housing one by using a std herald type? At the moment I think the big hose from that is acting a a huge bypass, far too large. In fact, I am head scratching about what would be best.

Yes, canleys (and probably others) keep oversize circlips. Buy plenty, add them one at a time until they are tight. Not sure how many thicknesses are available, it used to be a few.

Ah, that may be down to float levels. Looks like fuel level is too high. And surprised it isn't coming out from the overflow tubes on the top of the float chambers. If you are able I would try spacing the pump off the block 3mm (and maybe 5mm) to see if that fixes the issue. Assuming the needle valves are not ridged/worn, which you say they are not.

No pic attached. But out of the overflows, yes.

Is it a new (ish) fuel pump? They have a reputation for producing too high a pressure and overcoming the float valves. It is possible to use a pressure regulator set to 2psi, or I heard a stack of pump gaskets a few mm thick will do the trick (not tried that. But I would probbaly make a spacer from ali or steel to try)

The cast twin outlet manifold will only fit with twin carbs. (I tried, really tried, to get one to fit with a single carb. And failed.)

Did your dad smoke a pipe? Using the power of google image search.... https://rebornpipes.com/tag/kleen-reem-pipe-reamers/

Not sure you have joined the right forum. We are for Triumph cars.

https://www.ebay.co.uk/itm/254656405760 Problem solved. Assuming it is genuine Codan stuff, which is probable.

It is possible to fit a solid UJ without cutting etc, or at least I have a few times. However, one I fitted had a huge amount of play fresh out of the box, it was dreadful. So if you go this route, find a reputable supplier. I thing the spline diameter is 9/16, there are several different sizes. The good ones I have used have been excellent. The poly kit is a good solution, I have done that on 2 cars, one was on for donkeys years/daily use with no issues, but don't take that as a guarantee.

For batteries I have been using Halfords HB063, but I have a tradecard so price is good. 063 batteries fit, but the terminals are near teh bulkhead, still the correct way round so battery leads fit. In addition, terminals near the bulkhead mean they are away from the battery clamp. Alternators are a bit more efficient, and charge a battery faster. But if the dynamo is working, I would leave it. To fit an alternator teh first issue is finding a quality item, there are so many poor quality repro or "recon" ones sold (record for me was a new Lucas recon lasting about 150 miles) Ideally a later spitfire mounting bracketry. The control box is no longer used. The F+WL wires need joining, the earth wire is unused, all the other wires need connecting together.

Try jacking the car up under the diff, as central as possible. Just get the wheels off the ground. Then check the front springs are equal. Next, do the same jacking the car under the front crossmember dead central. Check the rear. Often the issue is at the othetr end of the car. Dio make sure all that is done of perfectly level ground. Ideally measure to chassis points rather than body.

Why not saw your existing manifold, chopping the inlet part off? That seems to have been the "usual" solution when fitting twin carbs to a 1200 herald. And the manifolds are much easier to source than the spitfire type. Or get the manifold machined flat?

You may be better off contacting Tim direct. I expect he has any spares.

Spline sizes seem to be common across all sorts. So a Ford T9 box can use a TR7 clutch plate, and there is a ford escort plate that fits the single rail Triumph boxes ( you can use the cover too if the flywheel is redrilled) But even more bizarre is that Rover driveshafts slot perfectly into Subaru CV joints (as used on my spitfire) but again Ford, mazda and others use the same pattern.