Roger King

Probably a Chapman weight (cost?) saving thing. It's not good for an engine to run sans thermostat under normal road use, but the swirlpot probably has something to do with it.

The Ford part number we used to use for this is 6814635. I have no idea if it is still available but it may be the same part you have illustrated.

The easiest solution seems to be to buy a pre-1982 7, have it fully rebuilt, and then you are ULEZ exempt.

Yes, it is. It just seems an odd exception. Please don't think I'm complaining!

Bizarrely, my 1958 Frogeye is ULEZ exempt. Go figure.

Personally, I'd limit a std BDR to 7000rpm, but that would be if the crankshaft had been tufftrided and best material bearings, etc fitted. Unless you're racing, I'd limit even a tweaked version to 7200rpm, bearing in mind that it has a standard crank and rods, flywheel, etc. For competition use we have taken them to 7500rpm, but I assume you want it to last. A steel bottom end is a different proposition, but will cost.

You have to remove the cam cover first. You will then find a small vertical steel pin directly above the rear seal (one for the inlet, one for the exhaust). These engage in a groove in the seal carrier and prevent it from just dropping out. Pull these pins vertically out and the seal carriers should then theoretically just pull out with a pair of pliers gripping the spigot that protrudes from each carrier. The seal is just an 'O' ring, but sometimes you find that the previous builder has used silicone sealant as well, in which case they may be difficult to pull out. I have also seen them with the sealant, but no locating pins. In theory it is a quick and easy job.

Gobsmacked.

I can't help with the origin of your engine, although I am not aware that Cosworth ever supplied the BDR in anything but kit form, so maybe that was what was meant. I've bought numerous BDR kits from them in the past so I suppose I could describe them as having come from Cosworth. But steel caps may have been fitted for a number of reasons - second hand block that had lost the original caps, ignorance of the capability of the standard caps, an intention to tune further in the future, etc. I would be amazed if it had steel pistons so I'm sure as I can be that they meant forged as you say. Steel or iron pistons did exist in the early days of the internal combustion engine, but I'm not aware of anything current using them. Cosworth supplied the pistons as part of the BDR kit and they were most definitely forgings. Basically, the kit contained all you needed except the bottom end of the engine (mainly block, crank, rods, bearings, sump, oil pump, etc. The idea was that it was a conversion kit for an existing Crossflow.

Look like standard rods (probably 711m), but polished on the flanks. And with better bolts fitted (Cosworth, ARP, can't be certain)

Simple, they're stronger, but not generally necessary on a 711m or AX block because the originals are almost bullet proof. On second thoughts, maybe a good idea on a turbo or super charged engine running a lot of boost. Provided they have been done properly though, I can't see any actual down side to them. What does seem odd here is that the crankshaft appears to be standard and any engine with one of those ain't going to need steel caps.

The "outlet" on the water pump is actually an inlet. It sucks water down from the header tank and back into the system. There is no significant difference between connecting the hose here and connecting it to a T-piece on the bottom hose. The header tank is fed from the small pipe on top of the thermostat housing.

It's cast iron.

If it's a real BDR then the block is iron. There's very little to be gained in stiffness with a cast sump on these, but a lot to lose in terms of vulnerability. Go steel.

You will only get a small amount out of the sump, so you will have to drain the tank separately. If you don't do this it will likely drain down very slowly via the oil pump and make a mess.

It's highly unlikely that this will render the crank unserviceable. However, it is ESSENTIAL that any burrs or high spots are removed before fitting the sleeve; a Dremel or similar may be needed. Depending on the final result it may be advisable to fit the sleeve with a little Loctite retainer, then the bearing can go in as normal.

I don't know which exact pump you have, but if you take the end plate off, thoroughly degrease and then use an anaerobic sealant in addition to the 'O' ring (if fitted) you should be in business. I don't recommend using a silicone sealant because you might just be unlucky enough for a bit to break off and get into the oilways, although the filter should catch it. There are plenty of such sealants available. I use Loctite 510.

If it runs on pump jets but not mains or idles I suggest you start with the carbs - float levels, blockages, etc. Also check fuel delivery.

Just to add that a dry sump BDR only needs the breather from the cam cover. The one in the block should be plugged. The cam cover breather feeds to the top of the oil tank (thus returning any oil to the system) and then you have a small catch tank fed from the top of the oil tank.

If you have the head off it would be madness not to fit unleaded exhaust seats at the same time. I can't give you a price since I stopped building engine twenty years ago, but it shouldn't be a huge expense. Just make sure the job is done by someone who knows what they are doing.

From Caterham, no they didn't have hardened seats.

Firstly, are you doing the compression test with a warm engine, the throttle held fully open and the ignition disconnected? That is the correct way to do it. 15psi is about the variation you can accept, so yes, four is too low. Before you do anything, take the plugs out and squirt a little engine oil into each cylinder, crank it over and try the test again. If no. 4 has improved significantly, it is more likely to be rings than valves. Ideally you should also use a leakage tester which will not only give you a reading, but you will also be able to hear if the leakage is coming out of the crankcase breather, the inlet manifold, or the exhaust, thus identifying the source of the leak for certain.

If it's standard spec, around 180psi, but as already stated, consistency is the key because gauges vary so much.

Basically, it's the same kit as used on a Crossflow, so fairly easy to sort.

Can't tell from the photo, but it's likely that the engine has been fitted with a toothed trigger wheel and sensor. Once that's done it's a relatively simple matter to fit an aftermarket ECU and a coil pack. In theory, it could even be that a distributor is being used to trigger the ECU but that would be largely pointless (yes, yes, I know, it's a terrible pun) because you'd lose all the precision of the ECU timing control.