If all else fails then I think in front of the rad and in the bottom hose is the best option. To ensure it doesn't run dry, if it's in the top hose, then you would need a good head of water in the rad and they usually blow out any excess if you fill them too much.
So a little bit of an update, spent many evenings tidying up the best of wiring under the dash. This involve moving the extra fuse board I fitted last year (hot glued to the bulkhead) plus a couple of terminal blocks. Still looks a mess but is somewhat more ordered. Before:
Been faffing with the water Pump. Having had a look at my next door neighbour’s set up on his citroen traction I’ve decided to bin the thermostat housing and bypass circuit. The pump controller compensates for this by delivering 9 volts at 10 second pulses until operating temperature is reached. Going to give it a go and see what happens. Also going to mount the pump off the head, for it to run dry the water level would need to be 50% of the rad and the head completely dry - if that happens then I’ve already overheated and stopped.
buoyed on by my success at welding the stainless exhaust and so I didn’t have to change the wire in the welder I bought some 3mm stainless plate. i had played with the idea of just blocking off the bypass circuit hence the bolt.
I probably should have started by welding the simpler top plate first but I could wait to have a go at trying to get this rather near 90 stainless bend thats been lurking under my bench for longer than I can remember fitted. Used hot melt glue to hold it in place whilst measuring. The tubes are to make sure I can still reach the bolt heads and are only there for the mock up
So a bit of an update (i'll add some photos later). Progress has been slow as its mostly been cold and wet and drinking cider and watching telly has generally been more appealing...
1. Trigger wheel has been welded to the pulley, i only used 4x spot welds as i didn't want any heat distortion and it doesn't need to be particularly strongly secured (can't go anywhere). I did check with a micrometer thing and some wire stuck down a plug hole and tie wraps etc that TDC was exactly where the timing marks said it was - and it was. I then got the sensor in the right place and made up a triangulation mount bolted to the alternator mount - then painted it green to match my garden furniture. Wired this up to the data logger jobber.
2. Faffed around a lot with pipes. Though you can get 32mm adaptors for the pump it is cheaper to buy silicon hoses that reduce from 35mm to 32mm so i used them. Filled it up with water, watched it for a bit and only found one leak out of one of the gauge mounts, this was fixed by changing the copper washer it uses.
3. Got really annoyed with the alternator belt. Carefully measured it with a bit of cable and decided i needed a 700mm, this was woefully small, so ordered the 785 - which was too big, so ordered a 740 - which was too small, so ordered a 763 - which, well now waiting on a 750 to arrive in the post... Problem is that the pivot point is in the wrong place as it increases the length to the top pulley, not the crank so moving the alternator on its adjustment gives you about 12mm to play with and to get a belt on you need about 15mm of excess. 763mm is almost okay it's just a bit loose and i'm worried about it coming off. to fit a tighter one i'm going to have to fit the belt and then attach the alternator. I did try filling some of the casing off the alternator and hitting the engine mount with a hammer, but this extra movement in the arc just took it past its apex at made the belt looser again. grr.
4. turned on the ignition - which was a bit scary. New AFR gauge powered up, water pump beeped and started whirring. all very exciting, let it run for a bit then drained the rad and filled it up again, was very murky.
5. Started her up. Fan belt didn't come off. ran it until it got up to temperature and the fan/pump controller did its thing. The engine is definitely quieter without the mechanical water pump. Let it run for a bit then disconnected my exhaust powered vacuum engine breather thing, only to discover it seems to blow a bit rather than suck. have disconnected it for now. also my heat airlock hasn't cleared.
So plan is to wait for smaller fan belt to turn up and then take her for a drive around the block (after refitting the front seats). the new wideband AFR gauge is showing much more sensible numbers than the cheap narrowband one. Looks like i'm not a mile off, just a bit lean. Will probably do a few miles before making any major adjustments.
So 750mm is just a little too tight, alternator touches the block and it’s a faff to fit. 755mm I guess is what I need ideally but not seen one 10mm wide for sale yet, all seem to be 11mm, not sure how much of a difference that would make.