There's a youtube series of a chap who recently rebuilt a mk3 engine which is well worth a watch as a guide/refresher on what to do.  Red fox classics I think it is.

I picked up an unknown Spitfire Mk. 3 engine in the winter, I haven't really looked into its condition yet other than seeing the plugs were oil fouled (evenly, at least), but the crank end float feels okay so hoping its rebuildable. It also came with a Spitfire Mk. 4 3-rail gearbox, which I think I can make work... There are a few caveats, but I have worked most of it out in my head already. No doubt I'll be asking lots of questions to confirm my ideas are sound as a lot of it is unfamiliar territory for me. Thanks for the offer of engines, will keep you in mind if what I've bought ends up being bad.

LD performance with a genuine bosch 4.9 I wish it was a "dial" gauge, but instead has big red led numbers that change rather fast.... I do have 2xcolortunes somewhere, I will dig them out.  I have also discovered there are several different piston weights. At least it seems to be the diaphragm clamp ring that varies. I might play with adding weight, but I will see what happens with the 1360 bits. 

What engine are you wanting to end up with? We have a small crank Spit 1300 that runs well apart from needing exhaust valve seats. Also a 1360 block, crank, head etc needing rebuild but still on original sizes. The latter is free to a good home!

Interesting, though I’m a bit wary of your wideband. 9 at idle should be black smoking, mid-firing, hunting and surging rich. Likewise, it should be hitching and hesitating, even falling on its face well before 20! Which wideband is it and what are you using to read it with? At idle, you could use a colour tune plug as a sanity check. Change from orange to blue occurs mid 14s

Didn't realise your in Wick, spent a lot of my childhood in Melvich, such a stunning part of Scotland. We head up quite often to the NC500, the weather has brought out a lot more unusual cars ( Porsche club seem to be up every weekend ). My favourite so far was an old boy towing his mint Morgan behind an equality trick Defender, apparently the wife only enjoyed short journeys in the Morgan

I popped a wideband senson into the exhaust on Saturday.  I had teh carbs set up according to the "book" using the lifting pins. Balanced with a proper crypton synchometer (the best bit of balancing kit for twin carbs) The AFR at idle is around 9! Took it for a drive, and off idle/low revs it was just into double figures. Get to 3500 and it was hitting 20! So it really is out by a country mile, but drives "OK"  Took a file to the needles, taking great care to match "intensity" and number of strokes. Better, but still miles off. A glance through the needle charts suggests the 6J needle is almost the richest available, though the original 7B (vit 1600) is a tad richer in a mid range, not by much. So certainly would not be enough.  I am "borrowing" 2 carbs from a 1360 which have the heavier pistons, though I have no idea if they are the same as the original 1600 ones. I will try them with the light springs fitted to my carbs, see what happens. After that I will see if I can scrounge/borrow some later "medium" springs to try (if anybody has some later springs, mk2 engine onwards, kicking about and not needed for a few weeks.... please let me know)

Good luck!

Yes, very elegant. Good looking car. Yes, I think so. Though our XJ6 specialist @PaulAA may be able to confirm or deny. Looks to be sat a bit higher than normal but maybe due to being parked on sloping ground.

Staying in Wick, Caithness I often see interesting vehicles making their way through (often foreign cars unfamiliar to me) but on occasion I see ones actually parked, thereby providing a photo opportunity ….. First up today is a Jaguar XJ coupé, a rather elegant design I think? Are the wheels off a series 3 whereas with overriders this is a series 2?   Ian