Looks very nicely done - and has kept the entire Ariel transmission (including the primary chaincase) , which to me seems very unusual. (Additional pic below showing the BA box.)

I now await a list of Noriels that have kept the Ariel primary side and gearbox!
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SG

Might be worth checking what size the front wheel actually is - it's not unknown for the 20 to be changed to 19 in order to get a better selection of rubber.

SG

(With admin hat on - duplicate entry deleted. Please note that where an 'X' button can be seen in the line-up at upper right of a post this allows folk to delete the post themselves....) Rocker feed change was made a few years before the general introduction of alloy heads. I'd suspect probably to s...

There look to be some here and they appear to be pre-shaped so won't need compressing to fit.
https://www.feked.com/electrical/chargi ... em/dynamo/

SG

I think SRM are quite keen on doing 'colisbro' inserts for worn valve guides, possibly a few more folks are going down that route now as well 'cos SRM have been doing it for ages. I think I've seen an alloy head that had a cast-iron valve guide in it but I've never come across anyone who's thought i...

I've never seen anything about any special coating on a Leader/Arrow barrel - they're just 'standard' caste iron!

SG

Ian In your situation probably best to take the headlight out first (the single screw at the top will loosen the retaining clip and the headlight will come off with the rim - might need a bit of gentle persuasion, but the rim comes off from the top first). You can then get a fairly good look at the ...

My 'early' (1940s and early 1950s) covers have the oil hole and the groove. I seem to remember my '56 cover also having the oil hole but I might be mistaken (it's assembled on the crankcases at the mo' and I'm not taking it off to check - however there's also a chance that I might have drilled it to...

By the late '40s the drive-side mainshaft number for all models seems to have had a 35 number, so possibly the change was standardise the mainshaft?

SG

Just for completeness (or maybe confusion!) Here are some pics of a NOS timing cover I've got that came from Writers. No oil hole, and no drilling for one - but the bush does have a groove. The spares book lists these as being supplied 'with bush, oil delivery pipe, pressure valve and...elbow union'...