Model A - Primary chain

 Today I have fitted and tensioned a new primary chain, which for the record has 80 pitches. If you recall, that is a 23 tooth engine sprocket:

The 23 tooth sprocket I've fitted is the largest one Ariel offered in 1930:

This appears to correspond with an 80 pitch primary chain, though I'm sure 79 pitches would fit as the chain is nearing the end of the adjustment.

A 79 pitch chain would need a half-link which I believe are available from Simply Bearings. I might investigate that, but I don't fancy having two spring links in the chain.