[The cap'n]

Let's think about this a bit. Components expand with heat, and chains, even the whole engine share this characteristic. That chain's gonna stretch and the engine is actually gonna "grow" a bit wider. Not much, but it is measurable. The function of the chain tensioner is to keep tension on the chain, which gains slack as the engine warms up and as the chain wheels wear. That's why we have the chain support wheels on a pivoted arm. I figure the closest the chain guard is ever going to be to the body of the tensioner is going to be when it's freshly installed in a cold engine. Note, I "could" be wrong on this, but I think it's a pretty safe conclusion. I agree there may even be some slight extension of the shaft after turning the crankshaft a dozen times or so, but it might not be easily observed. In this case, I think I might be inclined to install the guard as close to the tip of the shaft as is practical and go with it.

The Cap'n