Spotted your post and reckoned I could chuck in a bit of useful info. So, the timing chain and sprockets that you get with the crate engine ZZ502, right? They're actually machined in what you'd call a 'retarded' config compared to the usual timing setups. This means the camshaft timing's done a bit later in the engine cycle. It's not odd for performance engines like the ZZ502, this, as it can give the engine's performance a bit of a boost, especially with the power output when you're pushing higher RPMs.