Hi, I new to this so please bear with me, Im in the final stages of rebuilding a N/A YB engine of dubious pedigree, Ive just fitted the cams and have noticed that the inlet cam pully is loose (?) ie, it rocks on the keyway, on closer inspection Ive found that the inlet woodruff key has a step and only measures 3.75mm wearas the exhaust key is about 5mm. now at first I thought it had simply worn and needs replacing but Ive found a piece of steel shim that was fitted to fill the hole, but I think on the wrong side!!
So my question is... was it originally built by a moron who should have sorted it out properly, or was it a clever (and cheap) way of altering the cam timing instead of using vernier pullys? has anyone heard of this before? if its a known mod perhaps I should re assemble it with the shim in place

Cheers