So for example if somebody fitted a Silvertop oil pump on the Blacktop engine then the Blacktop’s timing belt pulley would need to be rotated half a tooth additional relative on the protrusion on the Silvertop oil pump. Pictured below may be the Blacktop pulley placed on the top from https://mariohezpa.bloggosite.com/38002641/the-basic-principles-of-toyota-4age-blacktop-engine-for-sale