The 4A-GE engines to the 1985 design calendar year are known as "blue prime" versus the afterwards "pink top" engines, because the paint color around the valve covers is different, to show the various engine revision, employing distinctive port sizes, different airflow metering,

So for example if someone equipped a Silvertop oil pump over a Blacktop engine then the Blacktop’s timing belt pulley would want to generally be rotated half a tooth even more relative into the protrusion around the Silvertop oil pump. Pictured under could be the Blacktop pulley put on the top