[shommel]

i pulled a sparkplug and it was fouled with oil whats the reason(or reasons) for this?

[Ivy66GT]

Oil on the tip of the plug comes either from leaky rings or more likely by oil dribbling down the valve stem. The 289 heads didn't have a true valve guide, just a hole bored in the cast iron. If you haven't had them sleeved then likely that is your problem. Old, stiff and worn valve stem seals will allow oil through even if the guide clearance is OK.