what would cause guide plate to brake? its a 502 and does have alot of hours. looks like just sheared off. the studs are tite and was at idle when it happened. it was a comp cam guide plate.

check for a really bad valve guide. i am dealing with this issue as we speak. iron Dart small block heads. 3 or 4 years old. mebbe 200 hours. put on head, tightened rockers onto pushrods. one fell over on it's side. changed rocker and pushrod, same thing. tried to stand it up by hand, valve moved 1/8th inch or more sideways. pulled head and valves. 1/4 inch of side-side play. all 7 other valves a couple thousandths tops.

will check that thanks. will let you know what i come up with

ab,
Better take a look at the lifter too if you can. There really is not a lot of stress on guideplates so I would have to say that something else caused it to break.

Bill Koustenis
Advanced Automotive Machine
Waldorf Md