Cam size with factory exhaust
 

I have a 454 and was wondering what some of you folks have used for cams with factory exhaust. I had installed a 262 hyd/flat tappet extreme marine compcam in my motor and it was ok, but I happened to drop an exhaust valve and we all know what happens then. I really want to move to a hyd/roller 284 marine, but wasnt sure about the factory 4 inch exhaust. Thanks for anyones help.

That's probably too much cam for stock exhaust. Was it thru-hull exhaust? That helps some, but the stock manifolds and risers still put the water stream too close to the exhaust ports to run much overlap on the cam. There are many threads addressing this issue if you do a search over on the Technical forum. Furthermore, since you dropped an exhaust valve, I would verify that your risers were not leaking water back into the engine, especially if it was the #7 or #8 cylinder at the back of the engine. Water reversion onto a red hot exhaust valve is the root cause of many failures in marine engines, even with stock cams.