When should these be replaced, at what hour of normal use? 85% at 3,500 and 15% WOT.

thanks
Shawn

250-300 hours. Check the trunnions for play or notchy bearings. If you replace spend a couple extra buck and go with the Comp Cams stainless rockers. They are easier on the valve train.

Some guys are buying the Jesel Sportsman rockers but they are really pricey. If I had an extra 800 bucks a motor I might buy them but so far I haven't had that kind of extra boat-motor cash.

Or.......you could spend about the same money as new cranes and get the Comp Pro Magnum roller rockers! They are made from chrome molly steel with actually less weight over the valve than the aluminum cranes, which is why they are easier on the valve train. The Comps are also going to be stronger than the aluminum ones that you currently have!

I think they last more than 250 hours. Inspection is very important in looking at parts. Check the roller tip. It should roll easy but not be loose. Feel for any bump on turning it. A bump indicates a flat spot on a race or bearing. Do the same on the larger main bearing. Look under the bootom side where tip push rod sets. Wear should be even. Look for small cracks begining.

Usually when they go bad, you can hear them or the engine looses power. I know people who use the same ones over & over. That does not make it right but, if peace of mind & $ is OK, change them. I see a lot of good parts disposed when not needed.

I do not see how a different rocker can make it any easier on the valve train. That is controlled by the cam ramps, & the spring pressure applied to the ramps. Most all valve train damage is from not enough or in a few cases, too much spring presssure.