Boost,

I don’t know if it would cause more problems than it solved, but I could see upper valve stem guides incorporated into that rocker arm plate.

Thanks. Brad.

Awesome Videos
 

Thanks Brad for posting. From my vantage point as an ME from Dayton some great insight on Mechanical Engineering at the highest level. He even touches on the metallurgical side of the demonstration, which is where my career path lies. Very very cool.

Without going down a rabbit hole to nowhere.
10,000rpm for a 4sec pass
7500rpm for 2 hours.
You tell me what's harder on equipment. Its not so much the stability of the rocker arms (everybody basically runs TnD or some variant of them). As JD said above, its the harmonics of the whole package. Surfaced cleavers coming in and out the water, solid everything, so on and so forth create vibrations and harmonics that tear valve trains apart- especially at 7500. I had Richard Iskedarian tell me once that a bad harmonic in an engine can wipe a set of springs out in one dyno pull. Real Pro Stock guys have 3 or 4 different sets of springs for every engine. They run the ones that are "happy". Real race boat stuff is so far from pleasure boat stuff its insane. And then? You run the poor thing just as hard as you can for 1-2 hours. Our sport is one of the toughest there is on equipment. Period. Back when we ran 160 miles, you sandbagged as much as you could to save the equipment. These days its WOT flag to flag. Husker knows first hand how a 2.5EFI could tear its self apart at 8000 but live all summer long on a pleasure boat. And they dont even have valve springs lol.
Plus, people never realize (particularly car guys) boats are in 4th gear going up hill all day. No coasting. No shifting. Your car shifts way before 3500. 3500 is an easy cruise for most of us.

I was told by one of the 3 QC4V in the US that BBC wasn`t designed for marine use..the QC4V engines were designed for marine use from the ground up.
400 hrs on a 1100 is no problem.
Makes sense

5o years of racing
 

I know its an old thread and I'm a Newbie to the site but not to racing and its 2 things. Inferior parts and fatigue. That reaching to the smaller parts which is valve vtrain. Billy God old has spent. Any many hours when he was at ComP as researching this. Longer length rods apply more theust to the sides of the block and pistons tend to rock more because the shorter the rod the faster the piston travels within the same stroke. You can almost build a bulletproof engine, but it must be torn down often to refresh and replace parts.

A pro Mod in 20 runs is 100 seconds. Replace 1/4 of engine parts to prevent ent catastrophic failure.