rob vanharten

Any reason not to buy a boat with a counter rotating 572 bbc? It is required on this boat due to an arneson drive. I don't have a good reason but it feels like a red flag to me, but as I understand it the only difference is a the cam gear setup, starter, and firing order. Do they sound any different running? Probably a stupid question but it just seems so unnatural.

Team Archer

A lot of old boats ran opposite rotation motors. Most all twin engine inboard boats ran them. The Gentry 4 engine cat had 2 engines run LH and 2 engines run RH they were tied together thru a gear box 2 engines to 1 prop they ran great.

dereknkathy

the one possible issue is the cam itself. it isn't a standard off the shelf opp rotation 350 horse cam, so it would probably have to be custom ground. the engine torques will cancel each other out, which is a good thing.

ezstriper

been running one for years, they way its reversed makes a difference, in old mark IV BB's they ran a gear to gear so cam/dist run std, works fine, with Gen VI there is no room(they say) for this, they put a reverse cut gear on cam and dist, issue is it now reverse's the load on the dist, std will dist will eat themselves up in no time...mine ate about 5 before figured out WTF. As of now they make a GM EST that is modded with a extra bearing the top and works fine.

dereknkathy

I have a reverse 2 piece crank with a gear, not sprocket on it. The reverse motor in my hatteras also has standard dist rotation. So I am sure gear drive works on rev rotation Mk 4's.

ezstriper

all dist's have to run std rotation as they drive the oil pump..

NautiSouth

In a reverse rotation application, the standard rod pin oil breakout location would be close to where the rod bearing is supporting combustion load, and would reduce oil flow to the rod bearing. Are the crankshaft oil drillings different in reverse rotation engines?

dereknkathy

the same crank. same oil drillings.

NautiSouth

Well that's less than ideal. Glad to hear it works, though

ezstriper

some have experimented with flipping the pistons around(notch to the rear) seen both ways, just tore down a merc 5.7 and they were swapped, but all the cranks/rods/pistons are the same, they do make special rear main and front cover seals that are reversed