1967 18 classic

[ethyl]

When I purcased this boat it had a 350 chevy and older style mercruiser outdrive. The engine obviously had been modified as it had a high lift Comp Cams cam, Crane roller rockers, forged TRW aluminum pistons, Edlebrock torker intake and a 750 double pump Holley carb.I know these things because I was running Her about 4600 rpm@ close to 67 mph when I thought I had thrown a rod so I put Her back on the trailer and pulled the mill out for dismantling at a local shop. Evidently the cooling jackets developed cracks and I was getting water in the starboard bank which bent several pushrods and caused #6 to jump of of the lifter which must also have broken the rocker keeper. Anyway I am having it rebuilt and wondered if I should go with aluminum cooling jackets or iron. What does anyone know about Moore exhaust products out of California. Is the 750 to much carb? Thank, Ethyl

[wagspe208]

Which "cooling jackets".
How did this cause pushord issues? Are you sure proper valve spring installation/ coil bind was addressed?
Me thinks something else is going on.
Wags

[mphatc]

Allow me to suggest that you do a bit more investigating before you just assume that the exhaust manifolds cracked . .
High lift long duration cams are not often the matched for marine applications . . to much duration might cause you to draw water in through the exhaust ports . . reversion . . .
. . but . . .
to bend pushrods something else had to happen . . possibly something that caused valves and pistons to meet . . :confused::boggled:
one could theorize a bunch of scenarios . . like . . . .
water getting in from a cracked exhaust manifold, ( BTDT) and hammering a rod bearing through hydrolock . . causing the ultimate failure, but this would cause an immediatley noticable poor running situation . .with enough time to cut the throttle. This happend to me last fall resulting in two tuliped intake valves, but no piston and valve contact . .
I don't understand the bent push rods . . . ????
Mario L.

[maddad]

If the rocker studs weren't changed from press in to threaded, they may have been pushed out, causing all the damage.