540 cu in Merlin III built for a high performance Jet Boat

The engine came to us because it had dropped a valve

The head of the dropped valve sitting on the piston once the head was lifted. 

The cause of the failure was incorrectly fitted roller rockers.

From this picture you can see the roller pinion was fitted upside down. 

Start up

New springs, retainers & 10 deg jumbo locks. 

Complete set of new severe duty stainless valves. 

Heads fully ported & polished. 

Ports modified, CC'ed & flow tested. 

New 2 " Phenolic spacer & intake manifold modifications. 

New Valves 

Chambers modified & CC'ed. Heads decked to suit. 

Short block assembled with new forged pistons

New roller lifters