SONICUSA Sonic I would like to hear a little more info on these valve spring failures. GM has been running beehives since 98 in V6 motor with only a very small failure rate. A marine motor is different that a street or 1/4 mile motor. For you to break this many springs, IMO something was not done or checked for clearance. I have run a set of #26120 BBC spring in my motor for 4 years, no failures from the springs. I have had 2 broken rocker shafts. Auto cross and roadracing.
Where are the springs broken? Top, Bottom or in the middle? What cam shaft are you running? What rocker arm ratio are you running? Has the oiling system for the heads been improved?
From what was said these boat motors where never over 4,500 rpms and dynoed at 6,000. I run a hydro roller camshaft and crane hydro lifters. The rockers are ERSONS. Push rods are hollow 5/16". I have run this motor on a chassic dyno and motor dyno. 5,800 rpms the valves float. I have pushed the motor to 6,200 rpms to see how much HP is lost in the last 400 rpms. What has saved my motor is flooded heads with the oiling filling the head to the
oil drains out of the pushrod hole in the intake. The other thing is my lash is only .015" plunger depth. My motor block and heads are Aluminum. This lash is gone when the motor is hot.
If your valve spring where blue at the bottom or snapped at the bottom, they where overheated and lack of cooling killed the springs. I have hear that Comp had some bad wire, couple years ago and springs breaking from spring binding at high rpms. I have a guy behind my house running beehives and turning 7,200 rpms in an LS2 motor at 7,400 rpms the valve train goes bad fast. 2 years and 30+ races on the east coast no failures. Again a different motor but heavy abuse.
I agree about having only 1 spring for control of the valve is not the best thing but if you know the limits of these springs and have good lube to keep them cool, there should be no failures. If you are not happy with Comp beehives, you might have looked at PAC springs. They have a spring with a higher ratio, 420 instead of 377 open rate. 20 more on seat pressure.
My last question is are you running spray bars in the valve covers? I have question Comps Tech guys over the years and not been happy with their info on some issues and learned by failures. You have two 468 motor with top of the line parts. Something is not adding up with failure. Would like the specs on your motors, PLEASE. Rick L.