Yes I am not going to risk it. Both motors are coming out this Saturday, and going to JimV for inspection. Then both motors are getting the crane 741 cams, new hydraulic roller lifters, new push rods, and new valve springs. While they are there Jim is going to be giving both sets of heads some custom work also. I hope to be creeping up on the 600hp mark.

I was told the boat went 75 mph on gps with the current motor setup. With almost an extra 100 hp a side, what do you think my speeds will look like, with proper prop change of course?

its takes alot of power increase to see more noticle speed out of a boat, but props chamge it alot more then hp changes.

75 on GPS with basically 500's is pretty optimistic. With 420HP per side these were 60-63mph boats. I'd say with merc 500's, maybe, MAYBE 70 with a tailwind, no fuel, and one person on board. 600HP mills, i think then you will see 75 honest mph out of that hull.

Good To Hear Your Tearing It Down Rob! Your Doing The Right Thing.
I Really Feel For You. Looking At This Situation From A "glass Half Empty" Perspective.....at Least It Happen At The End Of The Season And Not In The Beginning. You've Got All Winter To Fix It Right And You'll Be Good To Go In The Spring!
Let Us Know What The Failure Was When You Find It. I Kind Of Scanned Over All The Post So I Dont Know If You Had Already Located The Issue Or Not. I Suspect You'll Either Find A Lobe That's Destroyed And/or A Lifter With A Torn Up Or Missing Wheel. Good Luck To You! Mark

nice

Today is the day the motors are coming out. Before the weekend is done they will be sittong in JimV's shop. So this new idea has been floating aroud my head of having Jim either go crazy with my iron heads or going with some dart pro 1's or the afr heads. I would love to be at 600 hp or even a touch more. Here is the quick list on what these motors have/will have.
HP 500 base motors
9.5 cr
bigger oil pans (not sure which ones's)
crane 741
hyrdraulic roller lifters
crane 1.7 rockers
dart hp 500 intake
holley hp 500 carb
stainless marine long risers exhaust system's
now what can be done with stock heads and Jim's work versus aftermarket one's. I have searched many threads on here and have seen this package make 600-640hp with lower cr. Some day I would like to run m-3 prochargers on these and make 750-800hp, but for right now I would like to see 600hp when they come back out of the shop. I guess I am looking for any comments or information on what we be the best way to go regarding the heads and the build as a hole.

Of course if you can swing some new aluminum heads, that would be the way to go. Especially, if you have plans for a blower in the future. Aluminum heads will allow for a little more compression, as they dissapate combustion chamber heat better. I would touch base with Jim on AFR Vs. Dart, etc. While some heads flow better on the bench, there are issues with some of them when it comes to design and install issues. I would go with his recommendation and what he has experiance using/working with.

As for the blowers, my personal preferance would be going with a roots blower. Something like a 8-71. prochargers are nice, but too many people i know who run them, have issues. I guess there is a reason if you look in the classifieds, majority of all the 700-1000+ HP motors are using roots blowers. they just flat out work in a boat. But, keep in mind, your drives will not last but a few weekends if you do this!!! Adding some 8-71's to your 600HP mills, will put you in the 750-800HP range. Unless you are running ssm drives, or arnesons, i wouldnt do it.

With 600 per side, your boat should be running upper 70's. And still gonna have to baby them drives.

Spent the morning at Jim's shop, what a great great guy. He took the motor in question apart right in front of me so we could determine the problem. The lifter on the number two exhaust manifold was junk. Large flat spots on the roller, and needle bearings gone. Cam lobe took a little beating also. Anyways Jim will be tearing down, checking crank and everything else just to be sure. Then all the new parts He was just a awesome guy and answered all of my questions. Sounds like 600hp will not be out of reach. It was a good day, and I feel like I am in very good hands!

Its always good to actually find a problem, rather than mystery ones in my opinion. Im sure Jim will have you up and running so next season you'll be running and enjoying the boat!