Liberator, those "6217" heads are the bottle neck. You could spend some time porting them but still wouldn't end up with an ideal flowing port(s). I had a set on my stock '97' motor. I had them cut for big valves (2.02/1.60) spent a ton of time with the die-grinder, only to find when I fired my new 383 it sucked water through one of the intake valve pockets. There isn't enough material between the valve pockets and the water jackets to successfully install larger valves in those heads at least on the set that I had, it could have been a core shift deal, but it was a big waste of time and money. I then went with "World products torquers" with 2.02/1.60, and comparing the port design, the torquers have a much better (straighter flow) design than the "6217" head. The Torquer is a "stock replacement" so intake and exhaust port volumes are comparable, anyway the specs of that motor were: 9.3:1 compression, 208/[email protected] GMPP cam, mild bowl blend on the torquers, Edelbrock rpm intake and Holley 650cfm vac secondaries, stock exhaust. That engine in a 20' Crownline (3500 lb) would turn a 21mirage+ 5400rpm @ 62.4 GPS.
I upgraded that package with Vortec heads 2.02/1.60 valves, shaved to 60cc combustion chambers, thinner head gasket(.028 compressed) yielding 10.0:1, alot of time porting the exhaust ports, Edelbrock RPM air-gap, Holley 750 vac secondaries, Comp x-marine cam 224/[email protected], 1.6 roller rockers and Stainless marine exhaust. This motor will turn a 23Powertech to 5600rpm @ 67GPS. I actually installed the Stainless marine exhaust at the end of last season on the first motor and realistically didn't see any improvement, maybe 50rpm's or so. I'm sure they make a bigger difference with the better breathing motor I have now.
So short story long, invest in a good set of heads and worry about exhaust later. The Dart's you mentioned would probably be a good choice if they have the fast burn combustion chambers. Personally I was a little concerned to go with a 200cc intake runners, I was afraid of loosing torque in the 3000rpm area. Vortec's are a great head flow wise except they have to have valve spring pocket machine work done to run any decent size came (over .460 lift) and the exhaust ports are a little weak. Regardless, you will have to change the intake manifold from what you have now. Dart's or World products Sportsmans out of the box or Vortec's with machine work and a new intake about $1000 to $1200.

LMAC,
Good info, thanks. I was wondering what size runner to use. I figured 200cc might be too large. Any suggestions? I figure, if I can get the boat comfortably into the 60's with two guys on board, I'll be happy (For Now!). The Darts look like they'll be the way to go for me. I'm still pissed at myself for not doing it in the first place (moron). In a couple of years I plan on upgrading to a 24' or 25' boat. My next posting will be recommendations for that!

[QUOTE=TomZ] These hulls just don't have enough to run above that.
Tom
Virginia Beach[/QUOTE



Hope I don't shock you , but I had a 1988 221 Liberator from 93 to 2000. Three of those years it contained a 625hp 540 . No GPS back then but I could stand an 80mph speedo straight down. All in all the hull handled the power very well. You just had to respect it. The only times I let it loose was in calm conditions to a minor chop. When trimmed up and WFO it also liked just a little tab to stop chine walking
It was one hellava ride

I wasn't saying that the hull wasn't capable of doing the job... more so that the hull was going to be the limiting factor in trying to get speed out of it. That's why I'm looking for something else (and my wife agrees... sees no problem in spending $100k on the right boat... :eek ).

If I had the money to repower mine with that kind of power (and a drive that would handle it) and it didn't go 75+, I'd be freakin' pissed off!

It's actually a very good hull, and handles my speed (~60mph), very well. I think one of the big limiting factors is the weight. It's a heavy boat for it's size. I can go out in some pretty big waves, waves that would make my friend's Sea Ray puke!
I'll look into heads over the winter. Then I'll probably put my setup up for sale.
(# 14096217 heads with porting, Cast iron Z-28 intake, and Comp Cams guided roller tip lifters.)
I'll probably put the GLM manifolds on while I'm at it.

I meant Roller Tip rockers!

I'm a firm believer , if you put enough power to ANYTHING , you can make it fast



Well ok , maybe not a tug boat