Kidnova

To start with....Replace or marinize carb. Marine alt., starter, ignition. Head gaskets. Brass freeze plugs. Bigger pan. Change oil bypass valves in block (remove center valve). Proper/large oil cooler. Larger than "stock" oil lines. I'd have rmbuilder check cam specs to see if there would be a water sucking problem. That's a short list just off the top of my head.......

I've been running a ZZ502/502 for 4 seasons now and have +,- 140 trouble free hours on it. I've put about 30-35 hours on this season. I generally change the oil every 20 hrs or so, but let that go this year (I feel guilty about that). I've added 1/2 qt. of oil to the engine so far this season to keep it to the full line. I've been in a few local poker runs where I've gone 25 miles at just about WOT with no issues. GM says max RPM is 5800. I have it propped for around 5200, which is where GM says it makes max hp. Two things I did not do but I wish I had done for peace of mind is larger pan and lines. And inconel exhaust valves.

Not to argue with those more knowledgeable than me...but I was told that the stainless steel valves would be plenty safe to stay with as long as I did not constantly beat the chit out of the engine. Was also told in relation to Merc marine engines (black ones); Merc uses the same short blocks that GM/Chevy uses in their vehicles. And clearances should not be an issue unless you plan to run hard and or spin high RPM's frequently.

Considering the good experience I've had with the ZZ502, if I was in the market for a new 620 hp engine I would definitely consider the GM 572/620.

Just a few thoughts from a newbie...............

Airpacker

http://www.offshoreonly.com/forums/s...72+crate+motor

BG1's story of woe.

Joe

There's a local guy here in Houston who bought two TG's w/ those engine pkgs, I believe. One of his friends, who is a friend of mine, is Les Ellard aka "Bunky". Les had them in his Gun as well (which he has sense sold, "Smo King" was the name of the boat).

You're welcome to e-mail me if you'd like Les's #. I'm sure he wouldn't mind talking to you about his experience w/ the 572's.
Joe

ROTAX454

Some time ago Bob Leach at Eliminator had a customer that wanted to try a pair of those 572/620 crate motors. Check with him on the long term events. First reaction was very good with minimal changes to the motors for marine use. As Kidnova wrote in his post, some things are necessary. But at minimal cost.