572 GM conversion
 

I have a line on a pair of 572's from GM at a GREAT price. Obviously the carb and distributor need to be changed, but what else?

I have read hits and misses of things here, but is there a comprehensive list somewhere?

I am not committed, so just investagating....

Is this somethign WORTH doing? Thanks...

Re: 572 GM conversion
 

There Was a Post long ago on Hotboat. Reclearance rotating assy. Diff Camshaft And some Head work diff valves and such.
There have been a few put in boats. One in an Eliminator was documented in Hotboat Mag.

Re: 572 GM conversion
 

I think one of the offshoreonly boats went that root last year and had to change alot of stuff?

Re: 572 GM conversion
 

Ask BG1. He went that way a few years ago and broke one motor good. They are built for the street. TOO TIGHT for marine use. Need to clearance the mains, rods, pistons even maybe. Rebalance rotating assembly. Replace exhaust valves at a minimum. Might as well just buy the parts and build it from scratch.

Re: 572 GM conversion
 

that is what I thought it would take, but I am still learning, thanks...

Re: 572 GM conversion
 

Could you run them at typical automotive use temps if you run closed cooling?

Thus, the bearing clearance dimensions would not need to be changed.

Re: 572 GM conversion
 

Oh yeah, you want inconel exhaust values.

Re: 572 GM conversion
 

http://www.offshoreonly.com/forums/s...er#post1849577

oil bypass valves are different too

Re: 572 GM conversion
 

May need larger oil pan too.

Re: 572 GM conversion
 

Marine Power Is Working On Or Has Already Completed A Gm 572 Conversion You May Want To Talk To Someone Over There 985-386-2081
IN FACT IT WAS SHOWN AT THE MIAMI BOAT SHOW AND IS ON THE COVER OF HOT BOATS MAY ISSUE
620HP

Re: 572 GM conversion
 

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...............

Re: 572 GM conversion
 

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

BG1's story of woe.

Re: 572 GM conversion
 

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

Re: 572 GM conversion
 

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.