What is acualy breaking when you say rebuilds 25 to 50 hours?? Are you talking catistrophic falure or broken spring , spun bearing? What do your bearings look like when you take them out? Are the parts blued or scored?

6000/6200 on a 572"..... Rod/Stroke ratio on the 572, I wouldn't go past 5700.....

300 oil temp is very high...

Droped,cracked valves, melted and cracked pistons, rod bearings..... Complete rebuilds 90% of the time. I agree with you all on the rpm's. I would like to see the power being made at 5500...but the motors "where built for that rpm range" And according to the dyno sheets that is where the motor is making power. I also agree that the oil temp is higher then I would like but the builder says it is ok??

Where are you all makeing your power? 5500?
Whats your water pressure? and temp?

The biggest question I think we would all like to know is what kind of motor life is everyone getting? (25-50-100-150+ hours) I wish I could post a poll.

Thanks again

I make peak power @ 5800 on the dyno and peak torque at 4600 but turn 5400-5600 rpms max. We spun them to 6K on the dyno just to see what kind of power it made.

If the motor is built right you should get 200-250 hrs on a mild boosted 572, not 50-80.... That's not even one season...

I run 100 degrees water temps and 210 oil temp. 15 lbs water pressure at cruise and about 22 WOT. I also installed small dumps to bleed off air pockets in the rear of the heads.

"Droped,cracked valves, melted and cracked pistons, rod bearings....." It sounds like you're having some problems with either detonation, lean fuel condition, fuel starvation (small fuel pumps). All the problems you're having sound like they are heat related and I'm going to guess you're running lean and/or the fuel system isn't adequate for the motors.

Also, if you're making power that high in the rpm range you probably have the wrong camshaft....

I agree with Panther. Try another builder.

I agree it sounds like fuel problems. That explaines the high oil temps also. What HP did the boat have originally ? tjek that pickups are big enough and go through entire fuelsystem. I have seen fuelpreassure senders that when installed into the fuellines almost blocked off the line.

We had 750's , We upgraded to 850's.

Fuel system=
Holly black pumps ran to high volume mec pumps on motor, The eletric pumps feed the mec pumps then to a Regulator 10 inches before the 850 carbs (new). All new fuel tanks and fuel lines. We run 7.5 fuel pressure. All lines are routed without any hard turns (kinks). The motors never act like thay are starving for fuel. Matter a fact the motors sound and act great....untill a issue. :(

We have looked at all pumping (rigging). I to lean tward the assambley.

How are your holley electric pumps rigged? Are they inline with the fuel line that goes to the mechanical pump or does it T in after the mechanical pump? What size fuel lines are you running?

I run 130 GPH Edlebrock pumps with Mallory 140 gph elec. pumps that have on at anything over 3500 rpms. 7-8 fuel psi no matter what.

Is your builder a marine shop? or auto?

Temp and RPM along with Boost seem to be the guys to go easy on..

..and a good marine buider as well with his cell # is a need.

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