That is a one time only circumstance.

I know i know! Just saying it can happen...

When I bought my 2000 fountain 2 years ago, the previous owner had preached how he had never cracked the motors and at exactly 450 they were perfect!!! I was a little guilty of buyer excitement. Well my first full day on the boat i dropped a exhaust valve into the cylinder. So now roughly 10 or 12 grand ( I could never bring myself to look at all the extra parts receipts, oh yah, and then there was the new set of headers $$) later my newly rebuilt engine is ready for another 450 hours. You need to factor 2 top end jobs into the purchase price and do it as soon as you buy it. My guess is the current owner is afraid to even take you on a test drive knowing full well his motors are on borrowed time. That being said you have to respect the fact that these motors are still so strong after 17 years of use! Make him an offer but you need to discount for headers and a top end job minimum. That's what i learned anyway. Good luck

450 hrs---they are due for complete top end refresh's. Spend 6k to have them done soon or risk having to spend 15k if something lets go.

Ok, these are iron GM heads with .060 bigger valves. .600 lift and 150-430 spring pressures. For 500 approx hp. The ZZ502 has 527-544 lift. 120-300 springs. Couple degrees less duration and 110 lobe sep. Rated 502 hp at crank. They use the Eddy alum head which I have heard flows little better than an iron 990. Is there a cam halfway in between? Something around 230 duration 550 to 575 lift 112 to 114 lsa that wont require that much spring pressure? It seems like that is an unnecessarily sensitive valve train for 500 hp. And why spend 6k to refurbish stock GM iron heads when a new set of aftermarket iron heads are in that price range? And alum not much more?

Freshen up the heads and good gaskets and you're set for another 1500 hours, right? Sounds like a good idea to keep that cost in mind with the purchase price. Almost any boat you buy will need engine work, and I'd rather buy one that has been untouched.

When i was shopping for boats i found a local 342 baja in mint condition, had 500 efis w 650 hours, told owner they were PAST due for top ends and tried to negotiate it into a deal, he wouldnt budge, he thought they were rock solid to 2000 hours, i bought something else. He swore they had "good" maintenance, told him its a far cry from changing oil and minor service compared to doing top ends BEFORE they self destruct. Lmao, he told me to go on OSO , there was a guy who had 1000+ hrs on his near st lawrence seaway.

Sorry for that!!!! :)

Tough being famous huh ? LOL.