Mercury HP-500
 

How well do these engines hold up? Maintinance, number of hours on engines ect. I'm possibly looking to re-power and trying to deside between HP-500's or a custon builder in the 500 HP range. Any insight or advise would be great.

Thanks Kirk

Kirk,

I have a 2001 500efi, 178 hours on it. Only thing I have had to replace is thermastat. Is very reliable, has always started right up even after sitting for winter, fires on about the 3 revolution.

Will:cool:

My friends cousin has twin Hp500's with prochargers in a 36 Cobalt cruiser. He's got 1100 hours on them in 2 years with no problems, and nothing but tune ups done. They are being worked on now only because he twisted a drive up. I'm guessing this is not the norm for these motors, but it speaks a hell of a lot about their durability....!:p

He now has a 42' Formula express cruiser with twin 575's that he's planning on putting around a thousand hours on it THIS YEAR in salt water. We are all curious how they hold up compared to the 500's with prochargers.:confused:

Friend has a 1995 42' Formula with triple HP500s (carb) over 600 trouble free hours and still going.

Anyone had any problems with valve spring breakage. I've heard that you should upgrade the carb. engines with EFI engine valve springs.
If so, does anyone know the part numbers for the upgrade springs??

43 Thunder,
one spring # that will work
is a comp cam 929-16,
retainer that will work,
crane 99961-16
valve locks: crane # 99098-1
hope this helps.
jt

you want go wrong
 

Get the Mercury hp 500's or even better find a pair of 540 Bulldogs - If it ain't Black - Send it Back - BH

BH,
Don' you mean"blue":confused: ;) :D
jt

ok-----YOUR RIGHT
 

If it ain't blue, it want do - haha - BH

I think somebody swapped the "O" for the "A" on BH's keyboard...:p

500 hp
 

i think the 500hp is over rated. i have 2 in my 34 magic, all they are is 502's that mercury changes the rings and bearings. if i had 15k laying around, i think i would have a good engine builder go though a set of 502's with 420 mega blower or whipple's that 700+ at the props. (just my 15,000.00 rebuild @ 200 hours opinion). hope this helps.

Re: 500 hp
 

I don't think so..................

Different cams, intakes, carbs, exhaust, + of course blue paint & some chrome stuff. They are also balanced.

500 hp
 

the motors are not balanced we have just rebuilt 2 of them. the intakes yes, cams maybe the rods are standard chevy. you would think they would at least have a h-beam style rod. the valve springs suck!!!!! i had 5 broken. and for the paint, the block heads and manifolds are black. i think, for the price of the motors
you should get more bang for your buck.

tom

tom

when you break a GM 7/16 dimple rod, THEN you can gripe. They are tuff rods. Merc is only using the H-beams in the 525 cause they can charge more. They don't need em.

It's a good strong package but
valvesprings are definitely the weak link.

If you're a motor head, you are far better off financially to "make" your own HP500 from a stock 502 core.

I will put two good HP500s on the classifieds next week. They are still in my boat and run awesome. One was just rebuilt and CRE sealed. I just put on polished pulleys, bypasses and new valve springs.

Thanks Andy
 

I just bought an HP 500, pick it up today & I had it shipped from Riverside CA. I looked around locally for weeks, could't find anything that I really liked, I knew as soon as I bought one, there would be somebody within a half hour of me with one.
I guess it always works like that. Then I go to the boat show & wanna upgrade, now I have a HP500 sitting around. Good luck on selling.
John:)

I actually have two for sale. They are still in my Outerlimits so that anyone can see run. One has ten hours since rebuild the other around 60. Both have new valve springs, clean Mobil 1, stainless crossovers and polished pulleys. What did you pay? Is $9000 a piece the right price?

Re: 500 hp
 

WOW, you must feel like a total AH having all this engine knowledge then paying Mercury all that money for nothing more than a good marketing effort:D