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

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....!

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.

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

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"
jt

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

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