How finicky are the old carbed HP500's? Some tell me that they are alot of trouble. I'm looking at a couple of boats with these engines but I don't want to be fussing with the motors every (or every other) time out!

Do they run on 89 Octane? Is it true that you need to re-do the upper end every 200 hours? Are the regular 502/415's more reliable?

Thanks

I had a pair of 98's.

one broke a lifter around 190 hrs, due
to the valve spring issue they had with
that era of engines, after that, ran them
another 250 hrs without any issue.

They run on 87 octane

Some say do the springs/lifters around 200 hrs.

Reliable ?....I'd say there as reliable as reg 502/415

I would have no problem owning them again.

I had one of the latest carb versions of the HP500. It actually had the updated springs. Had 175Hours. No problems. Run em like you stole it. Built to last, perfect start everytime.

Oh yeah, since there are 400+ miles of canals here in Cape Coral, we end up doing alot of idling...Is that a problem with these engines, you know, for like carbon build up or something...?

no problem very idle friendly

hp500 carb is a 502cid. at 200 hours the valve springs should be replaced and you can hear it when they haven't been. get documentation if they have been changed out. it cost me less than $1200 to replace the springs (on 2 engines).
your going to hear different opinions what to do after that such as going thru the whole valve train (topend refresh or even more) at +/- 500 hours or so, i'll cross that bridge when i get to it.
right now mine are running very well at 245 hours and are 10 years old.
i'm not a WOT kinda of guy but you do have to run them to keep the carbs cleaned out and yes i run mine on 89. they have a tendency to soot at idle (rich) so try to get the idle/mixture dialed in as best you can.
they are a strong engine nothing wrong with older technology.
good luck
jim

It is an excellent engine and I would not hesitate to buy a boat with them. As with any purchase, have them inspected,compression test, leak down, etc. You definately need to change the springs. Other than that, run the snot out of them.
Eddie

Upgrade valve springs at 250 hours. I did mine again at 420 hours and recently rebuilt car to pan at 600 hours. No issues ever. Idle smooth and run sweet. 600 hours before rebuilds is about as reliable as you can get I think. I love mine.


RAF

Yeah,
i can't wait to install mine 98 HP500s take outs, (70 hours on them!) in the Nordic. Just got find the time!
I think it's one of the best "Blue" motors ever built. I had 98 HP500 in my Velocity , and that thing ran like a champ all the time!
Dean

I've heard the same and also applies to the 500EFI and any other engine with 500+ HP. New springs/lifters around 200hrs.