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How much to refresh pair of HP500's?

Old 02-21-2006, 09:28 PM
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Default How much to refresh pair of HP500's?

I'm looking at buying a boat with a pair of HP500's, I'm aware of the "broken valve spring" problem with these engines. They currently have a little over 200 hours on them. When should I look to refresh them? More importantly HOW MUCH per engine? I'm in Miami so I'd go with someone local, obviously have lots of options.

Thanks!
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Old 02-21-2006, 09:37 PM
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Default Re: How much to refresh pair of HP500's?

depends on hrs ect but you can figure on atleast 5-7k per if done right Id be closer to 7 or more but I use the best of everything (thats the only way I will build a mtr)
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Old 02-21-2006, 09:54 PM
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Default Re: How much to refresh pair of HP500's?

Is that for a full refresh or just the often referred to top end of the motor? I've heard the top end is all you need the first time if doing around 300 hours, then the second time is a full? Bit confused here?
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Old 02-21-2006, 10:01 PM
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Talking Re: How much to refresh pair of HP500's?

If you dont have any broken valve springs in the motor now all you should need are springs and lifters after you do a compression test and leakdown test. The biggest problem is water getting back in the engine and ruining valves and valve seats. Then if that happens you need to pull the intakes and heads and do a valve job. Of course more cost, head bolts, head gaskets, intake gaskets, oil, oil filter and sealer. If you do want the boat I would suggest an engine survey done by a compitant mechanic.

John S.
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Old 02-21-2006, 10:04 PM
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Default Re: How much to refresh pair of HP500's?

Miamioffshore,
Call Mindi Doller at Doller offshore-They are in Hollywood Fl.
She will give you straight answers. They rigged my boat for Sonic. Heres their number 954-237-0332. Tell Mindi, Tom will the Sonic 386 sent you.
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Old 02-21-2006, 10:13 PM
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Default Re: How much to refresh pair of HP500's?

IM figuring a full refresh.... brgs, rings heads ect... you didnt state the hours so have to figure the worst case......

but have to agree with john get a survey then decide how far you want or need to go
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Old 02-21-2006, 10:17 PM
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Default Re: How much to refresh pair of HP500's?

I just did mine this winter, saw some lifter wear in the motor that stayed together along with some lower bearing wear. Not enough to get excited about in the bottom end. Got my attention on the top side. Had around 325 hours on it. I had changed my springs at 280 or so and found 2 broken inners on 1 motor. I'd get into the whole motor, maybe a valve job and resurface on the heads, re-hone, re-ring and bearing it. Check the lifters and replace if needed. Depends on how much you want to spend now vs. later.

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Old 02-21-2006, 10:50 PM
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Default Re: How much to refresh pair of HP500's?

Originally Posted by Pwrbt33
If you dont have any broken valve springs in the motor now all you should need are springs and lifters after you do a compression test and leakdown test. The biggest problem is water getting back in the engine and ruining valves and valve seats. Then if that happens you need to pull the intakes and heads and do a valve job. Of course more cost, head bolts, head gaskets, intake gaskets, oil, oil filter and sealer. If you do want the boat I would suggest an engine survey done by a compitant mechanic.

John S.
And how does water get back in the engine ? Are we talking reversion here or is this something HP500's are prone to for some reason?
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Old 02-21-2006, 11:19 PM
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Talking Re: How much to refresh pair of HP500's?

You could call it reversion. What happens is when the spring or springs get weak and the piston moves down in the bore it can sometimes pull the valve open and cause a suction effect in the exhaust system. Which at times may pull water back in the tail pipe. Not saying that will happen to you. Most people like to say reversion is from camshft overlap or not enough idle rpm. Plus water in the tail pipes is common on boats with molded in swim platforms and short tailpipes. When you pull off the throttles and let the water rush the back of the boat it has no where to go. So it pressurizes under the platform and goes to the place of least resistance....the tailpipe. I have even seen some engines where they start to stahl out and idle funny because of the water getting in.

Again... just my .02.

John S.
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Old 02-22-2006, 06:37 AM
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Default Re: How much to refresh pair of HP500's?

On the early 500's with Gil exhuast alot of them would start to leak between riser and manifold and cause reversion problems. Alot depends on how the boat was run as to when it would need a rebuild. At 300 hrs without knowing how it was run I would do a full rebuild. Figure 8-9k per motor incl R&R from a good shop.
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