Freshening up my HP500
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Freshening up my HP500

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    Can't re-Member 28Eliminator's Avatar
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    Default Freshening up my HP500

    Need some advice and help from the pro's in here;

    My Boat has a 97 HP500 Merc in it with 520 ish hours on it. I noticed a couple blue "Puffs" out of the exhaust last year when I started it cold a couple times. Nothing major, and not every time, but enough that I'm concerned that it might be "time" . It also has developed a little valve train noise. I changed the valve springs last year, didn't find any broken ones, and it didn't cure the noise. Lifter maybe?

    Other than those issues, it still runs good.

    Any one care to take a shot at what it will cost to go through it? Machine work and parts?
    I'd agree with you, but then we would both be wrong

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    It's what we do BDMarine's Avatar
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    The blue puff is probably the valve seals and not a big deal. However, the HP500 does not have a round cylinder and the hone leaves a lot to be desired from the factory. Bore and torque plate hone the cylinders to 4.500 (approx. depending on piston diameters) JE makes a replacement "shelf stock" piston for that engine. Align hone, surface and square the block. Don't cut corners if you are going to rebuild it. Replace the lifters, push rods, rockers, rod bolts and nuts, oil pump and drive, distributor gear, timing chain and gears, etc. Remember, every part in that engine has 520 hours on them. Pay a little more now and get another 600 worry free hours out of it.
    I would surface the heads, check guide wear and replace the valves as well. You said the springs were just done so they should be fine.
    Feel free to call and I will give you some ideas on cost.
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    Quote Originally Posted by BDMarine View Post
    The blue puff is probably the valve seals and not a big deal. However, the HP500 does not have a round cylinder and the hone leaves a lot to be desired from the factory. Bore and torque plate hone the cylinders to 4.500 (approx. depending on piston diameters) JE makes a replacement "shelf stock" piston for that engine. Align hone, surface and square the block. Don't cut corners if you are going to rebuild it. Replace the lifters, push rods, rockers, rod bolts and nuts, oil pump and drive, distributor gear, timing chain and gears, etc. Remember, every part in that engine has 520 hours on them. Pay a little more now and get another 600 worry free hours out of it.
    I would surface the heads, check guide wear and replace the valves as well. You said the springs were just done so they should be fine.
    Feel free to call and I will give you some ideas on cost.
    Thanks for the reply. 2 questions, " does not have round cylinder"?? can you clarify on this one for me. The other, in regards to the valve seals, did these motors use the teflon type that are fixed to the top of the guide, or the old "Hat" style rubber ones?

    Also, What heads did these motors use, and are they any good?

    Thanks for the help
    I'd agree with you, but then we would both be wrong

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    It's what we do BDMarine's Avatar
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    The cylinders were not torque plate honed, so when the head is torqued it distorts the cylinders a little. They're round, just not the best.

    Trying to remember, but I think they used a "hat" type. We always install a good viton pc type.

    The heads are GM cast iron rectangle port. They are good heads and have more potential with a little port work.
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    couldn't have gotten a better explaination anywhere!

    p.s. , speaking of 088's, how'd that head work out for ya?


    Out With The Old, In With The New.......Goodbye Blinding Acceleration, Hello Sustained High Speed (in comfort)

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    Quote Originally Posted by Blowncat 509 View Post
    couldn't have gotten a better explaination anywhere!

    p.s. , speaking of 088's, how'd that head work out for ya?
    It worked out great. Thank you!!!
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    Default rockers

    If it has a good set of roller rockers on it check them out real good make sure the bearings are all good in them and use them i have seen roller rockers go alot more hours than that

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    gn7
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    Quote Originally Posted by BDMarine View Post
    The cylinders were not torque plate honed, so when the head is torqued it distorts the cylinders a little. They're round, just not the best.
    .
    Yeah, about as round as you can get them with a ball hone.
    Its funny, but Detroit learned a long long time ago that the bigger the bore gets, the more critical the bore becomes. Guess they forgot by the time they got to 4.470. So the same process that was used for the 427/454 was good enough. Even if the cylinder were bigger and walls were thinner.



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    Last edited by gn7; 12-22-2010 at 05:31 PM.

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    Quote Originally Posted by gn7 View Post
    Yeah, about as round as you can get them with a ball hone.
    Its funny, but Detroit learned a long long time ago that the bigger the bore gets, the more critical the bore becomes. Guess they forgot by the time they got to 4.470. So the same process that was used for the 427/454 was good enough. Even if the cylinder were bigger and walls were thinner.
    So it sounds like takin out the ridge, Honing and re-ringing it's out of the question
    I'd agree with you, but then we would both be wrong

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    Quote Originally Posted by BDMarine View Post
    The heads are GM cast iron rectangle port. They are good heads and have more potential with a little port work.
    Match port, Bowls, and short side radius?
    I'd agree with you, but then we would both be wrong

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    I have been following this thread as I also have an HP500EFI that just turned 400 hours, no issues, just planning ahead at this point and have a couple of questions, first for ELIM 28, is your a carb or EFI version? And second for the responders, anyone have a good cam rec that would be an upgrade for the stock cam? Thanks, and Happy Holidays All!
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    Quote Originally Posted by 28Eliminator View Post
    Match port, Bowls, and short side radius?
    If you don't know what you're doing as far as porting heads-I really wouldn't go anywhere
    near the shortside radius with a grinder! that is a tricky area, and best left to the pro's!
    seen alot of ruined heads because people got in over their "head" thinking they could
    do it themselves! not sayin' you don't know what you are doin' just sayin'......
    'bout time for steelcomp to chime in and explain it a little better


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    gn7
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    Short side has some pretty simple rules. Rule #1- once the gennie is out of the bottle, you can't get him back in. Translates to: once the metal is gone, its gone. These are iron heads. No filling it back in. Want to see a piss poor flowing head, look at one where the short side is jacked up. One of the easiest and best ways to get a better short side is to go to a larger valve, and let it set a little higher. Gives you a little more head to play with. But its still "pro territory".



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    Quote Originally Posted by Bubbletop409 View Post
    I have been following this thread as I also have an HP500EFI that just turned 400 hours, no issues, just planning ahead at this point and have a couple of questions, first for ELIM 28, is your a carb or EFI version? And second for the responders, anyone have a good cam rec that would be an upgrade for the stock cam? Thanks, and Happy Holidays All!
    Mine is Carbureted
    I'd agree with you, but then we would both be wrong

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