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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" :mad:. 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?
 

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It's what we do
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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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Discussion Starter #3
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
 

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It's what we do
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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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AKA Blownjet 468
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couldn't have gotten a better explaination anywhere!:iagree:

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

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couldn't have gotten a better explaination anywhere!:iagree:

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

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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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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.:)sphss
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.:)sphss Even if the cylinder were bigger and walls were thinner.



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Discussion Starter #9
Yeah, about as round as you can get them with a ball hone.:)sphss
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.:)sphss 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 :badidea:
 

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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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AKA Blownjet 468
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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":p 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:D and explain it a little better;)
 

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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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Discussion Starter #14
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
 

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Discussion Starter #15
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":p 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:D and explain it a little better;)
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".

Now you guy's got me all "gun shy"... Good advice and I appreciate the concern regarding the SS Radius. I'm no "pro" by any means, but I did make some pretty decent side money in the mid 80's through the early 90's building cylinder heads. Still have all my die grinders, files and bits and seat grinding stuff somewhere.. Used to have a really cool home made head stand... Now granted I haven't touched a head in at least 15 years, Hoping I still remember which part of the motor that is :D

Is there really much HP to be gained in SS Rad? If I recall we only used to be concerned with the exhaust side anyways, as the SS rad was much tighter due to the shorter runner. There wasn't much to be gained with the intake. Comments?
 

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500 HP freshen

I do a considerable amount of work on the flow bench with #088 heads. The best things you can do without spending a lot of money is to blend the bowls, take the ridge out of the radius where it meets the bowl and reduce the casting around the guide area. Laying back the ss radius will lower and broaden the torque curve a bit.
A new cam and a pair of Dart Pro-1 ver. 2 heads with stock compression will yield you an easy 100+ hp as a bolt on. You can recon the stock "dimple rods", Polish the crank, line hone the mains. 500 hours, you are probably due for a new set of pistons, JE has them as does SRP
 

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Discussion Starter #17
I do a considerable amount of work on the flow bench with #088 heads. The best things you can do without spending a lot of money is to blend the bowls, take the ridge out of the radius where it meets the bowl and reduce the casting around the guide area. Laying back the ss radius will lower and broaden the torque curve a bit.
A new cam and a pair of Dart Pro-1 ver. 2 heads with stock compression will yield you an easy 100+ hp as a bolt on. You can recon the stock "dimple rods", Polish the crank, line hone the mains. 500 hours, you are probably due for a new set of pistons, JE has them as does SRP
Great info, and just what I was looking for.

Thank you.
 
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