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502 MPI Gen V freshen w/ possible cam upgrade questions for the pros

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Old 11-26-2015, 07:16 PM
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The 4.466 je 700s had low tension oil rings, the replacement options allow you to get std tension as far as i understand, they are still metric however so last i seen they were double the price of normal rings.
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Old 11-26-2015, 09:37 PM
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I recently built a bone stock 502 MPI except for a custom hydraulic roller cam and associated valve train. This engine was built for a small m1 procharger (5 psi). I dyno'd it without the procharger and it made slightly over 500 HP, 730 with the procharger. That was in complete marine trim and wet lightning headers.

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Old 11-27-2015, 06:31 PM
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The 4.466 je 700s had low tension oil rings, the replacement options allow you to get std tension as far as i understand, they are still metric however so last i seen they were double the price of normal rings.
Ok I see! Is the reason to replace them the blow-by I have heard you mention in other threads?
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Old 11-27-2015, 06:35 PM
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I recently built a bone stock 502 MPI except for a custom hydraulic roller cam and associated valve train. This engine was built for a small m1 procharger (5 psi). I dyno'd it without the procharger and it made slightly over 500 HP, 730 with the procharger. That was in complete marine trim and wet lightning headers.

Bob
That would be great If I could do the same with the cam and get that power. What cam did you use for this?
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Old 11-27-2015, 09:43 PM
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My 502 had blowby since the day i picked boat up from Baja dealer brand new , took it back several times to dealer who tore motor halfway apart in boat (boat was less than 3 months old from new than), they let it freeze in parking lot and i took it out of there. I went thru motor myself back then, the rings were hard to find and expensive plus didnt like the glazed cylinders so I bought the je srp pistons that are a few thou over, tq plate honed the block and re-assembled it with std tension, american rings. have used those pistons in several builds since then with good results, I did see recently there was more 502 metric rings avail now than there was back in 1999/2000 so if your pistons are perfect and cylinders wont end up too loose I wouldnt say to NOT use them, fwiw, Smitty
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Old 11-28-2015, 12:29 AM
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The cam is one I spec'd from Cam Motion similar to a 500 efi grind. Don't remember exact specs but it was around 236/244 duration, .620ish lift, on 114 LSA with 2/3 4/7 firing order swap. I do have good headers that don't revert water easily. I would be a little more conservative on the cam otherwise.
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Old 11-28-2015, 01:07 PM
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My 502 had blowby since the day i picked boat up from Baja dealer brand new , took it back several times to dealer who tore motor halfway apart in boat (boat was less than 3 months old from new than), they let it freeze in parking lot and i took it out of there. I went thru motor myself back then, the rings were hard to find and expensive plus didnt like the glazed cylinders so I bought the je srp pistons that are a few thou over, tq plate honed the block and re-assembled it with std tension, american rings. have used those pistons in several builds since then with good results, I did see recently there was more 502 metric rings avail now than there was back in 1999/2000 so if your pistons are perfect and cylinders wont end up too loose I wouldnt say to NOT use them, fwiw, Smitty
So standard tension rings I will be sure and ask the machine shop about. The marina that tore my engine down subsequently sent out all the parts out to their machine shop who said I needed two new pistons. Not sure why they look ok to me but I'm no machinist. If I can reuse them I will but if I do in fact need two It may be more cost effective to replace them all with ones like you used.
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Old 11-28-2015, 01:11 PM
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The cam is one I spec'd from Cam Motion similar to a 500 efi grind. Don't remember exact specs but it was around 236/244 duration, .620ish lift, on 114 LSA with 2/3 4/7 firing order swap. I do have good headers that don't revert water easily. I would be a little more conservative on the cam otherwise.
I am getting the impression that the cam I called and spoke with Mark Boos about 230/230 and 578/578 @ 144 is about all I can use with my Stainless Marine exhaust.... but no proof one way or the other lol
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Old 11-28-2015, 02:43 PM
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So standard tension rings I will be sure and ask the machine shop about. The marina that tore my engine down subsequently sent out all the parts out to their machine shop who said I needed two new pistons. Not sure why they look ok to me but I'm no machinist. If I can reuse them I will but if I do in fact need two It may be more cost effective to replace them all with ones like you used.
Just DONT let them get merc replacement oem rings!
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Old 11-28-2015, 02:51 PM
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Just DONT let them get merc replacement oem rings!
Got it! If I have to buy the two pistons are the OE ones ok though?
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