Rebuilding 502 Gen VI
07-25-2002, 06:27 AM
#1
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Rebuilding 502 Gen VI
I have two motors set up exactly the same, Impco exhaust, holley 850 cfm marine carbs.
One motor started burning three to four quarts in a day.
All 502 motors burn some oil due to the low restriction design oil rings.
At the moment we feel that the failure was due to excessive fuel and cylinder wall wash down.
I have a brand new block, and here is where I need some advise.
Do I install my old pistons with the new low restriction oil rings or do I bite the bullett and acquire new pistons and go with the conventional rings?
Any suggestions would be appreciated.
Thanks
One motor started burning three to four quarts in a day.
All 502 motors burn some oil due to the low restriction design oil rings.
At the moment we feel that the failure was due to excessive fuel and cylinder wall wash down.
I have a brand new block, and here is where I need some advise.
Do I install my old pistons with the new low restriction oil rings or do I bite the bullett and acquire new pistons and go with the conventional rings?
Any suggestions would be appreciated.
Thanks
07-25-2002, 08:00 AM
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Been there, done that...
BBT,
I built my first high perf engine looking for every last HP. I installed low tension oil rings as well...big mistake. These rings should NOT be installed in a wet sump system; they cannot handle the amount of oil been splshed on them. They were designed for dry sump systems. By all means, if the pistons look fine, re-use them. Just make sure to put a new hone to the block and install a whole NEW set of rings with standard tension oil rings. If you use the old rings, you'll still have the problem of them not seating. The amount of HP you save from the low tension rings will never show up on a boat speedo - the drag strip, yes you'll see some difference.
I built my first high perf engine looking for every last HP. I installed low tension oil rings as well...big mistake. These rings should NOT be installed in a wet sump system; they cannot handle the amount of oil been splshed on them. They were designed for dry sump systems. By all means, if the pistons look fine, re-use them. Just make sure to put a new hone to the block and install a whole NEW set of rings with standard tension oil rings. If you use the old rings, you'll still have the problem of them not seating. The amount of HP you save from the low tension rings will never show up on a boat speedo - the drag strip, yes you'll see some difference.
07-25-2002, 07:35 PM
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Have a 502MPI mag did exactly the same you are talking about. Went from using a quart (depending on drive habits) every 10 to 20 hrs to using 3 + in less that 4 hours. Ran it pretty hard that day but it had NEVER used oil like that. Had black transom only it was now oily too. It did this real quickly not over time. One weekend it was fine and the next it was what happened to the oil? Found I had sucked an intake gasket between 6-8 cyl and also pulled gasket in from valley that was sucking in mucho oil. I ended up freshing the heads and lower end at the same time. Cylinder walls and lower end looked almost new. Pistons were not scuffed or too loose. Not new but still would run for a while in my opinion. I just installed new rings, bearings, headjob just a refresh and rock and rolled. But I was in a hurry and money was some what tight.
As for using old parts just depends on wear on parts number 1 and budget number 2. New is usually prefered. Low tension rings are another subject. I agree with razor.
As for using old parts just depends on wear on parts number 1 and budget number 2. New is usually prefered. Low tension rings are another subject. I agree with razor.
