Piston ring gap HP500
02-05-2019, 02:28 PM
#1
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Piston ring gap HP500
anyone know were I can find mercruiser standard specs for piston ring end gap for merc HP500 carb?
I’m using JE pro seal sportsman series ring set and have flat top forged SRP pistons, bore 4,5”, closed cooling.
I’m using JE pro seal sportsman series ring set and have flat top forged SRP pistons, bore 4,5”, closed cooling.
02-05-2019, 05:08 PM
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Dis merc use je's in those engines it seems. This will be an interesting topic as to what is actual and what is recommended. Seems all over the board. I just read a thread that showed merc specs and then lost it however if I'm not mistaking it was like .011-.021 top ring and like .016-.024 second ring. This was off from an old thread that I was on and lost. Interesting.
Many like to use the .0045 per inch of bore for both and some .0055 x bore on the second. Your closed cooling will acct for a little difference also. Now what's strange I've also recall .0045 x bore then add an additional .002 for the top due to the heat.
Sorry I don't know the exact specs but just thought I'd throw some info out there. Seems like the wider gap on second ring can play a part in HP. Personally I'd call JE techline with piston part number and rings using and ask them. That way it's in there hands.
I leave it up to my machine shop who does many marine builds.
Many like to use the .0045 per inch of bore for both and some .0055 x bore on the second. Your closed cooling will acct for a little difference also. Now what's strange I've also recall .0045 x bore then add an additional .002 for the top due to the heat.
Sorry I don't know the exact specs but just thought I'd throw some info out there. Seems like the wider gap on second ring can play a part in HP. Personally I'd call JE techline with piston part number and rings using and ask them. That way it's in there hands.
I leave it up to my machine shop who does many marine builds.
02-06-2019, 06:01 PM
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If you are not using the factory pistons and rings then the factory specs mean absolutely nothing. Use the gaps that JE recommends in the paperwork that came with the rings. If you have any questions call JE and ask them. Simple as that.
02-07-2019, 11:28 PM
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OEM Merc Racing Hp 500 used JE Forged Alum pistons
ring gap per Merc was a production and service specs
top ring was .022 - .024 and the second ring was .020 - .022. Service was .010 over high production limit.
Oil ring was .015 -.055
ring gap per Merc was a production and service specs
top ring was .022 - .024 and the second ring was .020 - .022. Service was .010 over high production limit.
Oil ring was .015 -.055
Last edited by BUP; 02-07-2019 at 11:34 PM.
