Piston rings- file fit or no for a stock 440?
- Thread starter Sonny
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Go with the stock cast iron rings. They will seat better, and you wont have to worry about filing them all the right size. Trust what all those engineers at Chrysler decided when they designed the motor, for dependability. After all we aren't on the Nascar circuit, trying to get every last horsepower out of these old cars, just trying to enjoy them.
Too much work for a stocker. Only for strict racers who are **** about 0.001 or 0.002!
Don't waist your time!
Don't waist your time!
mgoblue9798
Well-Known Member
Just my two cents, but I would get a moly ring pack they seat almost instantly. Regardless of what type I would at least need to put them in the bore and measure the ring gap.
FYI ... if you are getting KB hypereutectic pistons you will need file to fit rings or bad things will happen.
Just make sure the gap is big enough. A little to big is no concern. I'd use a set of Moly faced pre-gap myself.
Doug
Doug
What will happen? Does KB tell you what rings and gaps that it recommends?
MIKESPOLARA
Well-Known Member
I've never built a Mopar engine but have done plenty of engines. For my valuable money spent I would never assemble an engine, regardless of use without moly file to fit. I don't want problems/mistakes after the fact. Plus I always buy forged pistons
rip the top ring lands off.
Yes they do.
Sonny
It’s all fun til the rabbit gets the gun.
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GOOD ADVICE.....molybdenum faced rings will seat very quickly. Yes...install in the bore they will live in, MEASURE AND RECORD all the ring gaps (also both main and rod bearing clearances).....for posterity and future references. Just my opinion of course...
BOB RENTON
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Yes but people ignore the recommendations. Not enough gap, rings butt, piston breaks. KB's usually need .010 MORE gap than other pistons.
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Hyperutechtic is an cast aluminum alloy. An aluminum alloy that is satured with silicon is know as "eutectic." When the alloy contains silicon at a percentage that is less than saturated, it's called "hypoeutectic." When the alloy contains more silicon that then saturation limit, it's called "hypereutectic."
Compared to both 4032 and 2618 alloy forged pistons, hypereutectic pistons have less strength. Therefore, for performance applications using boost, nitrous oxide, and/or high RPMs, forged pistons (made from either alloy) are preferred. Hypereutectic pistons maintain their strength under high-heat conditions better than standard cast pistons. Although not as strong as forged pistons, hypereutectic pistons offer increased strength that raises piston reliability at a lower cost. All you wanted to know about hyperutechtic pistons (or not).....
BOB RENTON
Geoff 2
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Use Moly rings [ Moly top ring ]. Has faster break in than cast iron or chrome, plus unique lubricating quality, used for these reasons. No need for file fit in this application; there would be no noticeable difference that you could feel.
O.K., so humor me. The ring is installed in the cylinder and the ring gap is determined by
the diameter of the bore. In this case it would be around 0.016 gap with the temperature
at 72 degrees. As everything heats up, the bore expands, and so does the ring. The compression
ring gets the hottest because it's closest to combustion, but what does the material of the piston
have on the ring gap? The ring does not fit tightly on the piston, it has radial clearance. The
only way a ring can sieze up and rip the top land off is if the ring gap is too small. So, 'Splain
it to me Ricky!
the diameter of the bore. In this case it would be around 0.016 gap with the temperature
at 72 degrees. As everything heats up, the bore expands, and so does the ring. The compression
ring gets the hottest because it's closest to combustion, but what does the material of the piston
have on the ring gap? The ring does not fit tightly on the piston, it has radial clearance. The
only way a ring can sieze up and rip the top land off is if the ring gap is too small. So, 'Splain
it to me Ricky!
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It has to do with the accumulator groove between the top two rings on some KB hyper pistons. For some reason, (I don't know the reason) it results in a hotter top ring, requiring more gap. Without the extra gap (on THOSE pistons) the top ring butts, and oil cans the top of the piston off (or at least parts of the piston top....)
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IMO.....the material diffrrences allow for differential expansion. It's called the coefficient of linear expansion. The expansion is in all plane's.....diametral, thickness and radial. The Molly faced rings are treated or made from MOLYBDENUM DISULFIDE alloy which has excellent nonscuff, nonstick properties which allow higher operating temps without gauling. Ring gaps are extremely important to maintain and allow for the thermal growth required. Ring thickness and clearance in the ring land is also important. I believe that, due to the bore's cross hatching grooves, obtained thru honeing, beside providing an oil resivoire for ring lubrication, allows the rings to rotate as the piston travels up/down, unless the ring is pinned. There is a ring design, similar to a spirolox retaining ring, with overlapping ends, that, supposedly seals better than the traditional designs, but I have no personal experience with that ring. Just talking out loud.....
BOB RENTON
Geoff 2
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My understanding is that the alloying elements in the hypereutectic piston cause the piston head to run hotter; this heats up the rings, which in turn require larger end gaps.
The hotter piston head is supposedly what allows the HE piston to make more HP because the combustion gas loses less heat & maintains more force on the piston.
The hotter piston head is supposedly what allows the HE piston to make more HP because the combustion gas loses less heat & maintains more force on the piston.
I seeeee! Well, too much hocus pokus with Hypereutectic pistons! I'm old school
and will stick with the forged units. Thanks for "Splainin!
and will stick with the forged units. Thanks for "Splainin!
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