I came across these Pistons but not sure I want to use them? They are press fit for starters, also they do not have wrist pin oiling holes, I also found very little info, but what I have heard is that they need to be fly cut or something? Can anyone chime in or have opinion on using these Pistons for my 454 build? Thanks


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There is a groove at approximately 2:30 in your picture showing the wrist pin bore, that is the pin oiling groove.  I wouldn't fly cut them, which is done to reduce compression.  Check your piston to valve clearance, especially on the intake, then only cut what is necessary to achieve .080 to .100.  The advertised compression ratio is always generous, you don't want to lose any more than is necessary.  You could help flame front propagation by gently hand sanding the sharp edges off of the dome and valve reliefs only.

Jeg's lists them as the following:

Sealed Power#844-L2465F

454ci Open Chamber Race Piston, .000'' OverborePiston Dia.: 4.251''Piston Top: 25.7cc DomePressed PinComp Ratio: 11.31:1 w/100.9cc Heads, 9.61:1 w/119cc HeadsSold as Each

$62.99

What heads do you intend to run?  What about your cam/rockers?

If you are already contemplating new pistons, you should match the compression ratio to your cam.

I also have no info about these Pistons? I don't know how much they expand when at operating temp? The piston to walk Clarence etc?


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781's you will be right on the brink of needing fancy gas. Be sure of the tune your putting in it.


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If we assume a typical 9.7cc gasket with a deck height of the piston down in the hole .025 at TDC and estimate the combustion chamber volume at 119.6cc (my heads as measured), the advertised compression ratio wasn't to far off at 9.612:1.

If you zero-deck the block, that will bump you up to a theoretical 10.103:1.  Zero-decking the block will reduce the quench height; therefore increasing the turbulence in the combustion chamber, increasing the efficiency of the burn, and most importantly increasing resistance to detonation.  If you can keep your quench height under .055, you can run more compression and be less octane limited at the same time.

Just be advised that any deviations from my numbers will result in different, and unique to your application, compression ratio numbers.  You might find that your heads actually measure out at 122-124cc which would put you in the 9.43-9.28:1 range with a deck height of .025 and 9.89-9.73:1 range with a zero-decked block.

I would bet that with .505/.515 lift, you will not have to machine the valve relief pockets.

...what I have heard is that they need to be fly cut or something? Can anyone chime in or have opinion on using these Pistons for my 454 build? Thanks

Getting back to your original question, after all that ciphering, it is possible that with your combination of parts, your compression might be a touch on the high side.

First thing I would do would be to cc your cylinder heads and calculate your real static compression ratio to see where you really are rather than guessing.

Next, I would mock up the cam and valve train to check the piston to valve clearance on every piston.  Sometimes the cam bearing bores and lifter bores are a little off, affecting cam timing.  One bank will be advanced and the other retarded.  This will help you later when you are degreeing your cam.  Cut the valve relief notches to the deepest required to achieve .080 clearance on the intake and .100 clearance on the exhaust on every piston.  Once the maximum cut depth is determined, make every cut the same in every piston.

Keep in mind that advancing the cam will decrease intake valve clearance and retarding the cam will decrease exhaust valve clearance.  On an OE Chevy head, the exhaust valve is deep in the combustion chamber and far away from the piston at TDC, but you will want to check it anyway.

Then, I would blend a radius into the valve relief where it breaks out into the outside diameter above the top ring.  Be sure NOT to grind any closer to the top ring.  This will substantially increase the strength in this area.  Take care to make each radius the same from piston to piston to avoid variations in piston mass (balance) and compression.

Lastly, I would hand sand a radius on the sharp edges of the dome followed by the sharp outer edges of the valve relief notches.  Again, be careful to make each piston exactly the same.  Pick one feature to modify and do every piston before moving to the next feature.  DO NOT go to town on one piston and then move to the next piston.

All of these modifications will lower compression.  I would then re-measure the cc's of the piston domes and calculate your New compression ratio.  This will probably get you to where you need to be without fly cutting the domes.

If your compression is still too high at this point, I would angle cut the dome (your machinist will hate you) biased towards the exhaust valves, leaving the dome under the intake valve uncut.  This will bias the squish and force the air/fuel charge towards the hot side of the cylinder when the piston approaches TDC on the compression stroke.  This will help cool the exhaust valve, will pack the air/fuel around the spark plug, and increase turbulence in the cylinder.  Ultimately this will promote a more efficient burn while reducing octane limitations compared to just making a flat cut off of the dome, but requires more setup time and measuring.

Good luck,

Joe