speed pro vs sealed power pistons

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swing69

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Whats the feelings on speed pro vs sealed power pistons for a stock build?

Same part numbers except "AP" vs. "NP" letters.

For example: 318 pistons with valve reliefs are 285AP ($13 each) or 285NP ($7 each).

SHOCK? how good can a $7 piston be?
 
swing69 said:
Whats the feelings on speed pro vs sealed power pistons for a stock build?

Same part numbers except "AP" vs. "NP" letters.

For example: 318 pistons with valve reliefs are 285AP ($13 each) or 285NP ($7 each).

SHOCK? how good can a $7 piston be?
Click to expand...

Where are you getting these pistons!!! I need 8 For a 273!!
 
From the specs - same parts. Those are stock type deals. They'll do fine for a stock build.
 
one of the other pistons listed had a .020 higher piston height the others you selected were .020 shorter might get a little more compression from them unless it was a misprint.
 
SEALED POWER 285AP {#285NP}
Cast; .9842" Pin Dia.; 2 Rings: 5/64 Groove; 1 Ring: 3/16 Groove; 1.720 CD; Flat Head w/ 4 valve reliefs; Designed for full-float or press-in-rod pin - 8.5:1 C.R.

From the rockauto site. should be the same. pricing diff: ~$7 vs. $24 std bore price.
 
Speed Pro and Sealed Power are BOTH made by Federal Mogul... Same company, similar/same pistons...
 
I do not know about those particular parts, but Speed Pro was forged and .020" taller, and sealed power was cast aluminum.
 
Marcohotrod said:
I do not know about those particular parts, but Speed Pro was forged and .020" taller, and sealed power was cast aluminum.
Click to expand...


NP = speed pro. from Rock Auto:

SEALED POWER 285NP Cast Piston
Fits Cast; 2 - 5/64 Groove, 1 - 3/16 Groove, 1.720 CD, Flat Head w/ 4 valve reliefs; Designed for full-float or press-in-rod pin - 8.5:1 C.R., 0.9842" Pin Dia.
Or 2-5/64, 1-3/16 Ring Grooves; 1.720 CD; 0.9842 Pin Dia. Flat Head w/ 4 valve reliefs. Designed for full-float or press-in-rod pin - 8.5:1 C.R.; 8 Req'd
Or Cast; 2 -5/64 Groove; 1 -3/16 Groove; 1.720 CD; Flat Head w/ 4 valve reliefs; Designed for full-float or press-in-rod pin - 8.5:1 C.R.; 0.9842" Pin Dia.
 
Just got the pistons. seems the top edge has a larger chamfer and its a flat top, no valve reliefs!

How critical are the 4 valve reliefs on the 68 318 stock build? later 318s have the std. flat top.

Anyone know???????
 
Someone feel free to correct me if I'm wrong, but..... OP if your asking about four valve relief pistons for a two valve engine, and don't take this the wrong way, it's honest advice, you may want to have someone else picking parts and building your engine.
 
valve reliefs are for piston to valve clearance, reliefs are very needed with large cams, probably not needed in your engine with a mild cam, but clearance should be checked to be safe
 
I just checked through the SilvoLite catalog for comparison and the pistons that you received might possibly the even lower compression truck pistons; they will be god-awfully low compression and I don't think any stock cam could ever hit them with a valve! FM part number for those is LC371P.

www.uempistons.com/catalogs/silvolite_catalog.pdf

Do you have any way to accurately measure the distance from the top of the piston to the top edge of the piston pin bore? (Use a fine metal scale if you do not have a caliper.) If so, add that number to .492" to get the compression height. For the FM285NP, the CH should be around 1.740". For the lower compression truck pistons, CH will be around 1.660". If you need help with the math, post here or PM me.
 
PhilH: no offense taken...... :) The stock cast piston design has 4 valve reliefs. I need to replace 1 due to damage from mishandling once removed. Here is a 273, but the 318 has the same 4 reliefs. the same piston is used on both banks, so 4 would be needed, rather than 2 reliefs, even though a 2 valve head.

Marco and nm9: from the Rockauto description: SEALED POWER 285NP Cast Piston
Fits Cast; 2 - 5/64 Groove, 1 - 3/16 Groove, 1.720 CD, Flat Head w/ 4 valve reliefs; Designed for full-float or press-in-rod pin - 8.5:1 C.R., 0.9842" Pin Dia.

I will measure the "no relief" pistons to see if the CD is the same as spec'd.
 

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swing69 said:
PhilH: The stock cast piston design has 4 valve reliefs. I need to replace 1 due to damage from mishandling once removed.

Marco and nm9: from the Rockauto description: SEALED POWER 285NP Cast Piston
Fits Cast; 2 - 5/64 Groove, 1 - 3/16 Groove, 1.720 CD, Flat Head w/ 4 valve reliefs; Designed for full-float or press-in-rod pin - 8.5:1 C.R., 0.9842" Pin Dia.

I will measure the "no relief" pistons to see if the CD is the same as spec'd.
Click to expand...

No, the stock pistons aren't made for four valves, they just have a relief to lower the compression, flat top pistons that raise the compression depending on the cam might need a relief cut into it to clear the valves depending on the cam being used. You like ME are learning this as we go, do ALOT of reading to get an understanding of how a rebuild goes. I was very worried about spending thousands and have it go bad ( which is still to early to know for sure ), and just trying to keep you from making an expensive mistake. Read read read, buy the books follow to a T, I'm real happy I did it and not had someone build it for me.
 
That pic did not come up when I saw the last post. Now that I see it, that is not a stock piston, that is a stock replacement, lil different.
 
the piston must be installed with notch forward, thus 4 reliefs to switch banks.
 
fishmens67 said:
the piston must be installed with notch forward, thus 4 reliefs to switch banks.
Click to expand...

x2.

On the choice - if this is to replace one, you should verify it is exactly like the others at least in terms of weight. Aside from that, given it's a mild 318 build, it should work fine for you. If you were replacing a set I would have suggested something more performance oriented - but this is a fix. Assuming what you have are the same basic weight (within 20-40 grams) it will be fine.
 
swing69 said:
Marco and nm9: from the Rockauto description: SEALED POWER 285NP Cast Piston
Fits Cast; 2 - 5/64 Groove, 1 - 3/16 Groove, 1.720 CD, Flat Head w/ 4 valve reliefs; Designed for full-float or press-in-rod pin - 8.5:1 C.R., 0.9842" Pin Dia.

I will measure the "no relief" pistons to see if the CD is the same as spec'd.
Click to expand...
Understood, just suggested a possibility since these are so different from the actual Sealed Power/FM description. It is coming from a parts warehousing company; they make mistakes and dumb substitutions at times. And x3 or x4 on the 4 valve reliefs.... it took while for that to get through my skull when I first ran across it.
 
Still not getting the four valve relief thing??? Yes the notch goes forward, but the piston doesn't care what side off the engine it's on, as long as one side goes the same way the others go the other way. My speedpros have 2 reliefs and one side notch goes back and other side goes forward, but all the reliefs end up on the top side of the piston. Now the cast originals had a HUGE dish, low compression and no relief. So did factory pistons come flat-top with reliefs?
 
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