I plan to do a budget rebuild (this winter project) on
my existing engine. I plan to reuse stock crank and rods,
maybe get crank polished, and I'll put in new bearings.

I'm courious about what pistons to get. I'm thinking about this:
Speed Pro hypereutectic H631CP30
Bore : 4.030"
Stroke : 3.48"
Dome Shape : Flat, 2 VR
Dome Volume :-5cc
Comp. Distance : 1.560"
Pin Type : Press or Float
Ring Size : 5/64, 5/64, 3/16
Piston Weight : 567 g. (approx)
Compression (@ .025 deck clearance)
58cc 64cc 68cc 72cc 76cc
10.41 9.73 9.33 8.97 8.63

And for rings:
Sealed Power moly rings
Bore size: 4.030" Top ring: 5/64" moly Second ring: 5/64" cast Oil ring: 3/16" stainless

What I have so far is stock shortblock with LPE 219 cam,
complete superram, 1.6 RR's, LT headers and ported #113's.

Also, while I'm in this rebuild, I plan to go with a little more cam.
here are specs:
Comp Cams XR288HR-10
Hydraulic roller
288 294 advertised duration
236 242 @0.050
520 540 lift
110* lobe separation

What do you think? Are those pistons any good?
I plan to keep revs up to 6500 max.

Thanks

 

Yep, nothing wrong with speed pro hypers. Pistons don't make HP, they just keep the engine running.
Keep in mind the compression height. 1.56" is an outright lie. It's a mistake from an old catalog, that they keep leaving in there! It's actually 1.54", and that affects your compression ratio. Deck the block to make it a zero deck height, and you're golden.
I'd invest in entry level rods, or ARP bolts for your rods. ARP bolts and resizing factory rods usually costs about the same as buying entry level aftermarket ones so.... (ohio crankshaft, $160 I think...)

 

I would probably go with just a regular set of cast rings, they tend to be a little easier to get seated in, since just your just going with pretty much a stock overhaul they would would probably work out a little better for you!
hope this helps!

 

It depends on the preparation of the cylinder walls. Cast and moly rings need different surface finishes.

 

It depends on the machine shop most shops will finish hone cylinders with a 200grit stone unless utherwise discused beforhand, witch is ideal for cast rings.

 

That should be +5cc dome volume. Negative indicates pop-top pistons.
http://store.summitracing.com/partde...0&autoview=sku A positive number indicates the pistons add to the chamber volume, a negative means they subtract from it.

I'm using Speed Pro hyper's in the Camaro, except they're +12cc and the skirts weren't coated (2005, about the time they quit offering uncoated).

 

I think that's just summits poor terminology. It's a flat top with 2 valve reliefs, they didn't classify it as a 'dome' piston. And speed pro H631's (if memory serves), is just another plain jane flat piston, so i'd guess it's 5cc of *dish*.

I thought machine shops finish hone based on moly rings being the standard. Cast rings I think are good for a backyard shade-tree hand-hone, but for any machine shop work, i'd use moly.
Just for clarification to the original poster, they're ALWAYS cast iron rings, but "moly" just means there's a hint of moly coating on the top face of the top ring. Also the outer diameter is coated.
*That's* the norm. You can also get rings made of different material altogether (rather than just coated), but that's kinda rare I believe.

 

Right. Dish adds volume to the chamber, pop-tops subtract volume from the chamber.

So a "positive" dome is a dish, and a "negative" dome is a pop-top.

(Now, is a one piece rear main seal flexplate external or internal balance??? )

 

A good shop will always discuss it beforehand.