Piston choice?
Thread Starter
Le Mans Master
Joined: Nov 2004
Posts: 6,128
Likes: 21
From: North Alabama
Piston choice?
Well, as most stated here, if you dig in a little, you'll end up going all the way. After finding an ear off one of the piston skirts, I decided to tear the engine completely down. The current pistons are 4 valve relief pistons. For replacements in the rebuild, should I stay with the 4 valve relief when buying the new pistons? Or go with a 2 valve relief or flat top as other choices? The block is standard bore but will probably be taking it to +.10 to +.20 over because of some minor cylinder wall scoring. Suggestions welcome and appreciated! 
Melting Slicks
Joined: Jan 2004
Posts: 2,672
Likes: 1
From: New Cumberland PA
Originally Posted by Schmucker
I don't think it matters very much. You want whatever pistons will give you the compression ratio you desire with your heads. I'd probably just put some flat tops in there.
There is not much of a difference, may only be a couple of .10's. However, this is one way of getting the CR fine tuned to what you think is best.
Melting Slicks
Joined: May 2001
Posts: 2,131
Likes: 4
From: May help you? You can sure as hell try!
Personally, I like Speed Pro's hypereutectic cast pistons. The castings are strong enough for moderate performance use and can be fitted tighter than forged pistons. That means less opportunity for piston slap noise and better oil control. They also have a low friction coating which should help reduce friction a bit and definitely reduce the chances for scuffing. Don't get hung up if the replacements don't have 4 valve reliefs. GM did that so they could use the same pistons in either left or right banks. Just make sure that you install the pistons in the right orientation if your replacements have only 2 reliefs.
The hypereutectic pistons are also considerably cheaper than forged.
Keith Black also has decent hypereutectic pistons but I don't think the skirts are coated and they recommend a slightly larger top ring gap.
Buy Sealed Power piston rings with a moly top ring. Anything else is overkill (and over priced). You should be able to get a SP ring set under $50.
You may also consider replacements with a slight pop-up to up the compression a bit for more performance. If you stay below 10:1, you should be able to run on pump gas and not get into spark knock.
The hypereutectic pistons are also considerably cheaper than forged.
Keith Black also has decent hypereutectic pistons but I don't think the skirts are coated and they recommend a slightly larger top ring gap.
Buy Sealed Power piston rings with a moly top ring. Anything else is overkill (and over priced). You should be able to get a SP ring set under $50.
You may also consider replacements with a slight pop-up to up the compression a bit for more performance. If you stay below 10:1, you should be able to run on pump gas and not get into spark knock.
