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-   -   Ring gap for hypereutectic pistons. (http://www.hotrodders.com/forum/ring-gap-hypereutectic-pistons-187748.html)

DT1 11-16-2010 12:41 PM

Ring gap for hypereutectic pistons.
 
Hi, everyone. This is my first post but I've been lurking for sometime and have found some very knowledgeable and interesting information here. I have many years of experience rebuilding Ford/Chevy small blocks and I usually shoot for stock. I also know that this is a hot rodders forum but I can't think of a better place to have my question answered.

I would like some advice from anyone that has experiance fitting rings for hypereutectic pistons.

I am rebuilding the engine for my 71 Chevy C-10, 350 SB, Bore .020 over, Mild RV cam, 8.5:1. Other than that, stock street and I'm installing Silv-o-lite hypereutectic pistons with a coated skirt. At first I was supplied with Hastings Moly rings but the gaps are close to .030 and I can clearly see, with my necked eye, that some of them are clearly not parallel. I returned them and ordered a set of Sealed Power .025 file fit, Plasma Moly rings.
After doing some research I'm getting conflicting information on the proper gap for top and second rings and was hoping that someone here can help me.
First off; Are "Silv-o-lite" pistons made by KB or do other manufacturers make them as well? The box that mine came in states Silv-o-lite but doesn't state the name of the manufacturer.
What is the proper formula for setting the top and second ring? I have always gone with .004 X 1.00 bore for top and .005 X 1.00 second for standard rings.
I'm reading things like "Top ring wider" "Second ring wider" and it's a bit confusing.
Also do the oil rings need any kind of special consideration?
Any input from some of you that have experience with this
combination would be greatly appreciated.

miller_time 11-16-2010 01:40 PM

i used to work in a performance engine shop. we set up all n/a engine ring gaps the same as you stated .004x1.00 top and .005x1.00 middle. cast,hyper or forged we ran the same gaps.

bprumos 11-16-2010 02:49 PM

apparently the oil rings dont need anything special, but ive heard the ring gap is supposed to be tighter on hyper pistons cause they dont expand as much and are a tighter fit in the bore when thier cold. i dont know if thats true as ive never personally delt with them first hand. from what i remember it was something like .010 smaller than cast pistons. so maybe more like .003x1.00in bore. i would call the piston manufacturer though and see what they recommend since they know all the details on the expansion rate of their pistons and what tolerances they feel is necessary for proper life and operation of their pistons. id listen to their recommendation unless i had hard evidence to say that their numbers were too loose or too tight. thats my .02 hopefully im of some help

ericnova72 11-16-2010 04:59 PM

Silv-o-Lite is just Silv-o-Lite, they are the makers(United Engine and Machine Co.) of these pistons, nobody but them uses that name. They are however, the same company that makes the Keith Black Hyperuetectic pistons, but the Silv-o-Lite hyperuetectic pistons are the budget standard rebuilder and claimer racing line, different then the KB's performance line.

The Silv-o-Lites use a standard ring gap, it is only the KB hypers with their higher ring position on the piston that have a special larger gap requirement due to being closer to the top gets them more heat, thus more heat expansion room is needed.

Use the formula you have always used.

F-BIRD'88 11-17-2010 07:01 PM

Ring end gap is relevant to the heat load the rings will see.
If you are going to tow or supercharge or otherwise run it hard you can open up the ring end gap.

KB/UEM has specific ring end gap guidelines. If you follow them you won't go wrong.


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