Double Rings! More Compression?

Took the rings out of my 2hp Upright IHC Aircooled and found two 1/8" rings in each grove instead of one 1/4" ring. I`ve seen this many times before but was wondering if this increases the compression if your cylinder is a little under par ?? Thanks - Shane

Shane, two rings will work in one groove, if they are sized correct. The groove to ring gap is most critical. Ring grooves should have no more than 2to5 thousand side clearance. The rings also will rotate in the cylinder if they are loose in the grooves. Then all your gaps will line up resulting in blowby and overheating the cylinder, thanks Doug

I'm restoring an 8-cycle air cooled Aermotor and it has two rings in each groove.

I ass-u-me that this was the way the Aermotors were shipped so I'm going to put them right back in.

Take care - Elden

Elden- Aermotor 8 cycles came from the factory with three 3" x 1/4" wide rings. Someone has made do with 1/8" rings rather than using the proper rings in your engine. As to using two rings per groove my experience is that there is little difference overall to the single rings. Some of the positive reasons for double rings are: 1)They will seat faster to an irregular bore since a narrower face is presented to the bore. 2) Availability of an oversize bore size or groove width can sometimes be solved by doubling up. Drawbacks are seen as 1) Cost. Double rings cost twice as much as singles in most cases since twice as many rings are being bought. The exception is where you need a custom made wide ring that is not currently available. Double rings most times are cheaper and are available immediately without a wait. 2) Double rings cannot be used in ported cylinders unless they are pinned to stop rotation. The ends of the rings can get caught in the ports and break. 3) This should not even be considered a drawback but there is often a distinct whine heard ofer the phone from some customers when suggesting double rings since they were not original equipment on the engine. This is about as lame as not using the correct Maytag script spark plug because they are no longer available. Nobody is going to see the rings at a show so who really cares? My recommendation is to use single rings if available. If not then double them up. If you still can't find the right sizes then go custom made. There is little difference between all of these except price. If your bore is worn and you think you want an oversize then you should be looking hard at the groove side clearances instead as mentioned here before. Thank you, Dave Reed Otto Gas Engine Works 2167 Blue Ball Road Elkton MD 21921-3330 phone 410-398-7340 http://www.pistonrings.net




click here to go to the piston ring web page

Reminds me of what my Dad did to a Waterloo Boy 3 hp about 50 years ago. He used 2 rings per groove simply because that was all he could get at the time. Worked fine for many years as I recall.

WELL SAID DAVE. YOU GOT TO PAY ATTENTION TO THE PISTON. ALL THE BORING, HONING AND WHAT EVER ELSE YOU CAN THINK OF WON'T BE WORTH A DIME IF YOU DON'T PAY ATTENTION TO THE RING GROOVES.

Dave:

Thanks for the information about piston rings for the Aermotor engine.

I don't have the piston here but, when I cleaned it up, the rings were a nice fit in the grooves so I ass-u-me that the grooves are in good shape.

I've saved the link to your page.

Take care - Elden

Someone before me doubled up the compression rings in my Stover due to a much oversize cylinder ( wear ) so they wouldn't have to replace piston I would guess and it runs very well with excellent compression. I don't see where any harm could come from it except as noted by pistonring in the case of a ported cylinder.