For most builds, I’ll use a moly top ring and a cast 2^nd ring.  Moly rings will stand up to higher temperatures without a loss of radial tension and the second ring in most cases is simply an oil control ring.  The moly itself does allow for some oil retention which in itself keeps the wear factor on both the rings and cylinder walls less than what you’ll find on a similar sized cast ring.  Radial tension is a key factor here also.  Once the ring size drops to 1.2mm or less, there is not enough surface area for a groove for the moly to be imbedded within it.  In these cases, I simply use a tool steel top ring.  While I personally don’t use rings any thinner than 1.0mm, I have seen rings with the widths as small at 0.027” which is just a tad thicker than a oil ring support rail.  While most modern rings prefer a cylinder wall finish or 400 or finer, I have experimented with 800-1000 rms cylinder wall finishes but these can be tricky to break in.  With the finer finishes, the initial oil application on the ring prior to installing within the cylinders is important as most ring break in occurs within the first five-ten minutes of engine run in.

Lorena, Texas (South of Waco)

Yes, I remember the cylinders looked like a mirror finish on the 302 I built using moly rings as opposed to the cross hatch finish for cast.

hastings made cast rings, chrome rings as well as molley,as you probley know the molley is sprayed on the top ring,and cylender finish should be finner than chrome and chrome finer finish than cast usualley the ring packs onley differ on the top ring. it apears2nd rings are  changed from 1 set to the next. would be interesting to go to a seminar hosted by ring co,s. does any 1 know what the ys at the engine comp used for rings,very impresive results frome the 2 ys in the competition. just read the recent hotrod storey on the Ys

I don't expect any issues, it already has 6000 miles on it and I've used cast rings on a lot of engines in the past. I've only used Moly rings once on my 302..

RANCHERO JIM ,I DOUGHT YOU HAVE ANEY ISUES. MOLLEY RING DECISIONS SHOULD BE MADE AT REBUILD POINT,AS CYLENDER WALL FINISH IS THE KEY. IN A CASE OF RERING YOU WOULD NEED CYL S WITH NO WEAR ANDROOM TO REFINISH BORES WITH CORECT STONES. MY EXP. IS HAVE MACHINIST RESURFACEWITH CORECT STONES AND PREFURABLY AUTOMATED HONE.SOME ONE LIK TED WOULD HAVE THE SPECSAND EQUE TO DO THIS. THE PAY BACK WOULD ONLY BE OBVEOUS ON THE DYNO AND HEAVEY LOADING,OR RACE TRAK USE. BUT FOR MOST OF US LESS PISTON RING DRAG AND VEREY LITLE CYL WEAR WHEN USED WITH PROPER AIR CLEANER AND SURVACE INTERVALS. JUST MYTAKE,AND INFO GLEANED FOME LOCAL EXPERTS

You are probably right.

And thats TOO much.!



  AussieBill            YYYY    Forever Y Block     YYYY

 Down Under, Australia

I read somewhere that the factory rings were made by Hastings. But I only believe 50% of anything on the Internet..

The factory rings are good parts, the top ring is chrome, I will be using a set in one of my backup race engines.

  The cast ring and  moly are about the same for bore ware but the  moly ring will  seal for a longer  period, Chrome Rings seal well but they eat up the bore!