From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Installation instructions for Dubois Oilproof Rings on pistons.
| Identifier | ExFiles\Box 16\1\ Scan199 | |
| Date | 9th November 1927 guessed | |
| INSTALLING INSTRUCTIONS DuBois Oilproof Rings (Trade Mark Reg.) (Patented) CAUTION On Pistons Under 3½ Inch drill 8 or more holes not less than 5/32. Larger Pistons In Proportion. The DUBOIS OILPROOF RING must be installed in the lower ring groove of the piston above the wrist pin hole where three or more ring grooves are cut in top of piston as illustrated in cuts 1, 2 and 3 with largest diameter of the oil ring to the top of the piston. To install the DUBOIS OILPROOF RING in Ford pistons or other makes of pistons which have only two ring grooves above the wrist pin and one ring groove below the wrist pin the DUBOIS OILPROOF RING must be installed as illustrated on cut 4 (in the ring groove below the wrist pin with oil groove and holes in the pistons). An oil groove must be cut below the DUBOIS OILPROOF RING (if groove is not already cut) with oil holes as shown in cuts either 1, 2, 3 or 4 to carry the excess oil scraped from the cylinder wall, by the DUBOIS OILPROOF RING back into the crank case. Any of the above form of grooves will do with oil holes leading from the oil groove through the piston. IMPORTANT If groove is machined in piston as shown in cut No. 2, care must be taken to make the upper part of oil groove a trifle smaller than diameter of piston, otherwise the oil will back up and not run into oil groove freely. If pistons do not have oil grooves and oil holes, a simple form of groove can be cut in pistons with a hand file, if lathe is not available, by filing a bevel around the lower surface of lower ring groove, and drill 8 or more holes not less than 5/32 through the piston as shown in cut No. 1. The rings should be tried in grooves before assembling to see that ring groove is a trifle deeper than thickness of ring. Many light weight pistons have a very shallow groove that require a thin ring and many cylinders have been ruined through rings not being tried in piston for diameter. The oil rings should be tried in cylinder before installing in the piston and joints filed if necessary so opening in ring has about .003 opening. MANUFACTURERS DUBOIS MACHINE COMPANY ALBANY, N. Y. | ||