Ross metric/gas nitride piston rings / Ross piston rings / Racing pistons, rings & components / Racing rotating parts & components / Racing engine / Racing / Shop

Ross metric/gas nitride piston rings

Top rings are plasma moly inlaid and barrel lapped for long life and quick seating. All Ross top rings are ductile and can be twisted at least 180 degrees and back numerous times without fracturing. Top rings are symmetrical, can be fitted in the groove either way and are coated with zinc phosphate to improve initial scuff resistance. Radial thickness on all Ross moly top rings in bore sizes from 2.756 through 3.494 (70 mm through 88.75 mm) is .125. All rings above bore size 3.499 (88.9 mm) are SAE “D” wall, except .043 compression rings.

Second rings are cast iron reverse torsion twist. The torsioning is obtained from the bevel on the inner lower edge. Other performance advantages are conformability to cylinder wall, good wear resistance, and a specific OD shape that will encourage downward oil scraping and minimize upward scraping. Ross second rings are also zinc phophate coated. Radial thickness on all Ross moly second rings in bore sizes from 2.756 through 3.494 (70 mm through 88.75mm) is .125. All rings above bore size 3.499 (88.9 mm) are SAE “D” wall.

Metric/gas nitride piston rings

Bore inches:	Bore mm:	Size:	Part no:	Ring material & discription:
2.283	58.00	1.0,1.2,2.5	XC58	Chrome Steel, Taper Face Napier
2.559	65.00	1.0,1.2,2.8	XC65	Chrome Steel, Taper Face Napier
2.598	66.00	.031,.031,1.5	XA66	Chrome Steel, Taper Face Napier
2.598	66.00	1.0,1.2,2.8	XC66	Chrome Steel, Taper Face Napier
2.618	66.50	.031,.031,1.5	XA66.5	Chrome Steel, Taper Face Napier
2.638	67.00	.031,.031,1.5	XA67	Chrome Steel, Taper Face Napier
2.638	67.00	1.0,1.2,2.8	XC67	Chrome Steel, Taper Face Napier
2.658	67.50	.031,.031,1.5	XA67.5	Chrome Steel, Taper Face Napier
2.677	68.00	1.0,1.2,2.8	XC68	Chrome Steel, Taper Face Napier
2.736	69.50	1.0,1.2,2.8	XC69.5	Chrome Steel, Taper Face Napier
2.756	70.00	1.2, 1.5, 2.8	R2759	Ductile Moly
2.756	70.00	1.0,1.2,2.8	XC70	Chrome Steel, Taper Face Napier
2.776	70.50	1.2, 1.5, 2.8	R2779	Ductile Moly
2.785	70.75	1.2, 1.5, 2.8	R2788	Ductile Moly
2.795	71.00	1.2, 1.5, 2.8	R2798	Ductile Moly
2.795	71.00	1.0,1.2,2.8	XC71	Chrome Steel, Taper Face Napier
2.815	71.50	1.2, 1.5, 2.8	R2818	Ductile Moly
2.835	72.00	.031,.031,1.5	XA72	Chrome Steel, Taper Face Napier
2.835	72.00	1.0,1.2,2.8	XC72	Chrome Steel, Taper Face Napier
2.854	72.50	1.2, 1.5, 2.8	R2857	Ductile Moly
2.864	72.75	1.2, 1.5, 2.8	R2867	Ductile Moly
2.874	73.00	1.0,1.2,2.8	XC73	Chrome Steel, Taper Face Napier
2.894	73.50	1.2, 1.5, 2.8	R2897	Ductile Moly
2.904	73.75	1.2, 1.5, 2.8	R2907	Ductile Moly
2.913	74.00	1.2, 1.5, 2.8	R5012	Ductile Moly
2.943	74.75	1.2, 1.5, 2.8	R2946	Ductile Moly
2.953	75.00	1.2, 1.5, 2.8	R5015	Ductile Moly
3.010	76.45	1.5, 1.5, 2.8	2M6198-10	Cast Moly
3.010	76.45	1.5, 1.5, 3.0	2M6198-10	Cast Moly
3.012	76.50	1.0,1.2,2.8	XC76.5	Chrome Steel, Taper Face Napier
3.032	77.00	1.0,1.0,2.0	XG77	Gas Nitride, Taper Face Napier
3.051	77.50	1.5, 1.5, 3.0	R3054	Ductile Moly
3.051	77.50	1.0,1.2,2.8	XC77.5	Chrome Steel, Taper Face Napier
3.061	77.75	1.5, 1.5, 3.0	R3064	Ductile Moly
3.071	78.00	1.0,1.2,2.8	XC78	Chrome Steel, Taper Face Napier
3.071	78.00	1.0,1.0,2.0	XG78	Gas Nitride, Taper Face Napier
3.100	78.75	1.5, 1.5, 3.0	R3103	Ductile Moly
3.110	79.00	1.0,1.2,2.8	XC79	Chrome Steel, Taper Face Napier
3.110	79.00	1.0,1.0,2.0	XG79	Gas Nitride, Taper Face Napier
3.130	79.50	1.0,1.0,2.0	XG79.5	Gas Nitride, Taper Face Napier
3.140	79.75	1.5, 1.5, 3.0	R3143	Ductile Moly
3.150	80.00	1.5, 1.5, 3.0	R5030	Ductile Moly
3.150	80.00	1.0,1.2,2.8	XC80	Chrome Steel, Taper Face Napier
3.150	80.00	1.0,1.0,2.0	XG80	Gas Nitride, Taper Face Napier
3.179	80.75	1.5, 1.5, 3.0	R3182	Ductile Moly
3.189	81.00	1.5, 1.5, 3.0	R5033	Ductile Moly
3.189	81.00	1.0, 1.2, 2.8	RN3192	Gas Nitride, Taper Face Napier
3.189	81.00	1.0,1.2,2.8	XC81	Chrome Steel, Taper Face Napier
3.208	81.50	1.0,1.2,2.8	XC81.5	Chrome Steel, Taper Face Napier
3.209	81.50	1.5, 1.5, 3.0	R5034	Ductile Moly
3.209	81.00	1.0, 1.2, 2.8	RN3212	Gas Nitride, Taper Face Napier
3.218	81.75	1.5, 1.5, 3.0	R3221	Ductile Moly
3.228	82.00	1.5, 1.5, 3.0	R3231	Ductile Moly
3.228	82.00	1.0, 1.2, 2.8	RN3231	Gas Nitride, Taper Face Napier
3.228	82.00	1.0,1.2,2.8	XC82	Chrome Steel, Taper Face Napier
3.248	82.50	1.5, 1.5, 3.0	2M4745-20	Cast Moly
3.248	82.50	1.5, 1.5, 3.0	2M4745-20	Cast Moly
3.248	82.50	1.0, 1.2, 2.8	XX82.5	Gas Nitride, Taper Face Napier
3.258	82.75	1.5, 1.5, 3.0	R3261	Ductile Moly
3.268	83.00	1.5, 1.5, 3.0	R5039	Ductile Moly
3.268	83.00	1.0, 1.2, 2.8	RN3271	Gas Nitride, Taper Face Napier
3.268	83.00	1.0,1.2,2.8	XC83	Chrome Steel, Taper Face Napier
3.297	83.75	1.5, 1.5, 3.0	R3300	Ductile Moly
3.307	84.00	1.5, 1.5, 3.0	R5142	Ductile Moly
3.307	84.00	1.0, 1.2, 2.8	RN3310	Gas Nitride, Taper Face Napier
3.307	84.00	1.0,1.2,2.8	XC84	Chrome Steel, Taper Face Napier
3.312	84.12	1.5, 1.5, 3.0	RS-1001	Ductile Moly
3.327	84.50	1.5, 1.5, 3.0	R5044	Ductile Moly
3.327	84.50	1.0, 1.2, 2.8	RN3330	Gas Nitride, Taper Face Napier
3.346	85.00	1.0,1.2,2.8	XC85	Chrome Steel, Taper Face Napier
3.347	85.00	1.0, 1.2, 2.8	RN3350	Gas Nitride, Taper Face Napier
3.366	85.50	1.5, 1.5, 3.0	R5047	Ductile Moly
3.366	85.50	1.0, 1.2, 2.8	RN3369	Gas Nitride, Taper Face Napier
3.376	85.75	1.5, 1.5, 3.0	R5148	Ductile Moly
3.376	85.75	1.0, 1.2, 2.8	RN3379	Gas Nitride, Taper Face Napier
3.386	86.00	1.5, 1.5, 3.0	R5049	Ductile Moly
3.386	86.00	1.0, 1.2, 2.8	RN3389	Gas Nitride, Taper Face Napier
3.386	86.00	1.0,1.2,2.8	XC86	Chrome Steel, Taper Face Napier
3.396	86.25	1.0, 1.2, 2.8	RN3399	Gas Nitride, Taper Face Napier
3.406	86.50	1.5, 1.5, 3.0	R5150	Ductile Moly
3.406	86.50	1.0, 1.2, 2.8	RN3409	Gas Nitride, Taper Face Napier
3.425	87.00	1.5, 1.5, 3.0	R5152	Ductile Moly
3.425	87.00	1.0, 1.2, 2.8	RN3428	Gas Nitride, Taper Face Napier
3.425	87.00	1.0,1.2,2.8	XC87	Chrome Steel, Taper Face Napier
3.445	87.50	1.5, 1.5, 3.0	R3448	Ductile Moly
3.445	87.50	1.0, 1.2, 2.8	RN3448	Gas Nitride, Taper Face Napier
3.445	87.50	1.0,1.2,2.8	XC87.5	Chrome Steel, Taper Face Napier
3.465	88.00	1.5, 1.5, 3.0	R5055	Ductile Moly
3.465	88.00	1.0,1.2,2.8	XC88	Chrome Steel, Taper Face Napier
3.484	88.50	1.5, 1.5, 3.0	R5056	Ductile Moly
3.494	88.75	1.5, 1.5, 3.0	R3497	Ductile Moly
3.504	89.00	1.0,1.2,2.8	XC89	Chrome Steel, Taper Face Napier
3.524	89.50	1.0, 1.2, 2.8	RN3527	Gas Nitride, Taper Face Napier
3.533	89.75	1.5, 1.5, 3.0	R5061	Ductile Moly
3.543	90.00	1.0,1.2,2.8	XC90	Chrome Steel, Taper Face Napier
3.543	90.00	1.0, 1.2, 2.8	XX90	Gas Nitride, Taper Face Napier
3.552	90.20	1.5, 1.5, 3.0	R5062	Ductile Moly
3.572	90.70	1.5, 1.5, 3.0	R5163	Ductile Moly
3.607	91.60	1.0, 1.2, 2.8	RN3610	Gas Nitride, Taper Face Napier
3.617	91.80	1.0, 1.2, 2.8	RN3620	Gas Nitride, Taper Face Napier
3.622	92.00	1.0,1.2,2.8	XC92	Chrome Steel, Taper Face Napier
3.625	92.00	1.5, 1.5, 3.0	R3627	Ductile Moly
3.632	92.25	1.2, 1.2, 3.0	RS-1003	Ductile Moly
3.642	92.50	1.0, 1.2, 2.8	RN3645	Gas Nitride, Taper Face Napier
3.642	92.50	1.2, 1.2, 3.0	RS-1004	Ductile Moly
3.661	93.00	1.0,1.2,2.8	XC93	Chrome Steel, Taper Face Napier
3.662	93.01	1.5, 1.5, 3.0	ROSS3662	Ductile Moly
3.662	93.01	1.5, 1.5, 3.0	ROSS3662	Ductile Moly
3.740	95.00	1.5, 1.5, 3.0	R3745	Ductile Moly
3.750	92.25	1.5, 1.5, 3.0	2M4942-STD	Cast Moly
3.750	95.25	1.5, 1.5, 3.0	2M4942-STD	Cast Moly
3.760	95.50	1.0, 1.2, 2.8	RN3763	Gas Nitride, Taper Face Napier
3.780	96.00	1.0, 1.2, 2.8	RN3783	Gas Nitride, Taper Face Napier
3.812	97.00	1.5, 1.5, 3.0	R3816	Ductile Moly
3.818	97.00	1.2,1.5,4.0	XH97	Ductile Moly
3.937	100.00	1.5, 1.5, 3.0	R5068	Ductile Moly
3.937	100.00	1.5, 1.5, 3.0	R5168	Ductile Moly
3.937	100.00	1.2,1.5,4.0	XH100	Ductile Moly
3.976	101.00	1.2,1.5,4.0	XH101	Ductile Moly
3.977	101.00	1.5, 1.5, 3.0	R3980	Ductile Moly
4.000	101.60	1.5, 1.5, 3.0	R5070	Ductile Moly
4.000	101.60	1.2, 1.2, 3.0	RGN4042	Gas Nitride, Taper Face Napier
4.000	101.60	1.5, 1.5, 3.0	RS4003	Ductile Moly
4.000	101.60	1.2, 1.2, 3.0	RGN4007	Gas Nitride, Taper Face Napier
4.010	101.85	1.2, 1.2, 3.0	RGN4014	Gas Nitride, Taper Face Napier
4.015	102.00	1.2,1.5,4.0	XH102	Ductile Moly
4.020	102.10	1.5, 1.5, 3.0	R4025	Ductile Moly
4.030	102.40	1.5, 1.5, 3.0	R4035	Ductile Moly
4.030	102.40	1.5, 1.5, 3.0	R5073	Ductile Moly
4.030	102.40	1.2, 1.2, 3.0	RGN4032	Gas Nitride, Taper Face Napier
4.030	102.40	1.5, 1.5, 3.0	RS4035	Ductile Moly
4.035	102.49	1.2, 1.2, 3.0	RGN4037	Gas Nitride, Taper Face Napier
4.040	102.60	1.5, 1.5, 3.0	R4045	Ductile Moly
4.040	102.61	1.2, 1.2, 3.0	RGN4047	Gas Nitride, Taper Face Napier
4.040	102.60	1.5, 1.5, 3.0	RS4045	Ductile Moly
4.060	103.10	1.5, 1.5, 3.0	R4065	Ductile Moly
4.060	103.12	1.2, 1.2, 3.0	RGN4062	Gas Nitride, Taper Face Napier
4.060	103.10	1.5, 1.5, 3.0	RS4065	Ductile Moly
4.065	103.25	1.2, 1.2, 3.0	RGN4067	Gas Nitride, Taper Face Napier
4.070	103.38	1.2, 1.2, 3.0	RS-1008	Ductile Moly
4.070	103.38	1.2, 1.2, 3.0	RGN4072	Gas Nitride, Taper Face Napier
4.080	103.63	1.2, 1.2, 3.0	RS-1009	Ductile Moly
4.080	103.63	1.2, 1.2, 3.0	RGN4082	Gas Nitride, Taper Face Napier
4.125	104.77	1.2, 1.2, 3.0	RGN4127	Gas Nitride, Taper Face Napier
4.130	104.90	1.5, 1.5, 3.0	RS-1010	Ductile Moly
4.130	104.90	1.2, 1.2, 3.0	RGN4132	Gas Nitride, Taper Face Napier
4.135	105.03	1.2, 1.2, 3.0	RGN4137	Gas Nitride, Taper Face Napier
4.145	105.28	1.2, 1.2, 3.0	RGN4147	Gas Nitride, Taper Face Napier
4.155	105.54	1.2, 1.2, 3.0	RGN4158	Gas Nitride, Taper Face Napier
4.160	105.66	1.5, 1.5, 3.0	RS-1011	Ductile Moly
4.160	105.79	1.2, 1.2, 3.0	RGN4168	Gas Nitride, Taper Face Napier

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Technical information & support:

Ross piston ring installation instructions

Ring grooves

Ross Racing Pistons with engine bore sizes of 3.500" (90mm) and above can be machined for any popular ring combination at the time of manufacture.

All compression ring grooves at ROSS are machined to the Society of Automotive Engineers (SAE) D-Wall specifications (except dykes rings which have a radial thickness of .170"), unless the customer requests otherwise, or ROSS supplies the rings.

The radial thickness can easily be determined by using the following formula:

Radial Thickness = Bore Diameter divided by 22
For example: 4.250" bored divided by 22 = .193"
The radial thickness of a 4.250" bore D-Wall ring is .193"

This is the standard depth used by leading ring manufacturers such as Childs and Albert, Speed-Pro, and Total Seal. ROSS STRONGLY recommends that you have us supply the rings for all custom pistons that are manufactured for a bore size of 3.500" (89mm) or smaller. If you insist on supplying the rings, you must give us the ring width and radial thickness on all three rings. In lieu of this information we can not accept “stock” or ring manufacturers part number.

Ring Side: (or lateral) clearance is the measurement of the space between the sides of the piston
groove and the ring.

Unless otherwise ordered, Ross will machine all pistons for a side clearance of .002" to .004". Some engine builders prefer to have us reduce the side clearance (especially with gas ported pistons), however under no circumstances do we recommend less than .001".

Ring Back Clearance:

can best be measured by pushing the ring into the piston ring groove until it bottoms against the root of the groove.

The amount that the face of the ring is below the ring lands is the ring back clearance. It should not protrude beyond the lands when the ring is bottomed in the groove. All Ross compression ring grooves are machined for approximately .004 back clearance unless otherwise ordered. Ross will machine special groove widths or depths at no additional cost.

Ring spacing

On all Ross Custom made pistons, you may specify the amount of spacing between the ring grooves.

In most instances, moving the rings up higher (thin lands) on the pistons will allow the pistons to be lighter, as the side mill cut can then be wider. Care must be taken not to make the ring lands too narrow (especially the top land) as detonation or high cylinder pressure can break thin lands. We feel that in most instances the customer should “trust our judgment” about the ring spacing.