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INSTALLATION INSTRUCTIONS RINGS
TOP RINGS SECOND RINGS OIL RINGS
Molybdenum faced, barrel Grey cast iron, reverse Stainless expander, circum-
lapped, ductile spheroidal torsoinal twist, taper faced, ferential type, chromium
graphite iron, phosphate zinc phosphate coated. plated rails, low radial dept
coated.
STEP 1
Install the oil rings first. Wind on the stainless
expander first with the ends pointing
down and butting.
STEP 2
Install the upper rail before installing the bottom rail. If you attempt to install the lower rail fist
the assembly will become tangled as the rail passes over the expander gap. Install the upper
rail gap about 90° counterclockwise from the expander gap. Install the lower rail with the
gap about 90° clockwise from the expander gap. The reason that rail gaps must be separate
from each other and the expander gap is to avoid overstressing of the expander. If the two
rails are fitted with their gaps in line the friction effect of the rail inners against the expander
rail support pads will cause most of the relative movement to be concentrated over a small
number of humps. This will cause the most highly stressed hump to break. Also, the expander
will either overlap or become tangled if its gap is assembled in line with either or both of the
rail gaps.
STEP 1
Install the second ring with the dot to the top of the piston. Install top ring last. If there is a
dot on the top ring, install with the dot to the top of the piston. If there is no dot, but there is a
chamfer on the inside diameter, install the chamfer to the top of the piston. If there is no dot or
chamfer on the ring, it is symmetrical and can be installed in the groove either way.
PAGE 1
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INSTALLATION INSTRUCTIONS RINGS
END GAP
ROSS RACING RINGS FOR THE TOP AND SECOND GROOVES ARE OVERSIZED AND MUST
BE FILE FITTED TO OBTAIN PROPER END GAP.
The proper amount of end gap required is directly dependent upon the amount of heat to
which the top ring in most cases should be the bore size in inches x .004. (To convert mm to
inches multiply the bore size in mm x .03937). To determine the proper end gap in the second
ring on normally aspirated engines multiply the bore size in inches x .005. It is recommended
that the second rings have more end gap than the top rings to allow any blowby gasses
passing the top rings to quickly escape to the crankcase. If the second ring gaps are set
smaller than the top ring gaps, the engine may show less leak down under static conditions!
Should the top ring land be .180 or narrower add .002 total to the above computed end gaps.
EXAMPLE: 3.625 (92mm) bore with. 150 width top land: 3.625 x .004
= .015 plus .002 for the narrow top land = .017 total end gap.
For engines that are blown, turbocharged, or run nitrous systems of more than 30 horsepower
per cylinder add .004 total to the end gaps shown above. EXAMPLE: 3.625 x .004 = .015 plus
.004 for turbocharger - .019 total end gap.
BLOCK HONING
When boring the block allow a minimum of .003 for finish hone. If finish bore size is to be
3.500, bore to dia. of 3.497, any less than this will leave boring marks remaining after honing
and will prevent proper ring seating.
USE TORQUE PLATES WHILE HONING OR THE PISTONS ARE LIKELY TO SCUFF AND THE
RINGS WILL NOT SEAL PROPERLY.
Two stages of honing are required to achieve the fine surface finish which we recommend for
Ross Racing Rings. The first stage is used to bring the bore to a size of .0005 smaller than
the finished bore size.
Honing speed should be approximately bore diameter in inches divided into 1000 (ie for 3”
bores 300 RPM and for 4” bores 250 RPM). We recommend a 30° cross hatch angle.
First stage honing should be done with a 220 grit stone and the finish stone
should be 400 grit. Use care to avoid burnishing or burning cylinders. PAGE 2
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INSTALLATION INSTRUCTIONS RINGS
CHECKING THE GROOVES
Spin all rings in grooves to be sure that the rings are free in the grooves. Check ring side
clearance with feeler gages. The top compression rings and second rings should have a side
clearance of .002 to .004 unless the pistons are gas ported (with gas ports it is permissible to
run the side clearance as tight as .0015. Ross Racing Oil Rings should have between .003
and .005 side clearance.
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. Ross Racing Top and Second Rings should have approximately
.004 back clearance. This will allow oil (which has been scraped off the cylinder wall by the
top oil ring rail) to flow radially to the oil return holes. We recommend approximately .030
back clearance with our oil rings.
Please note that all three (mm) or narrower oil rings, regardless of brand, work best with split
radius oil return holes in the pistons. All Ross Racing Pistons include split radius oil return
holes with three (mm) or narrower oil ring grooves.
End gaps in the top two rings should be
staggered approximately 180°. Lubricate
pistons and rings with a premium grade oil
of at least 20W/50 weight before installing
in the bores.
• Low viscosity monograde oil is not recommended.
• Do not use additives, either for initial lubrication or in the engine oil system,
until the rings have seated.
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