S&S Cycle Prostock Racing Camshafts Part 33-5085 - Manual (Page 3)

B. After establishing the initial lobe positions,
remove cams from cam cover, then use a suitable
press and mandrel to press the lobe onto the shaft.
It is a light press fit - an arbor press works well.
Press the lobe down completely until it is fully
seated with no gap between the lobe and the
gear shoulder. See Picture 4.
3. Degree Cam Lobes and Adjusting Lobe Positions
After the initial positioning and pressing on of the
lobes, per section “C” position the cams in the engine
and perform the degree operation.
A cam degree worksheet has been included for
convenience.
NOTES:
●
Installation of S&S ® Prostock cams should only be
attempted by an experienced engine builder
● It is up to the installing mechanic to determine the
desired intake or exhaust valve opening degree point
for all lobes. See the Notes section of the included cam
degree worksheet for formulas to assist in calculations.
● Use .053” lift off of the base circle as the degree
reference point.
● S&S recommends that cams be set-up and used in the
same engine case.
● Use only light checking springs to check valve train
clearances before cam lobes are welded.
● Do not install heavy valve springs until the cams
have been welded.
● It is the installing mechanic’s responsibility to
ensure there will be no piston to valve or valve to
valve contact.
A. Degree Cam Lobes- The procedure is repeated for
each cylinder.
1. Position a degree wheel on the crankshaft and
locate the top dead center point using a
positive piston stop. After locating TDC, set the
degree wheel so that the pointer is set to 0.
2. For either the intake or exhaust lobe, rotate
the crankshaft and note the degree mark
pointed to on the wheel at .053” lobe lift on
the opening side of the lobe.
3. The difference in degrees between the
indicated opening point at .053” lift and the
desired opening point at .053 lift is how many
degrees the lobe needs to be moved, either
forward or back to place the lobe at the
desired opening point. (Opening point for
each lobe is determined by installing
mechanic, see NOTE.)
B. Adjusting Lobe Positions
1. After determining how many degrees the lobe
must be moved either forward or back,
remove the cam from the engine and adjust
the position of the the lobe. The preferred
method is to use a special tool such as the
A.R.T. Sportster
® and XR 750 Cam Lobe Degree
Tool. See Picture 5.
3
Picture 4
Picture 5
CAUTION