S&S Cycle Valve Spring Kit 106-6398 for 1936-47 Harley-Davidson Knucklehead Big Twin and S&S KN-Series Engines - Manual (Page 2)

2
Valve Spring Specification Chart
Installed Height 1.315” ± .005”
Seat Force 158 lb
Open Force at max lift 348 lb
Maximum Valve Lift
.480”
1. S&S valve spring kit 106-6398 for 1936-’47 Harley-Davidson
knucklehead big twin engines and S&S KN-Series engines is
designed to be used with stock valve cover tins or with S&S die-
cast alloy “tins”. Each application requires a different installation
procedure and a few different parts. For either installation, not all
parts in the kit will be used.
2. Machine stock valve guides. This kit is not compatible with stock
valve guides. If using stock valve guides, the top portion above
the flange must be machined to the dimension shown in Figure 1.
Compatible guides are available from S&S.
3. Installation with S&S die-cast alloy ‘tins”
a. Install valve guides in cylinder heads without tins. S&S tins are
not held in place against the heads by the valve guide, as in
installations with stock tins.
b. Confirm and Adjust Spring Installed Height
i. Temporarily install valve, S&S alloy tin, lower gasket, bottom
collar, top collar and top collar keepers. Do not install seal or
valve springs. See Figure 2.
NOTE: If valve guide holes in cylinder heads are damaged, S&S has
oversized guides available. Ream hole to the next oversize.
.800”
Figure 1
Keepers
Top Collar
Inner Spring
Outer Spring
Lower Collar
Shim
Seal
S&S Alloy Tin
Gasket
S&S Valve Guide
Figure 2
ii. Pull the top collar tightly against keepers to seat them in
top collar. Measure the distance between the top of the
valve guide and the bottom of the top collar. This distance is
the valve free travel and must be .060” more than the valve
lift of the camshaft to be used. See Figure 3
iii. Measure the distance between the top spring seating
surface of the bottom collar the bottom spring seating
surface of the top collar. See Figure 3. This is the spring
installed height.
iv. Refer to the Valve Spring Specification Chart. If installed
height is more than 1.320” place a shim under the bottom
collar to reduce installed height. If installed height is less
than 1.310”, valve seat must be ground to increase valve
stem protrusion.
v. Normally the intake valve will not require a shim, and the
exhaust valve will require one.
c. Once spring height is confirmed, reassemble with seal and
valve springs as shown in Figure 2. Coat both sides of the
bottom gasket with Permatex® Right Stuff® sealant.
4. Installation with stock steel tins
a. Install gasket, tins, and valve guide as shown in Figure 4. Coat
both sides of the gasket with Permatex® Right Stuff sealent
before installation. The valve guide holds the tins in place
against the cylinder head when stock tins are used.
Figure 3
Spring Installed Height
Valve Free Travel