Caution – S&S Cycle Cylinder Heads for Harley-Davidson Twin Cam 88 Engines User Manual

Page 4

Insufficient clearance between piston domes and cylinder
heads or piston domes and valves will cause damage to
pistons and cylinder head components.

Repeat procedure to check rear piston to cylinder
gasket surface relationship.

Check valve pocket fit.

NOTES:
G Valve pocket reliefs in stock Harley-Davidson

pistons are

smaller than those in S&S

pistons. Valve to piston clearance

should be checked if S&S heads are used with Harley-
Davidson

pistons and high lift cams. If S&S 79cc heads have

not been decked, valve to piston clearance is normally
adequate with cams such as the S&S 585G, with TDC lifts of
up to .186”/.179”. If cams with higher TDC lifts are used,
clearance must be checked.

G If S&S heads are used with S&S pistons no valve to piston

clearancing is normally required.

G If S&S heads are decked, valve to piston clearance should

be checked. If Harley-Davidson

pistons are used with

decked S&S heads, valve pockets must be modified in
nearly all cases.

With cylinders and pistons installed, turn engine
over until piston in front cylinder is at top dead
center.

Paint area around valve pockets on pistons with
machinist’s blue.

Place valves in cylinder head leaving off springs
and retainers. Place head on cylinder and
secure with one bolt.

Lower valves until they contact piston. Rotate
valve, marking painted area.

Remove head and check points of contact. Valve
should fit in valve pocket machined in piston dome.

NOTES:
G S&S recommends a minimum of .060” clearance between

intake valve and piston valve pocket recess, and .080”
between exhaust valve and piston valve pocket recess at
piston TDC.

G When checking valve to piston clearance pushrods must be

adjusted so the hydraulic piston in tappet is bottomed in the
tappet bore or on the HL

T washer if used. This insures that

tappets can not bleed down so valve position will be
accurate for clearance check.

Insufficient clearance between piston and valves may cause
them to contact each other during operation resulting in
damage to piston and valve train components.

If insufficient clearance exists, remove piston and
machine or grind valve pocket until head of valve
fits flush with proper clearance.

Repeat procedure for other cylinder head.

Check Valve to piston clearance at TDC.

Spread layer of putty into valve pockets in both
pistons.

Assemble cylinder heads and bolt on cylinders with
head gaskets in place. Install rocker covers and
pushrods. Adjust pushrods so the hydraulic piston
in tappet is bottomed in the tappet bore or on the
HL

T washer, if used. This insures that tappets can

not bleed down, so that valve position will be
accurate for clearance check.

Turn engine over in normal direction of travel two
complete revolutions.

Disassemble engine and check thickness of putty in
valve pockets.

If insufficient clearance exists, machine or grind
piston until proper clearance is achieved.

Disassemble top end and clean all parts for final
assembly.

Remove cylinders and install piston rings and wristpin
clips per S&S Piston Instruction Sheet 51-1028.

Coat piston skirts with engine oil and install cylinders.

NOTE - Stock Harley-Davidson

Twin Cam 88

cylinder heads

require two long and two short head bolts per cylinder. Stock
short head bolts can not be used with S&S cylinder heads for Twin
Cam 88

. The design of the S&S cylinder heads requires the use

of four long head bolts per cylinder. All head bolts are the same
length. Stock long head bolts can be used with stock length
motors, but the short head bolts must be replaced with long
head bolts Engines with longer than stock cylinders require four
special length, long head bolts per cylinder.

Clean threads of head bolts and cylinder studs. Spin
each head bolt down on its respective stud to be sure
threads are clean and free of contamination.

Install head gaskets dry. S&S 3

⁄

” bore heads gaskets

require O-rings around the cylinder head locating
dowels similar to stock head gaskets. S&S 3

⁄

” and 4”

bore head gaskets do not use O-rings around cylinder
head locating dowels.

Place one or two drops of oil on threads and under the
head of each head bolt just prior to final assembly to
reduce friction and insure accurate torque readings.
Bolt heads on cylinders. Tighten bolts in stages using
crossing pattern. See Figure 2.

CAUTION

Rear Head

Front Head

Top View
Driveside

Camside

Figure 2

S&S Head Bolts

Stock Head Bolts

Stage 1

8 Ft.-Lbs.

7-9 Ft.-Lbs.

Stage 2

18 Ft.-Lbs.

12-14 Ft.-Lbs.

Stage 3

Turn additional 90˚

CAUTION