This 640 is for 1984–1999 Harley-Davidson® big twin models with large displacement motors with compression ratios of 10.5 - 11.5:1 or smaller motors with 11:1 - 12:1 compression ratio, does not require as much compression as the 631. For hydraulic tappet, spring spacing is required.
These camshafts are also for 1954–’84 big twins with either the Hydraulic Conversion kit or the Cylinder Head Replacement kit for panhead engines. They are also replacement parts for Flathead Power® P-Series and SH-Series engines. Since these kits and engines include 1984–’99 style hydraulic lifters, the larger late style roller diameter requires that cams designed for 1984–’99 models must be used to achieve correct valve timing.
View Cam Specs
Cam Specifications for 1954–’84 Big Twin Engines Requiring 1984–'99 Style Cams
|
| Cam |
Application
|
Generator Part # |
Alternator Part # |
Valve Timing1 Open/Close |
Valve Duration |
Valve Lift |
Lift @ TDC2 |
Spring Spacing Required |
Tappet Type Required |
| Intake |
Exhaust |
Intake |
Exhaust |
Intake |
Exhaust |
| 513 |
74"–84" Stock or low compression |
106-6028 |
106-6027 |
18°/38° |
40°/18° |
236° |
238° |
.472" |
.163"
|
.187" |
No |
Hydraulic |
| 585 |
74"–80" engines 8.5:1 - 9.5:1 CR 84" - 93" up to 8:1 - 9:1 CR |
33-5131 |
33-5109
|
20°/45° |
60°/20° |
245° |
260° |
.540" |
.172"
|
.166" |
Yes |
Hydraulic |
| 600 |
93"–103" engines 9:1 - 10:1 CR |
33-5132 |
33-5058 |
20°/55° |
60°/20° |
255° |
260° |
.554" |
.177"
|
.170" |
Yes |
Hydraulic |
| 631 |
High RPM Cam for 93"–103" Engines 11:1+ CR |
33-5078 |
33-5080 |
34°/61° |
66°/29° |
275° |
275° |
.581" |
.359" |
.204" |
Yes |
Solid or Hydraulic |
| 640 |
93"–Up Engines 10:1 or Greater Compression
|
106-4639 |
33-5108 |
25°/60° |
65°/20° |
265° |
265° |
.590" |
.205" |
.192" |
Yes |
Hydraulic |
|
1Timing designation is function of zero lash @ .053" off base circle. Lifts based on 1.5:1 Rocker Ratio. 2Lifts at TDC are measured at the valve and are for reference only. Overlap valve lifts must be checked on assembled motor.
|
