| Part No. | Models | Year | Casting No. | Description |
| 80002-37 | WLDR | 1937, 1938 and some early 1939 | 120-36 | Front Cylinder Small fins, studs for iron heads. Have taper ground cylinder bores & factory reliefs. Chamber & ports are polished. |
| 80003-37 | WLDR | 1937, 1938 and some early 1939 | 120-361 | Rear Cylinder Small fins, studs for iron heads. Have taper ground cylinder bores & factory reliefs. Chamber & ports are polished. |
| 80002-39 | WLDR | 1939 | 120-36 | Front Cylinder 1 7/16" Intake port, small fins. No longer has studs for iron heads. |
| 80003-39 | WLDR | 1939 | 120-361 | Rear Cylinder 1 7/16" Intake port, small fins. No longer has studs for iron heads. |
| 80002-39A | WLDR | 1939 | 120-39 | Front Cylinder 1 7/16" Intake port, deep fins & wide gasket area [first year]. |
| 80003-39A | WLDR | 1939 | 120-391 | Rear Cylinder 1 7/16" Intake port, deep fins & wide gasket area[first year]. |
| 80002-40A | WLDR "Special"* | 1940 | 120-39 | Front Cylinder 1 9/16" Intake port [first year], deep fins & wide gasket area, inclined valves closer bore, as later WRs. |
| 80003-40A | WLDR "Special"* | 1940 | 120-391 | Rear Cylinder 1 9/16" Intake port[first year], deep fins & wide gasket area, inclined valves closer bore, as later WRs. |
| 80002-40 | WLDR | 1940 & 1941 | 120-39 | Front Cylinder 1 9/16" Intake port, deep fins & wide gasket area, valves standard distance from bore. |
| 80003-40 | WLDR | 1940 & 1941 | 120-391 | Rear Cylinder 1 9/16" Intake port, deep fins & wide gasket area, valves standard distance from bore. |
*
1940 was the first year Harley-Davidson introduced "tilted valves"
in the W series motor. The WLDR "Special" name that resulted from
this
change is not a factory name, it was commonly used by old timers from the era
and has become the name of reference. The WLDR Special is
the only motor from the WLDR series to use tilted valves. The motor was unique
in other ways: it had special angled roller valve tappets and
angled valve tappet guides that were unique to that motor only.
All WLDRs use standard 45" intake and exhaust valves [1.62" dia heads,
45 degree seats]. Any WLDR cylinder found with big valves has
.....been modified at one point or another.
WLD, WLDD and
WR used the same casting as late WLDR cylinders [120-39 / 120-391], but they
were machined differently and had
different part numbers.
The 1939-41 WLDR
cylinders with the 120-39/120-391 casting numbers were ported and relieved.
The manifold was also ported. The 1939
WLDD and the 1940-up WLD used the same cylinder castings but they were NOT ported
or relieved nor was the manifold ported either. The
other main difference between the 1939 WLDR and the 1939 WLDD is that the WLDR
had special higher lift, longer duration camshafts and
the WLDD used standard WL cams.
Extra special thanks to Beachdog for helping in compiling
alot of the information in this chart.