Lingenfelter 4 in Stroke Crankshaft Clearance Guide v2.0 - Manual (Page 5)

Page 3
Step 3
: Since the windage tray has been moved down to make room for the increased
stroke of the crankshaft, the oil pan will not sit flush against the engine due to interference
between the windage tray and inside ribs on the oil pan.
: To allow the oil pan to sit flush against the engine block, the inside ribs and bosses
must be ground a minimum of 0.250in using a grinding tool, such as a dremel. The inside
ribs that need to be ground away are indicated by diagonal black lines, shown in figures 6,
7 and 8.
Figure 6 Figure 7
Figure 8
Note:
The oil pan shown in the figures is from a
C5 Corvette. Similar clearancing is re-
quired on other GM oil pans.
You can also send your oil pan to LPE for
this modification or purchase a modified
oil pan from LPE.