Editing Oiling system Chevy V8

==Overview==
One plug that can be easily forgotten is the plug located "under" the rear main cap (as viewed with the engine block on an engine stand in position to install the plug). Without the plug, the oil will not be filtered. 

==Plug dimensions and part numbers==
===1985-back with 2-piece rear main seal===
The plug is a 1/2" OD (0.520”-0.536" OD x 0.300" deep) steel expansion plug. GM part number is 3701638 (Pioneer EPC-87, Dorman 555005). The passageway can be tapped for a 1/4” NPT plug; this requires a long tap to reach the area that needs to be threaded. 

===1986-up with 1-piece RMS===
Some engines used a steel ball instead of a cup plug. These engines are the 1986-up 1-piece RMS blocks including the Gen 2 LT1. These blocks can’t be easily tapped for a 1/4” NPT plug, the hole is smaller than the 1/2" ball or cup plug used in 1985-back Gen I SBC blocks with 2-piece RMS. The ball can be replaced with a cup plug; the cup plug part number for these '86-up 1-piece RMS blocks is Pioneer '''EPC108'''. 

==Checking block for plug==
If there is any question whether the plug is in place inside an assembled engine, a straight piece of wire can be used (like piece of brazing rod) to check the depth of the plug in the block. By going down the oil sender hole at the rear of the block, the plug should be located between 8-3/8" and 8-1/2" down. If the rod extends down further, that would indicate the plug is missing.

{|
|[[File:Sbc oil plug rear main 2.jpg|thumb|left|500px|Oil filter bypass plug location]] <br style="clear:both"/>
|[[File:Oil plug under main cap.jpg|thumb|left|415px|Plug location details]]
|}