A question for BB owners

[SwaveDave]

On the drivers side of the block, just above the Oil Pan, are Four 3/8" plugs about 6 inches apart. The passenger side doesnt have them. What is the purpose of these 4 plugs ? There is oil behind them .

Thanks , Dave

 

[JohnZ]

4-bolt blocks were threaded for external oil cooler fittings at the factory; the front hole is 3/8" NPT, and the other two are 1/2" NPT. On a 2-bolt block, only the two rear holes are drilled and tapped - the front hole is 5/16" (drilled only - not tapped) and the center hole is 3/8" NPT. One of the holes was used to install the oil filter bypass valve in the main oil gallery, then plugged.

 

[SwaveDave]

John, So then, the rear two holes could be used for an external oil cooler then ???

Thanks, Dave

 

[JohnZ]

Yes, but you'll need a special bypass valve and some other small parts (see the Chevy Power Book for details), and use minimum 1/2" I.D. lines. You can't just "hook it up" and go. A simpler approach is to use the factory adapter that sandwiches between the oil filter and the block that has the fittings and bypass valve built in; the full-fledged approach using the holes in the block is unnecessary unless the car will be road-raced.

 

[SwaveDave]

Okay. Thanks much for the into John

Dave