How To Install 2 Piece Rear Main Seal

| How-To - Engine and Drivetrain

Rear Main Oil Seal Conversion - Sealing The Deal

Converting Your Chevy Cake To A Race-Ready Two-Piece Rear Principal Seal

There are several reasons that Chevrolet's V-8 engine package is so popular among racers and widely supported past the aftermarket. It is compact and relatively lightweight for its displacement. It has a undecayed oiling system that holds upwards well to loftier-rpm abuse. It's comparatively easy to build and notice ways to brand power. And finally, the design has remained relatively unchanged since Chevrolet first debuted its 350ci V-8 in 1968. It wasn't phased out of production until 1996, when the LS family of engines took over.

Because of the stability of the engine's pattern, the Chevy V-eight for years could be easily plant in junkyards (that'due south less true these days), and equally a result the aftermarket supported the engine with all kinds of performance parts. Because there are so many performance options for this engine-everything from oil pans to intakes-manufacturers have to keep their prices down to stay competitive, and you can build a high-ability Chevy race engine cheaper than merely nigh any other engine with equivalent horsepower.

The i matter that throws a big, fatty monkey wrench into the works is a design change to the rear main oil seal that Chevrolet'southward engineers made in '86 model yr engines. Before that, the rear main oil seal had been a 2-piece blueprint. The problem with the two-piece seal is that it tin sometimes allow oil to seep out. This really is simply a trouble when the engine is built on an assembly line; when a knowledgeable engine builder assembles the oil seal by hand with the proper precautions, an oil leak is a rarity. Withal, new models leaking oil onto the proud possessor'due south garage floor isn't something car manufacturers desire, and so the oil seal was changed to a one-piece pattern.

The jumpsuit oil seal design never caught on amidst racers. It made working on the engine slightly more than complicated and required a dissimilar pattern for the crank, cake, and oil pan. This wasn't a trouble when junkyard blocks from older models were yet plentiful and GM Performance Parts still sold new blocks with the old seal design.

That has all changed, nonetheless. GM recently sold the last of its block inventory with the 2-piece design, and there are no plans to bandage whatever more. The aftermarket, such every bit Sprint or Motown, notwithstanding produces modest-cake castings with the 2-piece rear primary seal design, simply they tend to be more expensive than the stock blocks GM sells. Thankfully, information technology's relatively easy to catechumen a block from a one-piece rear main seal design to the older two-piece style with an adapter. The adapter makes it piece of work with popular aftermarket crankshafts, oil pans, and other components. No major machining operations demand to be performed on the cake to get the adapter to fit. In addition to the adapter plate-bachelor from GM (PN 10051118), Canton (PN 21-850), and many other manufacturers-a small fixture to simulate crankshaft location is required when performing this conversion. Some engine builders, such as Keith Dorton of Automotive Specialists, who walked us through this installation process, produce their own with circular stock on a lathe, but y'all can as well purchase one from CV Products (PN CV925).

The seal adapter is a elementary aluminum design that bolts to the back of the block. A gasket goes betwixt the cake and the adapter to eliminate oil seepage. The round bar in the back is a fixture that engine builder Keith Dorton made to align the adapter when installing information technology.