Our first series of “What I Learned Today” was popular enough that EngineLabs editor Greg Acosta asked us to pull up another ten items from our storehouse of that with which we’ve struggled with over the past five decades in our quest with cars. Not all of the learning moments are necessarily bad situations, but all were lessons learned. Some are more observations on ways to build your next engine or accidents that could have easily been avoided with a little bit of care and attention to detail. All are intended to assist you in your next engine-related adventure. It’s a great, fun process and even more enjoyable when the pitfalls and disasters are averted. Remember, as Henry Ford is quoted as saying, “The only real mistake is the one from which we learn nothing.” Happy Trails.
Why One-Piece Rear Main Seal SBCs Are Awesome
There are still a lot of people who are hard-core small-block Chevy guys. And to this day, the most popular small-block out there has to be the 383. For those who may only be conversant with LS engines, a 383ci small-block Chevy uses a 400 crank, cut down to 350 main sizes, to fit in a 350 block while employing the 400’s longer 3.75-inch stroke. This is an easy way to gain cubic inches and make torque. This is exactly the opposite of a new idea. It’s been around for nearly 40 years. But let us present a new twist on this traditional idea.
There are several good reasons for considering a one-piece rear main seal small-block Chevy for your next 383ci street engine. Chevy converted to the one-piece rear main seal around 1986 and incorporated several new features in the redesign. Not only do these engines use a superior rear main seal that has been proven to be far less leak-prone than the old 2-piece versions, but they also feature a one-piece oil pan gasket that saves time over the original, complex, four-piece small-block Chevy pan gaskets.
Even better, these later model blocks include fixtures in the lifter valley to accommodate a factory-style hydraulic roller cam and lifters. These blocks allow using the more affordable factory hydraulic roller lifters retained by dog bones and the bolt-down, eight-point, spring steel retainer called a spider. Plus, all these engines are fitted with a factory retainer arrangement that uses a stepped camshaft nose instead of the early flat nose arrangement. More importantly, this eliminates the hassle of custom setting cam endplay that is required when retro-fitting a roller cam into the earlier small-blocks engines.
Furthermore, these one-piece rear main seal blocks will use the factory-style hydraulic roller lifter that is much more affordable than most aftermarket retro-fit link bar lifters. This means using a hydraulic roller cam in a small-block Chevy just became far less expensive compared to the cost of retrofitting a roller to an early two-piece rear main seal block.
For a conservative street engine (500 horsepower and less), these newer factory one-piece rear main seal blocks offer multiple advantages. Keep in mind that the one-piece crankshaft will require a dedicated flexplate or flywheel because the bolt pattern is different. But that still allows the builder an incredible amount of flexibility in choosing his components while saving money over a two-piece rear main seal engine.
These later, one-piece rear main seal engines can still be found in boneyards as they were used in trucks from 1986 up until GM converted to the LS engines in 1999. Beyond 1999, the one-piece rear main seal engines were used in larger Express vans and utility vehicles up through 2003. These blocks are also used in several current Chevrolet Performance crate engines.