L89 427 Big Block Engine Build - Eagle Crankshaft & JE Pistons

L89 427 Big Block Engine Build Long Block Complete

Typically, the engine build-ups we do here at Super Chevy are more about the recipe and less about the procedure on how to actually build the engine. We do this because the assumption is most of you readers are seasoned builders who know how to assemble an engine (or the person putting together your motor will). We figured it was time to go into more detail on how to build the actual engine before we put it up on the dyno to see how our combination works.

Our idea is to take a very iconic motor, the L89 427 big-block, but build it with new, modern parts. No junkyard or swap meet stuff for this build-everything will be new but still retain the visual essence once you pop the hood. We know that a 427 is pretty small in today's sea of 500-inch-plus monsters, but since we are using a Dart Big M block, the motor can and most likely will be expanded to 632ci with some machine work and a new rotating assembly.

Like we mentioned, the foundation for this build is Dart's Big M block that features some cool stuff. The block is casted out of Class-32 high-nickel iron, which is stronger than the iron used in the stock blocks. It has 4-bolt ductile iron main caps with the option of billet steel for the 1,000-plus horsepower guys. The coolest feature of the block, in our eyes, is the redesigned oiling system. Instead of oiling the cam first like the stock blocks, Dart reconfigured all the oil passages and sends it to the crank first then up to the top end. This keeps the most critical part of the engine-the mains and rods, with oil.

To cap the iron block, we picked up a set of Dart's 275cc Oval Port Pro 1 aluminum heads that have many years of R&D integrated in. The heads are cast from virgin 355-T61 aerospace alloy and have a small, high-velocity port design, raised exhaust ports, improved spark plug location to produce great flow for low- and mid-range power, while still being able to breath on the big end. Plus, the Pro 1s can be used with off the shelf pistons, valvetrain components and intake manifolds.

Inside, will be a rotating assembly consisting of a crank and rod set from Eagle and JE pistons. We want this thing to sound like a street killer so we decided to test out the Big Mutha' Thumpr cam from Comp Cams for an extremely aggressive idle. There will be a lot more parts used to get this thing running, but we'll cover that next month when show how to outfit a long-block, properly break it in, and then dyno tune it. So make sure to come back next month to see how much oomph our L89 V2.0 engine produces.

To get the skinny on what goes into blueprinting, we took all our parts to Speed-O-Motive in West Covina, California. Speed-O-Motive is a full-service machine and speed shop so it has the ability to do anything we need to this engine.

The crew took us through the entire process of getting all these components correctly installed and now we are going to pass that knowledge on to you.

Hopefully you'll be able to use these checks and procedures on your next engine build or at least know what you are paying for when you have a shop blueprint your stuff.

The first step was to have the rotating assembly set to zero balance so the engine will rev nice and smooth. We had Hines Industries, the company that actually makes the balancing equipment, take our Eagle crankshaft,...
The first step was to have the rotating assembly set to zero balance so the engine will re
...Eagle I-beam rods, JE pistons, pins and rings and balance them.
Dart sends the block with a 4.250 bore that has a nice crosshatch finish. Each bore is still checked with a dial bore gauge. This measurement will let us know the piston-to-cylinder clearance and also check the consistency of the bore sizes. We have 0.0050 piston-to-wall clearance, which is right in the middle of JE's 0.0045-0.0055 recommended range for a nitrous application. Hey, juice happens.
Dart sends the block with a 4.250 bore that has a nice crosshatch finish. Each bore is sti

With all the bores checked and good to go, our technician for the day, Chuck Seib, moved onto setting the ring gaps. He slipped in the top ring and squared it with a bore insert before checking the end gap with a feeler gauge. Look to your ring supplier for proper ring gaps. Ours are from JE and they provide a formula to determine the proper gap for just about any application you are putting together like High Performance street/strip, Street Moderate, Nitrous, and so forth. We went with the Nitrous formula.
With all the bores checked and good to go, our technician for the day, Chuck Seib, moved o
Chuck ground the top ring until he had a 0.026 gap and 0.023 on the second. These gaps are a little larger then a normal street engine that would be around 0.019 and 0.020 because we are going to throw some funny gas at this thing and we need the extra clearance for the added heat expansion the nitrous will induce.
Chuck ground the top ring until he had a 0.026 gap and 0.023 on the second. These gaps are
After the ring gaps were ground Chuck slipped on the rings and staggers each end gap away from each other. There will be a diagram of this staggering provided with your pistons. To get the rings on the pistons Chuck placed the open ends in the ring groove first and then spreads the ring open as he pushes it down. This prevents the sharp point on the end of the ring from gouging the piston. That completes the pistons for now.
After the ring gaps were ground Chuck slipped on the rings and staggers each end gap away

Now with the main caps bolted on the torqued to spec Chuck mic'd the main journals.
This measurement will let us know what bearings we need once we compare it to the cranks journal size.
This measurement will let us know what bearings we need once we compare it to the cranks j
Bearings typically come in three different sizes in standard, 0.001-inch under (-1) and over (1X) sizes. We found that we needed standard bearings for our mains to give us 0.0025 inches of oil clearance, which we determined by subtracting the crank journal measurement from the main caps measurement. If we had less clearance we could use a -1 bearing that would give us 0.001 more clearance and just the opposite if we used the 1X bearing.
Bearings typically come in three different sizes in standard, 0.001-inch under (-1) and ov

Chuck is going to set the crank in so we can install a piston at each corner to check deck height. Before that all bearing surfaces are coated with assembly lube.
Chuck is going to set the crank in so we can install a piston at each corner to check deck
After carefully setting the crank in place Chuck torques the main caps from the center out.
After carefully setting the crank in place Chuck torques the main caps from the center out
Chuck uses a tapered ring compressor and the handle of a dead blow hammer to install the number 1, 2, 7, and 8 pistons. Once the piston is in a little bit he reaches back with his left hand and guides the rod over the crank.
Chuck uses a tapered ring compressor and the handle of a dead blow hammer to install the n