Here's where we left things...
Here's where we left things last month. The main and rod bearings have been measured, the crank is in place and the main caps have been torqued. Now it's time to install the pistons and rods.
In last month's Circle Track, we kicked off a brand-new series detailing how you can save money (which can then be invested in better parts) and gain more control of your racing destiny by building your own race engine. We laid the foundation by detailing how to prep the block for machine work, install freeze plugs, measure and pre-fit the rod and main bearings, fit the rings, and install the camshaft and crank. This time around we'll complete the short-block (the block with the crank, camshaft, rods, pistons and timing set installed).
If you remember, the engine is a Chevrolet 350 based on what's typically called the "Limited Late Model" class. Flat-top pistons, 23-degree cast iron cylinder heads, stock stroke and journal sizes, dual-plane intake and a two-barrel carburetor. You get the picture. We chose this class because we believe it's right in the sweet spot where most racers live. We're not yet at the level of cost-is-no-object exotic components, but we're above the most basic level where intelligent modifications and part selection will definitely give you an advantage.
With that said, let's get back to work:
The entire rotating assembly...
The entire rotating assembly came as a pre-balanced package from JR Motorsports. The Mahle pistons, sized 0.030 over, are a relatively light 579 grams and feature Mahle's antifriction coating on the skirts.
The rods are manufactured...
The rods are manufactured by Scat (just like the crank). They use the stock journal size and are the stock 5.7 inch length. This is a no-frills rod that should still be much stronger than stock components.
JR Motorsports sent over the...
JR Motorsports sent over the rods and pistons preassembled, but we pulled them apart to inspect them and check the weights-which turned out to be well-matched from rod to rod. When assembling pistons and rods, always make sure to use plenty of assembly lube-Royal Purple's synthetic assembly lube in this case. Install the pin lock on one side and slide the wristpin in place joining the rod to the piston. One side of the rod has a chamfer on it, make sure it's oriented with the piston so that the chamfer points outward (not facing toward the other rod on the journal).
The Mahle pistons use wire...
The Mahle pistons use wire locks, which are generally better than spiral locks, which can damage the piston if the engine goes into detonation. With new engine builders, installing locks can be quite frustrating and even lead to scratched pistons if you try to get the locks into place with a screwdriver. Scratches and gouges not only look bad, but they can also create stress risers which will weaken the material. A great alternative is the Lock-In Tool, which makes installing pin locks a breeze.
To get the lock in place,...
To get the lock in place, place one edge of the wire in the groove inside the pin tower. Press the Lock-In Tool against the pin and apply pressure to slowly work the wire into the groove all the way around.
It's time to pull the caps...
It's time to pull the caps off the rods again. By this point, you should have had the rods together and apart at least twice. By far, the easiest way to do this is with a dedicated rod vise like this one from Goodson. It also ensures the rods won't be damaged. You can use an electric impact wrench to remove the caps like you see here, but don't ever use them for installation.