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Budget Race Engines - Build Your Own Race Engine, Part 2Completing The Foundation From the January, 2009 issue of Circle Track By Jeff Huneycutt Photography by Jeff Huneycutt
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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.  The easiest way to install...  The easiest way to install the piston rings is to lightly clamp the connecting rod in a vise to hold the piston steady. It's a good idea to wrap the rod with a shop rag to keep it from getting scratched. Also, use a ring spreader for installing the rings. You can install them by hand but they are more likely to develop a "twist" if you do. Begin with the oil ring and work your way up.  When installing the oil ring,...  When installing the oil ring, make sure to install the center expander ring first. This is because it not only acts as a separator between the upper and lower sections of the oil ring, but it also has portions that sit on the inside diameter of the rings and push them outward, which you can see here.  When all the rings are in...  When all the rings are in place, make sure none of the gaps line up. You can spin the rings until there are at least 30 degrees of separation between each of the gaps.  If the bearings aren't still...  If the bearings aren't still in place, make sure they are clean and install them now. Lubricate both halves with assembly lube. Use a thicker lube-not motor oil-to ensure the bearings will be protected during startup.  Before installing the pistons,...  Before installing the pistons, take a moment to reclean and lubricate the cylinder bores. Wipe down the bores with a rag soaked in automatic transmission fluid (ATF). This works well because the ingredients in ATF not only lubricate the cylinder walls, but they also break down any residual oils and contaminants. Make sure to turn the rag often so that you aren't simply moving contaminants from one cylinder to another.  Lubricate the piston's rings...  Lubricate the piston's rings and skirts with motor oil before installing them in the cylinder bores. Old-school engine builders will tell you to dunk the entire assembly in a bucket of motor oil, but this isn't necessary and just causes a mess.  Using a quality ring compressor...  Using a quality ring compressor will make your life a lot easier when installing pistons. If you scribed numbers on each of the rods (one through eight), drop them into the correct cylinder bore. Once the piston is in position (the valve reliefs should be toward the lifter valley), gently tap it into the hole with a clean rubber mallet until all three rings are completely inside the cylinder bore. Never use a steel hammer. If anything more than light taps are necessary, check to make sure a ring hasn't popped out between the ring compressor and the deck of the block.  Once the piston is completely...  Once the piston is completely inside the bore, you can set the ring compressor aside and push the piston in the rest of the way by hand. But before you have even installed the rod and piston, you should make sure the crank's rod journal for the cylinder you are working on is turned so it's as far away from the cylinder as you can get it. Be careful to guide the end of the rod over the journal so you don't scar the rod journal. Alternatively, you can also use a 3 or 4 inch length of plastic tubing placed over the rod bolts to protect and guide the rod end so as not to scar or scratch the rod journal.  On a Chevy small-block, the...  On a Chevy small-block, the cylinders are numbered so that all the odd numbers are on the right bank of cylinders (when looking at the front of the engine) and the evens are on the left. If you look closely, you will notice the first cylinder bore on the right is a little bit forward of the first cylinder on the left. This is why it's numbered as the first cylinder.  Now, slide the rod cap into...  Now, slide the rod cap into place. Again, make sure the chamfered side points to the outside of the rod journal. Remember, the caps always orient on the rods one way. Lubricate the threads of the rod bolts with moly lube, or extreme pressure lube, and install the nuts just tight enough so that the crank can be turned over without splitting the cap from the rod.  Your bolt manufacturer will...  Your bolt manufacturer will probably provide torque specs for the rod bolts, but the most dependable method for avoiding a connecting rod failure is to check rod bolt stretch. I'm using a gauge from ARP. Begin by zeroing out your gauge on the bolt when it's in a relaxed state.  Now torque both bolts on that...  Now torque both bolts on that rod to 10 ft/lbs less than the suggested spec and measure the same bolt again that you zeroed the gauge against the first time. Rod bolts should stretch between 0.005 and 0.007 inch. The stretch should be too low. If it is, release the tension on the bolt, increase the setting on the torque wrench and repeat the process. Aim for 0.0055 to 0.006 of stretch. If you stretch past 0.007 inch, the bolt should be considered trash.  Next, you will need to make...  Next, you will need to make sure each pair of rods on each crank journal have enough side clearance. You can do this with a dial indicator set up on a magnetic base like you see here. Hold one rod against the crank fillet and move the other back and forth. You should have at least 0.008 inch of clearance. If you don't have a dial indicator, you can also check side clearance by placing a feeler gauge between the rods.  Once all the pistons are in...  Once all the pistons are in place, you can slip the timing set on. The easiest method is to align the dowel on the camshaft so that it's in the 3 o'clock position. This will help you line up the timing marks.  Almost all timing chain sets...  Almost all timing chain sets have dots on both the crank and cam gears. When these are aligned directly across from each other, you know the cam is installed "straight up," or with zero advance or retard. Notice how this crank gear has multiple keyways to allow you to advance or retard the cam four degrees. When installing a timing set like this, it can be easy to get confused with crankshaft location. Just remember that when the number-one cylinder is at top dead center, the key on the crank will be pointing toward the number-one cylinder (as you can see here).  Once the timing set is in...  Once the timing set is in place, we can spin the rotating assembly over to make sure the rods do not contact the camshaft we installed last month. If the engine isn't a stroker, interference between the spinning rods and the camshaft is unlikely, but it's always a good idea to check anyway. During the process of installing the pistons and rods-and throughout the rest of the build-you will be spinning the crank many times. The easiest way to do this is with a crank socket like this one from Powerhouse Products.  If you don't have a crank...  If you don't have a crank socket, you can also use a large crescent wrench, which will grab onto the crank key to allow you to spin the crank. Just be careful not to damage either the snout of the crank or the key  Finally, you can install the...  Finally, you can install the rear main seal. This block was originally a one-piece rear main seal design, but it has been fitted with a two-piece seal adaptor. The two-piece design works with more performance cranks and oil pans than the one-piece blocks. In this build, we're using all Cometic gaskets. Use a thin bead of gasket sealer or silicone on the back of the seal (where it mates to the adaptor) and oil or extreme pressure lube on the lip of the seal before installing. Also, always make sure the lip of the seal points toward the interior of the engine. Finally, it's a good idea to "clock" the seal, or slide it so that the parting line of the seal does not match up with the parting line of the cap, as you can see here. This helps eliminate annoying oil leaks.  The two-piece adaptor uses...  The two-piece adaptor uses two socket-head hex bolts to fasten the cap in place. The studs you see sticking up are for the oil pan.
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