Building Your Own Motor
Pistons
Next let’s talk Pistons, the reason we want to talk about the pistons before the rods, is because you need to figure out which Pistons you are going to use. There are a lot of choices when it comes to Pistons and a lot you need to know, before putting your money out for a set. You will need to know the bore size of your Motor and the Stroke of your Motor. You will also want to know which Heads you will be using. And you need to know the Deck Height of the Block you are using. Some years of Blocks have a higher Deck, that earlier Motors. You will have to find this out before you spend your money. Most Pistons Have a Notch in the top of them on one side, this is the side of the Piston that should go to the Toward the Front of the Motor.
Some Pistons use a Piston Rods with Pressed in Piston Pins and others use a Full Floating Piston Pins. I recommend getting the Full Floating Pistons, Rods and Pins. The reason is because there is less friction within the Pistons. The Piston Pin moves freely inside the Rod End and the Piston. The Pistons are different, because the Pistons have a groove cut in the Piston Pin Hole for a Pin Keeper in each end of the Piston so the Pin does not move out of the Piston and into the Cylinder Wall. With Press fit Piston Pins, the Pins are press fit through the Piston holes and into the Piston Rod. The Pin Moves freely inside the Piston, but not within the Rod End. This will have to be done by a machine shop.
For Racing purposes, I only recommend Forged Pistons. These are pistons that are made out of a solid chuck of high Quality Aluminum and they are machined to the right shape and size needed. Forged Pistons are mush stronger than a Cast Piston, (like the ones found in most factory motors). Forged Pistons are a must have, for Turbo or Super Charged Motors and also Motors running Nitrous Oxide (NOS). Always have new Pistons checked for cracks also.
You will have to figure out if your Motor is going to be Super Charged, Turbo Charged, Fuel Injected, or Carbureted. If your Motor is going to be under pressure like with a Super Charger or Turbo Charger you will want Lower Compression Pistons or Dished Pistons for the higher Pressures that will be produced into the Motor. If your Motor is going to be Fuel Injected or Carbureted, you will want High Compression Pistons or Domed Pistons.
You will also have to know what Cylinder Heads you are going to use, as some Aftermarket Cylinder Heads need certain Pistons to work with their heads. You will also need to know the Camshaft you are going to use. If you have a really high Lift Camshaft with a long duration Lobe design, that means you will be putting the Intake and Exhaust Valves down into the Cylinders further for longer periods of time. You may need the top of the Pistons Notched for the Valves, so they do not hit each other. All this has to be taken into consideration and checked for clearance as you go. There is a lot to know and a lot to watch out for when building a Race Motor, that is why it would be far cheaper in the long run to buy a Motor that is already built and ready to Race.
