[Ieatcamaros]

Ok first off there are eight cylinders in a 302. From the factory they are bored out to 4.002" diameter. To bore out an engine is to make the diameter of the cylinder larger. For instance, .030 over would make it 4.032" diameter. The only reason for doing this is because or cylinder wear NOT to make more power. A .030 over 302 would calculate out to be a 306. 4 whole cubic inches of displacement. WOO HOO, your making some power now! The rings on the piston will wear the cylinder's diameter out larger, thus, they will not seal off. Lack of oil, hot temperatures will aid this in happening. The wear causes blow-by, poor durability, more oil consumption. The car will also blow blue smoke out of the tailpipe when the rings are shot. So you have the engine bored out, buy oversize pistons and matching rings, and you have yourself an overhauled engine. It is all about salvaging a block.

The stroke is the other part of the equation to an engine's displacement. The bore and the stroke combined make up a displacement. The stroke is the amount of travel the piston moves up or down in the cylinder. The piston is attached to a connecting rod with a wrist pin. The connecting rod is attached to the crankshaft with a bearing and a cap. Held together with two studs and nuts. The crank has an offset cast into it. A different offset for each cylinder so they can fire at different times. This offset along with the rod length is what determines the stroke. The stroke of a 302 is 3.00". The stroke of a 347 is 3.400". The increase of stroke is for making more torque. In turn it makes more hp too. A standard bore 302 with a 3.400" crank in it is a 342. Now that you have more stroke, when you bore the engine out it becomes a 347. When you want to stroke an engine, you'll need a different crank because it will have more offset or "throw" cast into it. Then if you put the same rod on it with a stock piston, you would be pushing it out of the cylinder into the head=not good. So you have to have a special length rod and matching piston. One motor where this is not the case is the 393W. You can build one of these using a stock 351W rod, 302 pistons, and an aftermarket 3.85" crank. The crank is all you have to buy.

I hope I have shed some light on this for you without confusing you. I was trying to hit the basics of this without typing way too much. I don't know what you know and what you don't. If need a better description, just ask. I am not the best teacher in the world.