How to Build a Stroker Motor
Stroker Motors make more power than stock ones because a stroked crankshaft has a greater distance from the crank centerline to the centerline of the rod journals where the bottom end of the connecting rods are bolted on. This increases the lever arm for the forces which are generated by the burning fuel and transferred into the downward force on the pistons and transferred through the connecting rods. Additionally, the displacement of the engine is increased because the swept length the piston travels in the cylinder bore is longer.
Building a stroker motor is not for the automotive novice or the faint of heart, but starting with the common 350 CID Small-Block motor should enable success because the parts and methodology are tried and true over the years. It is very unlikely that a person would choose the stroker route and not be including a number of additional engine modifications along the way. The common language from at least one vintage hot rod song includes the words "Stroked and Bored", which indicated that the diameter of the cylinder bores and pistons were also increased.
Building a stroker motor requires a bit more machining on the bare block, and care should be taken in selecting a shop that has demonstrated experience in this type of build. The block will require a good bit of machining around the lower end where the piston rods rotate, as they will be swinging on larger radius and would most likely be hitting a stock block in these areas. The lower area of the cylinder walls will also normally need additional clearance. The crank will either require extensive modification or a stroker crank should be ordered from a reputable manufacturer.
The parts to build a stroker 350 should all be readily available, and some places market a kit which includes all of the needed parts. Remember that in the process it is necessary to do quite a bit of studying to determine the correct pistons, camshaft and other bits which make up the assembled block. In order to get the available horsepower out of the stroker, it would be normal to use modified heads which have been flow-benched and include the largest valves that can be used.
Several years ago, while participating in the Woodward Cruise, I happened to be alongside a Nova that was normally driven a quarter-mile at a time but had been let out for the day. The lettering on the side said it had a stroker motor, and the rubber that was deposited on the road by the slicks as the open headers thundered off confirmed that claim.
