Crankshaft Swap

[62CometISON]

Hello All,

I have a 1962 Comet with a 170 engine. I have an opportunity to purchase a 200 crankshaft from an early engine with only 4 mains like my 170. Basically I would be stroking the 170. Since the rods are the same lenght between the two engines, I would think the crank would work. One concern would be if the pistons are different between the 170 and 200 in as far as pin locations or vertical dimensions. I realize that the pistons are different diameters and have different tops (the 170s are flat tops). I was wondering if anyone has done this swap or has an ideas of any pitfalls to trying this.

Thank you.

 

[Invectivus]

It's my understanding that the increased throw on the crank will make it contact the edge of the thinner 170 block. One of the changes to the 200 was as I recall a wider crank cavity.

 

[62CometISON]

Thank you for the information Invectivus.

 

[rbohm]

8) you would also have to change the pistons as there is not enough room between the stock 170 piston and the cylinder head if you use the 200 crank. remember 1/2 the stroke difference between the two engines is .093" (3.126-2.94)/2. and that is about .050" too much. even using a later felpro head gasket with a .053 compressed thickness you are still about .025" too tall. and while you can mill the .025 off the top of the piston, you still have to deal with the compression ratio increase. if you choose to do this, make your calculations very carefully. by the way, you only gain about 18ci by using the 200 crank in the 170 block. unless you are willing to do the needed work to make sure everything clears, its better to just buy a 200 and be done with it.