Why do they make cranks for a 6" rod(small block chevy).will a 5.7 rod crank work with 6" rod (a 5.7 rod crank is lighter) rod lenght has more to do with the piston i.e. comp height than the crank? please you pro's tell me if I'm thinking wrong. I do love this site. :shock:
Correction.....
The taller counterweights would hit the bottom of the piston skirts, not the rod.
You can use a 6inch rod on a 5.7 crank but you can't use a 5.7 rod on a crank designed for a 6inch rod.
Correction.....
The taller counterweights would hit the bottom of the piston skirts, not the rod.
You can use a 6 inch rod on a 5.7 crank but you can't use a 5.7 rod on a crank designed for a 6 inch rod.
You get the prize for the correct answer!!! 8) 8) 8)
The counterweights for a 6" rod crank will hit the skirts if a 5.7 rod is used, however you can run 6" rods on a 5.7 rod counterweight. The reason for two different? Larger counterweights are easier to balance, less heavy metal. Larger strokes make this even worse, limiting the counterweight size. The 3.875 crank would need to have the counterweights turned down, then balanced with more heavy metal to use 5.7 rods.