Is the dowel pin required? I ordered a set of dowel pins off EBay that said they are the correct GM part number but they are way too small. Even though the GM parts list calls out a dowel pin that is 0.312 in diameter under that number, the ones I got are way smaller..

 

I went to my machine shop guy but we couldn't fine one to fit. He said that none of the cranks he has in his shop (including a 3.1L crank) don't have them. He said they are only for alignment and do not add any strength to the crankshaft bolts. He said the newer big block engines which come from the factory only have roll pins for alignment and no dowel pins. So, going to put mine back together without one but still aligned properly.

 

When I bought my GM Goodwrench 350, it did not come with a crankshaft pin. I contacted Summit and they said that GM stopped installing the crankshaft pin. They said to install the flexplate/flywheel aligning the holes. Install the bolts and torque to spec. I guess GM discovered that the shear strength of the flexplate/flywheel bolts is enough even without the pin.

Fred