scrappie

Is there any difference between the quality or anything from 68-72 455 short blocks. Is there any year that is better than the others? How do you tell year of short block if they are all 396021 F ?

captjim

The term "short block" infers the block with pistons, rods, crank, and cam. There are differences between those. However, as far as the bare block goes, very little difference, if any.

oldstata

X2.
And if it's has all rotating assembly Main difference would be pistons. 68-70 higher compression not positive on actual numbers but 71-72 are dished for lower compression / emissions. I have read that 73-75? Have better pistons that they made the emission changes to the heads but don't know for sure

pogo69

I'm not sure how you could determine what blocks heads manifolds have higher nickel contents...but someone probably does

2blu442

For years I'd heard that the F blocks were better than the Fa blocks. But reading through posts on this site I've come to the conclusion that's more of an urban myth. Some of the later 455 blocks are not drilled for the Z-Bar pivit, so if you want to use a manual transmission with this motor that would be something to look for.

On that note, be aware that most crankshafts are not drilled for the pilot bearing and input shaft of a manual transmission. You can have a machine shop cut that on a lathe for you and there's a couple posts on the site showing the details for this hole.

The later blocks have deep dish pistons, but if your going to rebuild it you can put in the pistons for whatever compression ratio you want.


John

MDchanic

It's been done. Here.

The answer is "Not much."

It's a myth.

- Eric