What Defines a 4.1 Production Block

REDS HOT AIR

Buick Tweaker
my factory 85 ttype block is that way 20 bolt and has 3.8 and 4.1 on the back .. I was going to sonic test it but never got around to it
 

Daniel Jost

Squirtin six
Ok so it is thought to be a 85 block then, can this be made into 4.1? I thought the 4.1 was to the bottom right but i guess im wrong... I still haven't checked my other parts matching block that is sittting around from my 6/85 grand national 20 bolt pan. oh that block is stamped 84 to, ill have pics tonight
 
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