Why did GM use the same casting for different journal size block?
#1
Why did GM use the same casting for different journal size block?
1. I am in search of a 67' 350 block (casting 3892657) for a rebuild. I have a small journal block, but need a large journal block for this app.
2. And, does someone here know the differences in this block? It was casted for 302, 327 CID engines as a small journal block and the 1st 350 usage for 67' with large journals. I haven't found literature stating the block
difference or as to why GM would have used this same casting with different size journals. In other words you can't stretch a small journal block out to large journals, which may mean GM had to cast this block differently for
the 350? More money in tooling? I am being told the 327 block is the same and the journals can be machined out to large journal size. Would love to see an engineering print of each to compare the lower casting and main
cap size.
Can someone help?
2. And, does someone here know the differences in this block? It was casted for 302, 327 CID engines as a small journal block and the 1st 350 usage for 67' with large journals. I haven't found literature stating the block
difference or as to why GM would have used this same casting with different size journals. In other words you can't stretch a small journal block out to large journals, which may mean GM had to cast this block differently for
the 350? More money in tooling? I am being told the 327 block is the same and the journals can be machined out to large journal size. Would love to see an engineering print of each to compare the lower casting and main
cap size.
Can someone help?
#2
The blocks are identical, except, during final machining at the engine plant, the crank journals were made larger for the 350. A good machine shop can enlarge the main journal bores.
The sizes are 2.30" for the early 302 & 327, 2.45" for all 350's and later 302 & 327.
The sizes are 2.30" for the early 302 & 327, 2.45" for all 350's and later 302 & 327.
Last edited by Camaro 69; 11-03-2019 at 08:40 PM.
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