348 Engine Block

M

Maldonado

Member
As per Tech spec's, the 348 Block bore is 4.125"and the 409 is 4.3125" bore size, so My question is : Can the 348" block be bored out to 4.3125 to accept large 409 pistons or not ? in other words, is it possible to get a 409" engine from a 348" one by replacing the 348" crankshaft for the 409" (3.50" stroke) one and bored the 348" block out to 409" size ? Just let me know...!!!

Thank you,
MALDONADO
Brasil - South America:) :D :cool:
 
Bungy

Bungy

Well Known Member
Supporting Member 3
Some 348 blocks can be bored out to a 409 std bore size but most can not. You will have to first sonic check the block to determine the cylinder wall thickness. The best 348 blocks for this are casting number 3857655 These are the later blocks that have thicker walls but even these must be checked before that much boring is done. If you are looking for extra cubic inches. Your best bet would be to stroke it with a 396/427 or 454 crankshaft.
 
M

Maldonado

Member
Hello Bungy......thanks for the help, but let me know if the 396,427 or 454 crankshaft main journal, is it the same size as the 348 - 409 ones ? And the con rod journal....is it the same one too ? Just let me know...!

Thank you very much,
MALDONADO
Brasil - S. America:D :cheers
 
oil4kids

oil4kids

Well Known Member
crank cutting

If you use the 396 427 crank you have to cut the mains down to the standard W size of 2.5 inch. The bbc crank is 2.75. Also you must cut the snout of the crank to 1.25. Also the thrust area in the back of the crank has to be reduced to 2.92 thrust area from the bbc of 3.95. Leave the con rod journals alone.

If you use a 454 crank then you can also use the small block 400 damper as it is simular in weight to the 454 external balance. You also must align and grind a new keyway in the bbc crank for the lower timing gear. A good crank machinist would check every thing before cutting the crank. You have to message the block and oil pan for the 454 crank.The 348 oil pan will not work at all. And depending on the connecting rod your using, you may have to grind some material off.
 
M

Maldonado

Member
Crank cutting

hi oil4Kids....Mark,

Wow......,it's nice to hearing from you my friend ! Make sure that I have appreciated your post reply and its KNOWHOW about these engines and at the same time I realized you do know deeply these ones. Thanks again for the great help !

Keep in touch my bud,
MALDONADO
Brasil - S. America:) :D :D
 
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