Originally posted by mikey007:
hey, thanx alot for all the info guys. But could u "dummy" what u just said down a little. So is this a 327 or a 350, or both?
There are two (for the purposes of this discussion) types of Small Block Chevy (SBC) motors: small-journal and large-journal. From 55 to 67 the main bearing journals were 2.3" in diameter, the rod journals were 2.0 inches.
Starting in 1968 (67 for the 350) the main bearing journal size was increased to 2.45" and the rod journals went to 2.1". This is the difference between large and small-journal motors.
Going a little further, the 327 has a bore of 4.0" and a sttoke of 3.25" The 350 has the same bore (4 inches) and a 3.48" stroke. So in essence, the 327 and the 350 are the same except for the crankshaft, pistons and rods. The block is the same.
So you can have a block that is listed as either a 327 or a 350 based on the casting and stamping numbers, and either could be correct, depending on what's inside.
To make things more interesting, the 327's crank is the same as a 307 (a much lower performance motor). So you can make a 327 out of a 307 by boring it out to 4" (and hoping you don't hit the cooling jackets during the boring process) and using 327 pistons.
The same holds true for a 350: you can make it into a large-journal 327 by using a 307 crank, pistons and rods.
All of what I've written is relative to large-journal motors. The small-journal SBCs (265, 283, 302 and early 327s) use the same size main and rod journals and bearings...but the bottom end parts are not interchangeable with the large-journal motors. Other parts are.
I dunno if this has cleared things up or muddies the water. If you really wanna get overwhelmed, read thru the book, "Chevy By The Numbers 1965-1969" by Alan Colvin. There's enough stuff there to keep your head spinning for weeks. (Years in my case.)
Btw, don't get me started on 400 SBCs or 396/402/400 BBCs. That's one awful can of worms.
