340 or not to be....
Guest
Posts: n/a
340 or not to be....
LOL , whata schmuck, I know......
Anyway, Im curious if the bore and heads are all that made a 340 different from a 318? I know the stock stroke was the same. So theoretically I could take a good 318 block, crank, and have it bored to 4.04 and grab a set of X or J heads, and other than the block saying 318 it would be a 340???
And to that end, WHY THE HELL DO FOLKS WANT MILLIONS OF DOLLARS FOR A BLOCK JUST BECAUSE IT SAYS 340 ON IT? I mean I can get 318's and 360's a dime a dozen around here. So I suppose it boils down to a "look what I got" mentality?
Or is there something im missing? was the block lighter, will the heads not interchange? Whats the REAL deal here guys?
And ya just gotta admit, the post names catchy.........
Anyway, Im curious if the bore and heads are all that made a 340 different from a 318? I know the stock stroke was the same. So theoretically I could take a good 318 block, crank, and have it bored to 4.04 and grab a set of X or J heads, and other than the block saying 318 it would be a 340???
And to that end, WHY THE HELL DO FOLKS WANT MILLIONS OF DOLLARS FOR A BLOCK JUST BECAUSE IT SAYS 340 ON IT? I mean I can get 318's and 360's a dime a dozen around here. So I suppose it boils down to a "look what I got" mentality?
Or is there something im missing? was the block lighter, will the heads not interchange? Whats the REAL deal here guys?
And ya just gotta admit, the post names catchy.........
Mopar Lover
Joined: Mar 2009
Posts: 837
Likes: 2
From: Springfield NE
A 318 bore size is 3.91. A 340 bore size is 4.04.
I doubt you could bore ANY 318 (LA) to the size of a 340. That's .130 [thats more than an 1/8 inch!] Maybe an old polysphere could be bored that far, but I wouldn't try it. Yes the crank has the same stroke (3.31) and the main bearing diameters are the same but most 340's had a quality forged steel crank (except the 73's). Hard to find. The 360 had the larger main bearings and a 4.00 bore. Not sure if the block was any tougher. The 340 had the better flowing heads with the 2.02 intake valve. The 360 had a similar head but the intake valve size was 1.88. (mostly). The one that is really rare is the 340 T/A block. It was stronger than the standard 340 block.
I doubt you could bore ANY 318 (LA) to the size of a 340. That's .130 [thats more than an 1/8 inch!] Maybe an old polysphere could be bored that far, but I wouldn't try it. Yes the crank has the same stroke (3.31) and the main bearing diameters are the same but most 340's had a quality forged steel crank (except the 73's). Hard to find. The 360 had the larger main bearings and a 4.00 bore. Not sure if the block was any tougher. The 340 had the better flowing heads with the 2.02 intake valve. The 360 had a similar head but the intake valve size was 1.88. (mostly). The one that is really rare is the 340 T/A block. It was stronger than the standard 340 block.
Guest
Posts: n/a
340.....
So, your saying the 340 had a larger bore and better heads than a 360? So how is it only a 340? bigger bore, bigger valves, same stroke, ...... wouldnt that theoretically make it a larger displacement than a 360? Now im really cornfused.....
Mopar Lover
Joined: Jun 2008
Posts: 655
Likes: 0
From: PNW, and LOVING IT!
The 360 had a smaller bore but a longer stroke. Like the 400 vs 440. 400 has a larger bore and the 440 has a longer stroke. That is why you get more CID with a 400 block and a 440 crank. The earlier 340s had better heads than the late ( 73 ) 340s and 360s. Heads have nothing to do with CID, just bore and stroke. IIRC, the formula is .7854XBoreXBoreXStrokeX# of Cylenders. If I were you, I would find a good starter 360 and run with it!
Even better, drop a big block in that A-Body!
j
Even better, drop a big block in that A-Body!
j
Last edited by chlngr1970; Jun 12, 2009 at 12:53 PM.
Thread
Thread Starter
Forum
Replies
Last Post
strelnik
New Members
5
Mar 11, 2011 09:30 AM
