Do early 360 blocks have thicker cylinder walls??

[femtnmax]

Were the early 360 blocks cast with 340 cylinder wall cores?  The result being the cylinders are bored to 360 specs, but have enough wall thickness to have been bored to 340 specs.
If this is true, I could build a 360 with extra thick cylinder walls.  Maybe this is not necessary for mostly street use, and I would be only boring 0.030 over std.

[Changin Gears]

I have checked this using "shade-tree" methods.  Looking through the freeze plug opening of '72 and '77 360 blocks, I measured much less space for water to flow between the cylinders on the early block.  Don't remember the numbers (20 years ago) but the early block had alot more meat.

[vinb]

Best way to tell is have the block sonic tested at your machine shop.....

[bb71challenger]

I have always heard they were thicker as well. Never had it verified though. I know there were thick main web casting 400's that were cast in a certain time period in '71 so it is not uncommon.

[71chally416]

Supposedly the earlier 360 motors were cast with 340 cores, but I wonder if that is true or not because I've seen a few early 360 blocks split the bores with just .030" over bores. The thickest block I ever had checked was a '78 400 BB. It's a good idea to sonic test any block you intend to invest money in before you start.

[HP2]

AndyF of AR Engineering and Steve Dulcich have both done research in to this claim and not found enough consistentancy in it to substantiate it as fact. Like 71chally416 said, later blocks can be as thick or thicker than some earlier blocks. The bigger issue would be which core plug iwas used duringthe castin, and is it going to provide the most consistent wall location. I forget the exact way to tell this, but it is cast in to the side of the block.

[moper]

All the "good" blocks are myths. Not because the factory didnt design them, or because of cicrumstance in core paterns (the early 360 myth).. But because Mopar castings sucked. It was poor execution. The 360s used the 340 cores, but the cores are usually not placed perfectly or moved, so the reality is there are thin spots in almost every block. The "230" cold weather 400 blocks are the same thing. Find a 230 block with thickjer walls thruout and you found a zebra with no stripes. It happens, but not often. Certainly not enought o get big money for them unless they come with a reliable sonic test. The bets bet is to take any block and have it sonic tested. One of the thickest 360s I've tested is in the shop now... it has walls as thick as .250 on the major thrusts. It's an '89 LA roller cam version.

[bb71challenger]

From the pics I have seen and from what I have seen of my own "230" its not the cylinder walls that are thicker, its the main webbing on the mains.

[moper]

It's both. But it's what you cant see that makes them no better. All 400s have the best main structure, the 230s goa  litle further. But if the bores split main integrity means little.