What year 360's have the "thicker bore"

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krazykuda

krazykuda

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What year 360's have the "thicker bore". I know the 71's were thicker, how long did they make them?
 
my 71 wasn't much bigger , are you thinking of the 318 police intercepter ??

I am not sure
 
They are all a crap shoot. This year or that year myths and wives tales are rampant on the subject of cylinder thickness. One of the best (thickest) 360 blocks I have was .040 over when I sonic checked it. Best advice I have to give is sonic check 'em or roll the dice.
 
You are gonna run into a whole lot of mishmash varied opinions on here. There is no real general consensus on what's the thickest. So I'd go out on a limb and say, the blocks are as varied as the opinions. You can end up with a buttload of core shift or they have a thin spot or you can hit a homerun and get a badass block. I would say the magnums have alot more solid metalurgy compared to a 70's block so I'd bank my money on one of those
 
The "rumor" used to say 1976 or earlier, especially 71-74 blocks, had the same casting cores as 340's and therefore had thicker walls. I never went past .030 on mine.
If you go to a 4.060 bore after sonic testing it does make a 372 or close to it.
I did luck into a 360 4V factory shot peened crank they used to talk about in a 4 star rebuild I bought cheap.
Instead of the usual AAWJ foundry marks this one has CMD cast into it. Supposedly because they were made by the same foundry that made some GM cranks. I wouldn't kill myself looking for one though.

Magnums and any LA blocks from EFI vehicles usually have less wear due to precise fuel metering. And due to the fact they are 20 years+ newer!
 
I have a 70 year casted block that was sonic tested by cornell engine balancing of ft myers that is one of those never see it again was told the block could see .200 over no problem.It is currently a fresh .100 over unassembled 4.0 stroke new pistons h beams .685 roller set up completly squared line honed and reciprocating components balanced for sale in my package deal but may separate for a decent offer there is aset of biba brodix heads that need some repairs with titanium valves and some other things I would like to see 4000. for all the crank is new as well and I have all the rings already file fit and all full groove bearings to go with the head machinist Buddy found this on accident and set it aside for his dad and now I got it through a package deal among other Items I already have a couple other engines so I wouldnt miss it
 
Always been told 71-74 360s are thicker. Or the lower the casting number the better the casting. ? never seen anything proving one way or the other. Have seen late 70s blocks bored .060 over w lots of meat left.
 
4spdragtop said:
Karl, I was at a car show and heard Herb Mccandles say 75 and older blocks had the thicker bore.
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That's what I'm trying to determine. I have a bunch of 360 blocks, I'm wondering which ones have the stronger bores. Mine are spread out through the 70's, some early, some middle, some late....
 
swinger340 said:
Always been told 71-74 360s are thicker. Or the lower the casting number the better the casting. ? never seen anything proving one way or the other. Have seen late 70s blocks bored .060 over w lots of meat left.
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you hit the nail on the head with the lower the casting #, the better the casting. The reason being is that the mold will be less likely to have core shift with the first few pours versus the last few. I believe a mold is only used 6-8 times then they chuck it for a new one. Someone feel free to correct me if I'm wrong, but that is what I have researched over the years.
 
I can tell you the outcome of me personally sonic testing over 100 blocks, but every time I bring it up, I get argued down so screw it.
 
The only ones I know of are supposed to be cast before the end of '71. So casting dates of 70-71 "should be" assuming they are not core shifted. I have only tested one, dated 6/71, and it was shifted and no better than anything else later or Magnum. The best and most consistent castings I've found have been the 80s vintage LA 360s, the later the better. I've also heard the later ones got better iron, but are thinner. Magnums would reinforce that IMO. They seem pretty good and don't wear much.
 
RustyRatRod said:
I can tell you the outcome of me personally sonic testing over 100 blocks, but every time I bring it up, I get argued down so screw it.
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Rusty, you know I value your opinion very much here. Especially when you have cold hard evidence and not talking from out your ***. So with that said give me your scoop on this topic.......
 
The 88 and up roller blocks usually are quite good in regards to casting quality and thickness.
 
71Scamper said:
Rusty, you know I value your opinion very much here. Especially when you have cold hard evidence and not talking from out your ***. So with that said give me your scoop on this topic.......
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IIRC, when I talked to him 2 years ago when he did it, he said the Magnums aren't as thick as the 70's block. But that's just what I recall with my s**t memory.

I found a lil more on his findings, but not much.

"We've sonic tested several 70-73 date coded 360s and all of them measure about twice as thick as the later 70s engines. Hensley Motorsports sells 408 strokers based on .090" over 318 blocks so obviously, it can be done. We have a Dakota Ultrasonics tester that cost about 2500 bucks and it's accurate. So far the rumor seems to be holding up"
 
The old mopar performace books claim up to about 1974 casting has the 340 cyl thickness. That said it's still best to bore only enough to clean up .020 or .030.
 
Thanks guys. I have a few 360's sitting around and want to know which ones had the thicker bores.
 
Have them sonic tested. Even a quick couple spots in each hole is enough to give you an idea of which are thicker.
 
krazykuda said:
Thanks guys. I have a few 360's sitting around and want to know which ones had the thicker bores.
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You have to sonic test them. Saying that this vintage 360 was "as thick as the 340's" dont mean nuttin. Some of the Worst block I have ever had the displeasure of dealing with were 340 blocks, core shift was bad back 40+ years ago. The newer blocks are way better. Better castings, better quality control, better machines and less human influence. If I had my choice out of any block laying around would be the Magnum blocks. They may not have as high a Nickle content, but the core shift is minimal and the blocks are more true.
 
Don't put too much faith in the Dash one (360-1 vs 360-8) blocks being better either. As previously stated, the only way to know for sure is with a sonic test.
 
As nearly everyone said it's a crap shoot. I have a 73 block in my car and it sonic checked nice and thick but had some core shift so my builder recommended I not go over .060" max. I just went .030 over which was enough to clean it up and gives some room if I ever need to bore it again.
 
Also, did any of the 360s suffer from the dreaded oversize lifter bores? I have a 340 block sitting here just rusting...............................
 
67Dart273 said:
Also, did any of the 360s suffer from the dreaded oversize lifter bores? I have a 340 block sitting here just rusting...............................
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If it's worth the money, they can be sleeved and redrilled. Don't forget to drill for the oil galley also.
 
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