I've got a 360 block that came out of an E58 1975 Dart Sport. Was cast on the night shift 11.27.1974. What are the chances it has thicker cylinder walls? Can you tell by how much it weighs? Let me know. thx matt

It is cast after the 340 production ended, the theory goes the 340 and concurent 360s used the same cylinder walls. After that they all went thin so it is well into the thinwall production time frame. That being said even if it was in the "340 wall" era I would not want to go more than .030 over without sonic testing.

How big are you going with it. Being the budget racer I am up to .030 over I don't even bother checking them, but that's me. If it keeps you awake at night have it sonic checked

X2

Early block casting number is 3418496. These are supposed to have the same water jacket as the 340 so theoretically they could go .070 or .080 over. Core shift being what it is, I would have one sonic tested before going crazy with it.

10.10.73 date Casting No. 3418496-360-10 block for mine too. Seems .060" over is no problem according to my machinist. He's seen plenty of those blocks.

My blocks casting # is 4006830-360-5. I've also got a 340 block casting # 2780930-340-6 but that block has been punched .040 already.

4006830 is the late thin wall casting. Probably should be checked at anything more than 030 over.

There was a magazine article a while back where they sonic checked several 360's from early 70's to early 90's and the readings where all over the place. I believe the thickest one they had was cast in 1978.

The block in question is too late to be a 340 core.

RE: 360 wall thickness article?: Is there an online copy that I can read? I know AndyF's article on bigblocks. Didn't know about any smallblock article.
R.

My Challenger has the original 360 from my 76 Volare. Been .060 over 20 years don't remember the exact numbers but it was plenty thick.
Doug

I have 3 "E58 motors, all out of 79 300's. Two I had sonic checked and all had thick walls ( around .200"). The E58 motor had a bunch of special parts in it. The block should be stamped 360HP with serial #. Fifth digit of the VIN should be "L" for E58 engine car. Body code plate should have "E58" stamped on it. E 58 engines also came with a windage tray ( same as early HP 340's and 360's), specially selected ( what ever that means )cast iron crank, Larger cast iron exhaust manifolds, "360 Premium engine" sticker on the valve covers. Not sure on the last item on California package cars though. Engine ID is located just below left cylinder head. Example: 9W 360HP 6345. Translates to: 9=1979, W= Windsor plant, 360HP = displacement, 6345 = date code ( Dec. 11, 1979) Above info came from printed Chrysler data. Got a problem, take it up with them.

Anything from the '70s is suspect. Quality was all over the place. Core shift is possible on any of this stuff, regardless what it's supposed to be.

I have had early blocks thin and late blocks thick, and the opposite more common. If you are spending money on a good rotating assembly I would spend the money and have your block sonic checked.

for sure, and that holds true for ANY stock block, regardless of year. IMO, 500 HP or more for any stock block is a good rule of thumb for sonic testing.

My W9 360 Dakota project block is cast January 13 1971 3418496-4-360

It was sonic checked and all 8 bores ranged from .230"-.210" on the thrust side.

We bored this block .030" over and did a fill of Hard Block up to the freeze plugs before machining.

Awesome. You should be good to go. I had a 1971 360 block out of a motor home that checked like that.

Lets say you a had a block that was .250 everywhere. What would be the maximum bore size that would be considered safe?

I would think .060 would not be a problem. Again, what kind of HP you want to push through it has a bearing on wall thickness / block rigidity.

Say 600hp