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Boring A LA 360

JudeDodge

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I've tried to find online how far one could bore out an 360 but all that I can find are a whole bunch of "maybe this" "maybe that". No affrimitive answers. And do to covid I can't talk with the people at the shop. I would really like your guys advice and any other 360 suggestions.
 

LocuMob

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How far are you wanting to bore it out? General limit is .060" over. What are your plans for the engine?
 

65 sporty

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Read this stuff

Mopar Engine Platforms – 318, 360

Depending on the year it looks like it should be sonic checked to go to .060
 

richard d woolsey

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big article on big blocks in mopar action about buying/using a sonic checker to measure cyl wall thickness. very informative. i know this is sb but a little info is always helpful. ordered a sonic checker off ebay last night. will be very helpful at swap meets i think.
 

LocuMob

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It's always a good thing to check the block before spending money to build it. The shop I worked at magna fluxed most blocks that came through the door, the lead machinist did it so he never had to hear anyone bitch about his work. When I came back a couple years later, and only one new machinist, the magna flux machine was never used. Basic visual check was all anyone did after that. Shame, have the equipment, I'd use it. Too bad I didn't know anything about engines back when, I had the shop to myself at night if I wanted.
 

7mopar

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My one son just recently spent 9G on an engine the find the block that he paid to have checked had a crack when placed on the dino.
That is why it's necessary to find a shop with a good rating.
The shop he used is now facing a class action.
 

JudeDodge

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Thank you 7mopar for the advice. Sorry to hear about the engine. But I have a shop that my family has trusted since the '80's
 

Scoots

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My ole Direct Connection bible says a "no date code" 360 is the very first casting in 71 based off the 340 so the water jackets are even farther from the cylinders than a post 71 block. They show taking a first run block past .100 boring.
 

7mopar

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I also remember that early casting having cooling problems do to lack of coolant around the cylinders. Of course that was a long time ago.
 

Scoots

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I also remember that early casting having cooling problems do to lack of coolant around the cylinders. Of course that was a long time ago.
I believe that, probably why they made a whole new casting late 71. I had a no date code 360 sitting around for years, got tired of moving it so it went to scrap. :-(
 

volaredon

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someone would have put that block to good usage, should have offered it for sale.
on another note, not related to a 360 but a slant6 I built about 30 years ago, I discovered a crack after it was assembled and running.... after the machine shop bored it and hot tanked it... wasn't very happy.
I am building another slant 6, block and crank machine work done, but head still at machine shop....... the machine shop I used then, went away because the owner got old and retired..... this wasnt the only engine I had taken there back then, but the only engine that I had any issue with from there. With the present build I mentioned to the current machine shop what happened to that other /6 that I did and showed him about where the crack was in that engine, (below the freeze plugs just above and along the pan rail at the front of the block) and just to at least "spot check" this one with dye pen crack checker, he sent this recent block to a bigger machine shop and had the whole block baked, shot peened and magnafluxed on a bigger scale/ it came back as "good. I haven't seen the bill yet (will get it, when they finish the head work) to see how much that machine shop operation added to the bill. he just told me how much I owed him for block and crank work, I paid him that much so far
 

7mopar

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A crack that low on a /6 block I would have just welded shut and went on. Just under the head bolts would be the worst spot. We have put them back together filling the hole the number six rod exited taking the starter out.
 

volaredon

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I drove that car for a while, and kept an eye on the fluid level /but unfortunately it got wrecked so all I was able to get from it was the head and the rest got crushed. So that made that crack a non issue
 

LocuMob

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We have put them back together filling the hole the number six rod exited taking the starter out.
That's how I received my slant six in my Dart. Piston sticking out of the block of still on the con rod. Thought the trans was good until I touched the starter, and it fell off.
 

AJ.

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I bored my 71 to 4.04 and change. Goes like a scalded cat/ no leaks.
But I just gotta say, that there is no significant power to be found at these small bore increases. I just did it so I could call the engine a stroked 340, (4.04 @3.58=~367 cid); cuz everybody is always going on about how "you shouldda built a 340". See,at the carshows, it's OK to have a stroked 340 but not OK to have a 360 ; insane I know......... and don't even mention 367. Even tho a 367 is ~8% bigger than a 340, seems nobody gets that, always with the 340 ugh.
KB 107s are over 200grams lighter than the stock 340 forged slugs, and the rods are the same. So the rebalanced and hyperized 360 revs hyper-fast, and even at 7000 is not yet at max-recommended piston-speed.. My dial-type rev-limiter is usually set to 7200, and I usually shift at 7000, even with a small cam. But you know....
sometimes I twist the dial up a lil.....lol.
Happy HotRodding
 

7mopar

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Yes this can all get insane. I refuse to bore anything that doesn't need it. Like that little bit really makes that much difference. Stroke, pistons, rods and other components will make a bigger bottom end difference. All one really needs to do is look at modern stuff.
 
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