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340 or 360 engine block. Have you ever hurt one #2674499
07/05/19 04:37 PM
07/05/19 04:37 PM
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pittsburghracer Offline OP
"Little"John
pittsburghracer  Offline OP
"Little"John

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I’m not talking about after you broke a rod or crank I’m talking about cracking up thru the middle of the mains like the big blocks commonly do. I personally never have knock on wood and my junk goes without concrete and I always stick to the stock main caps. Let’s hear some nightmare stories.


1970 Duster
Edelbrock headed 408
5.984@112.52
422 Indy headed small block
5.982@112.56 mph
9.42@138.27

Livin and lovin life one day at a time




Re: 340 or 360 engine block. Have you ever hurt one [Re: pittsburghracer] #2674513
07/05/19 05:09 PM
07/05/19 05:09 PM
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junction city oregon
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viperblue72 Offline
top fuel
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junction city oregon
Following! There’s a lot of talk about a stock block not handling xxx horsepower but I don’t hear of many failures. I also hear of some that have split cylinder walls. But what about the earlier 360 blocks that are thicker. Im curious what those commonly handle without failure as I have one with 360-1 heads.

Re: 340 or 360 engine block. Have you ever hurt one [Re: viperblue72] #2674518
07/05/19 05:23 PM
07/05/19 05:23 PM
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Kalispell Mt.
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HotRodDave Offline
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Kalispell Mt.
I split a 2bbl 273 block, but the rod was already knocking and I just wanted to see at that point how much abuse it could take so I raced it till it blew.

I have a nice april 1970 360 block if someone wants to try and break it thats for sale.


I am not causing global warming, I am just trying to hold off a impending Ice Age!



Re: 340 or 360 engine block. Have you ever hurt one [Re: HotRodDave] #2674526
07/05/19 05:43 PM
07/05/19 05:43 PM
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Washington
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madscientist Offline
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Yup. 14:1 on alcohol. 8000 RPM. Made it...damn I think it made it 20 hard passes. Maybe a few more. That was 1985. I was sneaking up on it for a few years and the bearings always looked like crap because the block was moving around. Had to use .0035 on the mains to keep it from snagging a bearing. That was on 20w50 in the dog days of summer and 10w40 in the spring and fall. To get the rings seal with alcohol with the limited oil choices back then, that's what you did.

Then when we put the W2 heads on it was over. IIRC it broke in the number 2 bulk head. It bent a stock 340 crank but never broke it. That's how I knew something went [censored] up.

After that, I found a reasonable T/A block that needed 8 sleeves, snatched it up. Sleeved it, used some block filler and never broke another block. Knocked some rods out, but that a whole 'nother story

Edit: That had to be 1987 as I got out of the army in early 1984 and started the project. So I killed the block in 87 and bought the T/A block right after that.

Last edited by madscientist; 07/05/19 05:45 PM.

Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
Re: 340 or 360 engine block. Have you ever hurt one [Re: HotRodDave] #2674529
07/05/19 05:44 PM
07/05/19 05:44 PM
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Eagle, Idaho
Neil Offline
The Doctor is in.
Neil  Offline
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Eagle, Idaho
Have not broken one, or seen one get broke in person.

I do know people who have broken cast 4" stroker cranks, but it's been after several seasons on full time racing.

Re: 340 or 360 engine block. Have you ever hurt one [Re: pittsburghracer] #2674537
07/05/19 06:04 PM
07/05/19 06:04 PM
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Missouri
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jwb123 Offline
super stock
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Missouri
Nope never broke a LA small block. Have blown many head gaskets, because they only have 4 bolts for each cylinder. Had a stock 70 340 4 speed dart and the clip broke on the wrist pin, cut a big groove in the cylinder, put a sleeve in it and ran it for several more years, until I blew a clutch and broke off the corner of the block when the flywheel came apart.

Re: 340 or 360 engine block. Have you ever hurt one [Re: pittsburghracer] #2674569
07/05/19 07:20 PM
07/05/19 07:20 PM
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Milwaukee WI
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TRENDZ Offline
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Milwaukee WI
Broke a first year “magnum” motor with n2o. (Talking modern era magnum) Ran ok but lost oil pressure. Put new bearings in it, still bad oil pressure. Looked at it with more detail. Found the block was cracked through the 3 center mains, from the caps to the cam bearings along the oiling holes.
“Not a carefully tuned” would be an understatement.


"use it 'till it breaks, replace as needed"
Re: 340 or 360 engine block. Have you ever hurt one [Re: TRENDZ] #2674625
07/05/19 09:55 PM
07/05/19 09:55 PM
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Romeo MI
MR_P_BODY Offline
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Romeo MI
I have broke 3 cyl walls.. 2 of them on the same hole which was sleeved
and 1 on another engine... all been on 340 blocks.. thats all I run
wave

Re: 340 or 360 engine block. Have you ever hurt one [Re: MR_P_BODY] #2674698
07/06/19 08:12 AM
07/06/19 08:12 AM
Joined: Jan 2003
Posts: 1,237
North Central, Indiana
Roughbird72 Offline
pro stock
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popcorn


72 Plymouth Roadrunner 11.08@123.25
Re: 340 or 360 engine block. Have you ever hurt one [Re: Roughbird72] #2674723
07/06/19 10:02 AM
07/06/19 10:02 AM
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Blue Ridge, VA
Plumb Wired Offline
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Blue Ridge, VA
John, I have ran both 340 & 360 blocks with lots of nitrous and never hurt one. I even ran a MP cast 3.58 stroke crank in 71 360 block, stock caps, aluminum rods and a good nitrous piston for a couple seasons early in my KOS days.

Last edited by Plumb Wired; 07/06/19 10:02 AM.

RIP Monte Smith

aka: OutlawFish
'98 Bickel Dodge Dakota PST
Re: 340 or 360 engine block. Have you ever hurt one [Re: Plumb Wired] #2674760
07/06/19 10:51 AM
07/06/19 10:51 AM
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Tulsa, Oklahoma
340Cuda Offline
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A very long time ago we took apart a AHRA Stock Eliminator type engine and the #1 main cap came off in two parts. Started running four bolt mains mostly and never saw it a again.

Once we got up to higher horsepower and high compression we started spiting cylinder walls even with "filled" blocks.

No problems to date with R blocks.

Re: 340 or 360 engine block. Have you ever hurt one [Re: 340Cuda] #2674798
07/06/19 12:10 PM
07/06/19 12:10 PM
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Springtown Pa
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Ray408G3Hemi Offline
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Springtown Pa
I never ran a SBM , my youngest son had a 93 360 Magnum block break #1&3 cylinders split and #2 Main cap pulled from the webbing, the top of the main stud on driverside still had part of the block around it. 392 (4.00X3.90) Ci 360 with 3 plates NOS I think the heads were edelbrock...I think it was a bad casted block,he thinks it was the power level... The 340 block(I think it was a 68) had the mains walk around a few times.but he never broke that one. that was a 392ci(4.06X3.79) with Shady Dell Brodix and 2 plates of NOS


1963 Thunderbolt 496FE 10.80 (still a work in progress)
1968 Mustang slow a$$ 428 FE
1971 Boss 351 Mustang 11.20@115mph
1993 Lightning 10.61 @ 129mph 408Ci A3 headed NA
1996 Viper GTS
2001 Lightning 8.99 @ 155MPH 5.4 Mod Motor
2009 Ram 9.65@144MPH 463CI G3 NA
2010 Challenger 9.91 @ 139MPH 408CI G3ci NA
2019 F150 (local dealer's Lightning package) ..11.90s

Re: 340 or 360 engine block. Have you ever hurt one [Re: pittsburghracer] #2674840
07/06/19 01:13 PM
07/06/19 01:13 PM
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pittsburghracer Offline OP
"Little"John
pittsburghracer  Offline OP
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My last Stock block ran 9.74@2860 pounds. That block was rebuilt 3 times and in need of its 4th when it grabbed a bearing and broke a rod damaging the bottom of the block. .030 (360) from day one the bores were so bad I wore out 2 new sets of stones and most of the 3rd set just to get the bores to where I would assemble it. If I thought it was worth saving I would do some bring and have a new sleeve installed but it served me well and will be going on my scrap pile.


1970 Duster
Edelbrock headed 408
5.984@112.52
422 Indy headed small block
5.982@112.56 mph
9.42@138.27

Livin and lovin life one day at a time




Re: 340 or 360 engine block. Have you ever hurt one [Re: pittsburghracer] #2675285
07/07/19 06:13 PM
07/07/19 06:13 PM
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Posts: 4,963
new jersey usa
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11secdart Offline
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new jersey usa
Yes, I broke a rod on my old backup 340 awhile back and it took out the block. Ran good 11.30s with a 557 lift cam, 9 1/2 to 1 compression and ported "J" heads , Didn't owe me anything as it served me well and already had a few rebuilds on it. Been running a 360 Magnum block and presently an R3 block every since.

IMG_1068.PNG

68 Dart 410 / 904
92 D150 original owner
21 Ram 1500 Quad Cab, Big Horn , Hemi ,4x4
23 Audi Q5
16 Honda HRV
Re: 340 or 360 engine block. Have you ever hurt one [Re: 11secdart] #2675367
07/07/19 09:57 PM
07/07/19 09:57 PM
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PA.
pittsburghracer Offline OP
"Little"John
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Originally Posted by 11secdart
Yes, I broke a rod on my old backup 340 awhile back and it took out the block. Ran good 11.30s with a 557 lift cam, 9 1/2 to 1 compression and ported "J" heads , Didn't owe me anything as it served me well and already had a few rebuilds on it. Been running a 360 Magnum block and presently an R3 block every since.




That wasn’t the blocks fault. Like I stated I’m looking for block failures like big block Mopars are known for.


1970 Duster
Edelbrock headed 408
5.984@112.52
422 Indy headed small block
5.982@112.56 mph
9.42@138.27

Livin and lovin life one day at a time




Re: 340 or 360 engine block. Have you ever hurt one [Re: 11secdart] #2675456
07/08/19 10:02 AM
07/08/19 10:02 AM
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Posts: 2,799
Connecticut
FurryStump Offline
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I have never seen a block broken on its own. Take all the rotating assembly failures out and no never seen one. I’m not sure you can take all the rotating failures out though, if the caps walk because the block is moving and takes a bearing out isn’t the block “failing”

Last edited by FurryStump; 07/08/19 10:04 AM.

best of 11.39 at 117 mph 1.60 60’. 68 340 S Barracuda Fastback F.A.S.T [IMG]http://i67.tinypic.com/2mnnnnt.jpg[/IMG]
Re: 340 or 360 engine block. Have you ever hurt one [Re: FurryStump] #2675511
07/08/19 12:29 PM
07/08/19 12:29 PM
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Washington
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madscientist Offline
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Originally Posted by FurryStump
I have never seen a block broken on its own. Take all the rotating assembly failures out and no never seen one. I’m not sure you can take all the rotating failures out though, if the caps walk because the block is moving and takes a bearing out isn’t the block “failing”


Yes. That means the block was seeing more load than it could handle.

Again, the only question this really answers is how long did it take you to FIND the crack. If you went 100 runs and found the crack, did it happen on run 99? Nope. Sure didn't. That fracture started long before it was found.

I say these cracks show up very early and then just keep growing until the expose an issue.

So no one really knows how many runs before a fracture happens. Same when you mag a crank, or rods.


Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
Re: 340 or 360 engine block. Have you ever hurt one [Re: madscientist] #2675532
07/08/19 12:54 PM
07/08/19 12:54 PM
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Posts: 4,963
new jersey usa
1
11secdart Offline
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11secdart  Offline
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new jersey usa
Sorry I guess I misread it , forgot who posted , I would have never answered.

Last edited by 11secdart; 07/08/19 12:56 PM.

68 Dart 410 / 904
92 D150 original owner
21 Ram 1500 Quad Cab, Big Horn , Hemi ,4x4
23 Audi Q5
16 Honda HRV
Re: 340 or 360 engine block. Have you ever hurt one [Re: 11secdart] #2675539
07/08/19 01:03 PM
07/08/19 01:03 PM
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Posts: 4,662
On the parachute mount
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n20mstr Offline
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On the parachute mount
OK JOHN......ILL SAY IT

YOU DONT SEE SMALL BLOCKS FAIL LIKE BIG BLOCKS.....BECAUSE THEY DONT MAKE BIG BLOCK POWER....
HA HA HA HA HA HA HA HA HA HA HA HA HA


....BAD A$$ STREET CAR.....
Re: 340 or 360 engine block. Have you ever hurt one [Re: n20mstr] #2675545
07/08/19 01:17 PM
07/08/19 01:17 PM
Joined: Oct 2003
Posts: 11,678
W. Kentucky
justinp61 Offline
I Live Here
justinp61  Offline
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Posts: 11,678
W. Kentucky
I didn't break it but feel it would've broken eventually. 360 block with a 4" crank, I ran it for five years, best was 6.57 @ 104 in a 3260# Dart. When I took it apart to freshen it up the cam and main bearings were worn odd from the back to the front. Luckily a member here called me with a R1 engine that he no longer needed.

Several years ago there were photos posted of a small block that busted a couple cylinders from top to bottom that wasn't caused by rotating assembly failure. I don't remember what site it was posted on.

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