So how did this happen?

Posted By: Dart Racer

So how did this happen? - 01/18/14 04:33 AM

A couple of days ago I was preparing the car for the new season and discovered what I thought was a single crack in the block on the passenger side which runs from the top of the front freeze plug to beyond the top of the back freeze plug. Today while pulling the motor I discovered that the driver side is also cracked in the same place. Whoa!!!!! I consider myself lucky as the car was running fine last time out, and to think about what could have happened just sends chills down my spine.

Details: 500 Wedge all motor, 625 HP,
727, No trans brake,
motor plate with straps from the frame to the motor mount bosses on both sides.

Any thoughts so I don't have the same thing happen again, if by chance I did something wrong that I don't know about.

Thanks ole wise ones......

Posted By: bigdad

Re: So how did this happen? - 01/18/14 04:35 AM

Did you have ani freeze and did it get cold enough ?

Posted By: Dart Racer

Re: So how did this happen? - 01/18/14 04:50 AM

Quote:

Did you have ani freeze and did it get cold enough ?

I am in California and the car is kept in a 72 degree temp controlled shop.....

Posted By: Anonymous

Re: So how did this happen? - 01/18/14 05:01 AM

Don't know your setup, but torque straps to one of the mounting bosses is never a good idea.......

I don't get why the passenger side would be cracked also though....unless....do you have rigid straps on both sides ??

Posted By: MR_P_BODY

Re: So how did this happen? - 01/18/14 05:02 AM

Quote:

Quote:

Did you have ani freeze and did it get cold enough ?

I am in California and the car is kept in a 72 degree temp controlled shop.....

Do you have engine limiters on both sides(to each mount)
and does the crack start near the mount ears

Posted By: 80fbody

Re: So how did this happen? - 01/18/14 05:22 AM

Is this a filled block?

Posted By: Bigbeep

Re: So how did this happen? - 01/18/14 05:44 AM

I feel your pain!

What year block is it? I have since been told that the 66 and 67 blocks were the thinnest on the exterior casting walls. mine is a 66 casting and is filled and it is all cracked up. Beep

Posted By: Dart Racer

Re: So how did this happen? - 01/18/14 07:01 AM

[quote
Do you have engine limiters on both sides(to each mount)
and does the crack start near the mount ears

Yes, engine limiters on both sides and attach to the motor mount attachment points. Crack starts right at top of freeze plug and runs horizontally past the rear freeze plug.

Posted By: Dart Racer

Re: So how did this happen? - 01/18/14 07:03 AM

Quote:

Is this a filled block?

Yes, filled to the bottom of the freeze plugs

Posted By: Dart Racer

Re: So how did this happen? - 01/18/14 07:04 AM

Quote:

I feel your pain!

What year block is it? I have since been told that the 66 and 67 blocks were the thinnest on the exterior casting walls. mine is a 66 casting and is filled and it is all cracked up. Beep

yes, it is a 67 block. Was your block filled? And did you have torque straps?

Posted By: Dart Racer

Re: So how did this happen? - 01/18/14 07:06 AM

Quote:

Don't know your setup, but torque straps to one of the mounting bosses is never a good idea.......

I don't get why the passenger side would be cracked also though....unless....do you have rigid straps on both sides ??

Yes strap to each motor mount boss.

Posted By: Dart Racer

Re: So how did this happen? - 01/18/14 07:11 AM

Quote:

Don't know your setup, but torque straps to one of the mounting bosses is never a good idea.......

I don't get why the passenger side would be cracked also though....unless....do you have rigid straps on both sides ??

Where should they be attached? I never considered the motor mount boss wouldn't work given that's what point the factory used to hold the engine.

Posted By: OUTLAWD

Re: So how did this happen? - 01/18/14 07:26 AM

Had a 66 block that did the same thing. Rubber mounts, only 540 hp.

Posted By: MR_P_BODY

Re: So how did this happen? - 01/18/14 07:46 AM

Quote:

Quote:

Don't know your setup, but torque straps to one of the mounting bosses is never a good idea.......

I don't get why the passenger side would be cracked also though....unless....do you have rigid straps on both sides ??

Where should they be attached? I never considered the motor mount boss wouldn't work given that's what point the factory used to hold the engine.

The original mounts were rubber so it didnt slam
anything... I dont know the relationship between the
freeze plug holes and the mount ears on a big block
but if the ears are near the crank and a weak block
then MAYBE thats your problem... I have limiters
on both sides on my SB to the mount ears and havent
hurt any block... a pic would really help

Posted By: Cab_Burge

Re: So how did this happen? - 01/18/14 09:26 AM

Quote:

Quote:

Don't know your setup, but torque straps to one of the mounting bosses is never a good idea.......

I don't get why the passenger side would be cracked also though....unless....do you have rigid straps on both sides ??

Where should they be attached? I never considered the motor mount boss wouldn't work given that's what point the factory used to hold the engine.

I always use the power steering bolt hole on the water pump for my straps until I switched to elephant ears

I also ran the stock motor mounts on both sides with the straps on the left(drivers) side

I ended up with a 413 industrial block that had a crack in it, it wasn't found before all the machining was done for my 426 M.W. stocker back in the early 1980s, I ended up running that motor foor the whole year, I took the radiator cap apart so it wouldn't hold any pressure at all and drian the block bewteen races

The machine shop had found a crack cylinder beside the crack in the block but I didn't find the exterior crack before it starting leaking at the first race of the year

Posted By: Oyvind Mopar

Re: So how did this happen? - 01/18/14 10:23 AM

They are stress cracks due to the design. I read about the development of the Hemi that they had to stress-relieve the blocks (heat treat them) after casting was done to avoid this from happening when raced. A socalled seasoned (used) block is supposed to have been stress relieved due to the heat cycles. Maybe the factory solved it with adding goods on later blocks?..

Posted By: SportF

Re: So how did this happen? - 01/18/14 02:47 PM

Well, if you are making 700 foot pounds of torque, that means a foot away from the damper, you have 700 foot pounds of rotation. I am pretty sure those motor mounts will take that. Also, a block "seasons" itself after time and that stress goes away. From here I would guess the block was froze at one time and cracked it. I have seen a few blocks crack around here and that is the way it turns out. I know a lot of folks think the ice will extrude through the "frost plug" holes but that ice expands equally in every direction, restrained or not. That is my guess, and this crack worked its way out with the power you are making. An interesting experiment is to try and hammer up an old block and knock some cast iron off of it. It will surprise you how much effort that takes, IF you can do it at all. Better luck to ya in the future.

Posted By: therocks

Re: So how did this happen? - 01/18/14 02:49 PM

My 65 casting 440 block cracked between the soft plugs also.It was in for 30 years.Never dripped and never froze.At the machine shop they found the crack.Now I run my 70 block.It ran on OE mounts and wasnt making a ton of HP.Rocky

Posted By: dogdays

Re: So how did this happen? - 01/18/14 03:26 PM

Dudes, you haven't lived enough. Those are VERY COMMON cracks. They aren't from freezing. They happened even at stock hp levels. They can be pinned. Later blocks had more material added there.
R.

Posted By: Anonymous

Re: So how did this happen? - 01/18/14 03:34 PM

Quote:

Quote:

Don't know your setup, but torque straps to one of the mounting bosses is never a good idea.......

I don't get why the passenger side would be cracked also though....unless....do you have rigid straps on both sides ??

Where should they be attached? I never considered the motor mount boss wouldn't work given that's what point the factory used to hold the engine.

The original mounts were bolted to 3 points on each side....if u have rigid straps going to only one of the bosses.....that's where the problem lies imho

Posted By: MR_P_BODY

Re: So how did this happen? - 01/18/14 04:16 PM

Quote:

Quote:

Quote:

Don't know your setup, but torque straps to one of the mounting bosses is never a good idea.......

I don't get why the passenger side would be cracked also though....unless....do you have rigid straps on both sides ??

Where should they be attached? I never considered the motor mount boss wouldn't work given that's what point the factory used to hold the engine.

The original mounts were bolted to 3 points on each side....if u have rigid straps going to only one of the bosses.....that's where the problem lies imho

To me its the angle of how its loaded.. in other words
if you pull from the side of the block as in a torque
strap its not bad... but if you load from the front
of the engine as in engine limiters(limiting the
front/back movement) the load then applied to mount
ears is amplified by the 2" or so that the ears stick
out off the block and that would load the block 90*
to what it was originally designed for.... I load
the ears on my SB at a 45* angle which is 1/2 the load
on the block... but from what some are saying its
just a weak block

Posted By: 70satelliteguy

Re: So how did this happen? - 01/18/14 05:12 PM

"Dudes, you haven't lived enough. Those are VERY COMMON cracks. They aren't from freezing. They happened even at stock hp levels. They can be pinned"

Pull it out and have it pinned and welded

Mike

Posted By: Bigbeep

Re: So how did this happen? - 01/19/14 01:17 AM

I pinned mine last winter and it just moved where it would crack. Crack moved forward to the 1st and 2nd freeze plugs. I pinned it between the 2nd and 3rd. Also have a crack that runs vertical on the corner of the block on the #2 cylinder. That crack starts about a 1/2" below the top of the fill. I am cutting my loses with this block. I hate kicking money of the tailgate of my truck at the scrap yard and this got me about 6 races before cracking someplace else.

Beep

Posted By: coro500net

Re: So how did this happen? - 01/19/14 02:22 AM

Same issue on my 67 440,had it pinned and never a problem,and it is a street car.

Posted By: nss guy

Re: So how did this happen? - 01/19/14 03:57 AM

curious what the main cap webbing looks like..ie cracks, especially above #4 main.

Posted By: Cab_Burge

Re: So how did this happen? - 01/19/14 05:41 AM

I've seen several(3+) RB, 440 and 426 M.W. with cracks between the #1 and # 3 cylinders from the bottom of the cylinders into the main webs

Posted By: J_BODY

Re: So how did this happen? - 01/19/14 05:38 PM

I'm sure most are familiar with this, but here's a block without the "ribs" on the side.

...and here is the "added" material.

FWIW... I had a 69 block with the "ribs". No fill, motor plate used without a limiter for years, but later added one that attached to the 1/2" hole down near the pan rail (see pict 2). Never found any cracks, even had it checked before the last freshen (was on it's fourth...and waaayyy worn out!). Was putting down some decent power as it did run a few 9.9 passes.

Posted By: Dart Racer

Re: So how did this happen? - 01/19/14 10:29 PM

I'll post up when they get it apart if any cracks inside.

Posted By: Dart Racer

Re: So how did this happen? - 01/19/14 10:29 PM

Just loooked and my block has the ribs.....

Posted By: Dart Racer

Re: So how did this happen? - 01/19/14 10:47 PM

Couple have asked for photos. Got the engine out this morning.

Those who asked about how I was attaching the limiter bars you can see on the engine mount I made a plate to attach the bar to and the bar runs to the frame just before the radiator.

Posted By: Dodgem

Re: So how did this happen? - 01/20/14 02:37 AM

Thats a later 68 block (probably a 69 model year) those stiffening ribs were supposed to help stop that cracking between the frost plugs common on the early 68 and older Big Blocks.