Cracked blocks

[forcefed6.4ford]

Yep. Got to love a guy that comes to your house with the toy box.

 

[Morgan@Midwest Diesel & Auto]

We torqued a lot of them to 325 before the 275. Now we do 250. None of ours cracked at 325. But others did. Some still cracked at 275. The castings aren't perfect. 250 is plenty. With an arp 2000 @ 250# on a 16mm stud at 4 per cylinder with the thread pitch they have it should be capable of holding way more than any sub 2000 hp engine could ever muster the cylinder pressure to stretch. (Whew long sentence) That means that the studs won't move. Still doesn't hold up for sealing surface and proper gaskets as they play a big part too. But I can tell you it would be nearly impossible to stretch an 4 arp 2000 16mm studs over the surface area of a 3.87" bore at any street drive-able power level.

I've seen at least two cracked block torqued to 275 with known good wrenches at very reputable shops and still cracked. So I can't say it's just the torque. The blocks are weak in that area and some are weaker than others.

 

[78f100]

I'm not sure if I posted this in here yet or not and don't feel like looking back to see. I am certainly not as familiar with these as Morgan and Tadd but have done lots of studs without ever having a issue. I cracked my block with elite/a1 studs at 180 or 190 ftibs I can't remember exactly what they go to now. I did it by the book and it still cracked. I was able to fix it with some paste and cooling system sealer so far.
You can bet from now on I will follow how Morgan does it in hopes it never happens again. I understand uneven clamping force is applied somewhat but don't think it is drastic enough to cause issue. I used a good tq wrench (mac)cleaned all the holes, used lots of lube, and went exactly by directions. I can't say for anyone else but for me it was not instillation error, and I doubt it was on most of the rest who had this happen. My old block has had 2 torques using the same studs, same process on it without issue. I think some of it is the actual casting and you never really know if it will happen or not till it's too late. So it's best to use caution and assume it will.

 

[B585Ford]

Has anyone who has done a lot of these ever put mics on them to see if there is much thickness difference in the weak area? Would an X-ray help to determine if you are the lucky owner of a weaker block?

 

[forcefed6.4ford]

X-ray is only good after the crack happens. There are shear wave (ultra sound for metal) metal gauges out there but I believe they are pricey.

 

[78f100]

I'm sure someone can but where they crack would be hard to measure. I will try to measure at the top of the holes on some of the blocks I have just to see if there is a obvious difference, when I have time.

 

[Stroked777]

I can't remember what I posted in this thread but my truck is a job one, studded 30k ago with arps to 275 ft lbs, I beat my truck pretty hard, (stock fuel, air and trans) and I'm still keeping my coolant level where it has been since the day it rolled out of the shop it was studded at

 

[Highroller54]

I'm no imagineer but if the blocks are cracking from the stud being bottomed out then there would be allot more broken **** then just 6.4 blocks. It has to be the great amount of pressure that a stud of that size at that torque puts on a block that was never designed to see those levels. Its also funny that only the two holes crack so does everyone only bottom out those two? Lol

 

[SVTDanny]

250 is plenty. With an arp 2000 @ 250# on a 16mm stud at 4 per cylinder with the thread pitch they have it should be capable of holding way more than any sub 2000 hp engine could ever muster the cylinder pressure to stretch.

Yes, 250 is more than enough. I assume you have an engineering study to back that up?

ARP, the manufacturer of the stud that has spent tens of thousands of dollars in R&D and thousands of hours to make the stud just recommends 275 ft/lbs because they feel like it's a good number. Not because that's what it takes to yield the stud to the point where it provides proper clamping force.

Unbelievable.

 

[TXAG07]

Yes, 250 is more than enough. I assume you have an engineering study to back that up?

ARP, the manufacturer of the stud that has spent tens of thousands of dollars in R&D and thousands of hours to make the stud just recommends 275 ft/lbs because they feel like it's a good number. Not because that's what it takes to yield the stud to the point where it provides proper clamping force.

Unbelievable.

Dude, seriously..... You've said you've had experiences working with engines and you're telling me that not once have you determined that a particular product might perform differently than for it's particular design for better or worse? I'm an engineer, and although every theory that's been proven for hundreds of years tells me something about how I should design things doesn't mean its going to work out that way in the real world. There are things such as variables, assumptions, ect that can account for anything. In this particular case and stud (arp) it seems to do its job from the 220+ ft/lbs just as Morgan said. That's from his experience. You can believe anything you want, but why not take someone's knowledge in this particular application and listen instead of trying to say they are wrong.

Sometimes you have to fly a kite in a thunderstorm to understand what the f is going on.......

 

[Highroller54]

Yes and arp has never lead us wrong before, anyone remember the fun with the 7.3's?

 

[drunk on diesel]

Yes, 250 is more than enough. I assume you have an engineering study to back that up?

ARP, the manufacturer of the stud that has spent tens of thousands of dollars in R&D and thousands of hours to make the stud just recommends 275 ft/lbs because they feel like it's a good number. Not because that's what it takes to yield the stud to the point where it provides proper clamping force.

Unbelievable.

you know what car manufacturers do after engineers design everything? they TEST them...

an engineer can come up with a desired clamping force and a torque spec required to meet that number, but those calculations don't take into consideration the REAL WORLD issues with the 6.4 block casting!!!!!

do you have a comparable real-world test study on head studs in 6.4 blocks to counter his argument? don't worry, we already know the answer.

take your literary masturbation elsewhere please

 

[SVTDanny]

I'll just throw away all the ARP torque sheets I recieve then. Obviously they are worthless if I can just make up my own torque values, as long as they "seem to work."

an engineer can come up with a desired clamping force and a torque spec required to meet that number, but those calculations don't take into consideration the REAL WORLD issues with the 6.4 block casting!!!!!

Do you really think that ARP didn't put their stud in several engines before releasing it?


Cracked blocks are a direct result of installation error. Period. Anyone that tells you differently is a fool. Keep blindly following everything you read on the internet.....

 

[jimdawg185]

This guy....

 

[drunk on diesel]

Cracked blocks are a direct result of installation error. Period. Anyone that tells you differently is a fool. Keep blindly following everything you read on the internet.....

says the guy who blindly follows everything he reads in the instruction manual.

has ARP ever issued revised torque specs for any of their fasteners?

 

[Highroller54]

Cracked blocks are a direct result of installation error.

Correct. Over stressing the block from excessive force applied but too much torque is a error. I'm glad we got threw this and you have seen the light!

 

[SVTDanny]

says the guy who blindly follows everything he reads in the instruction manual.

Following the instructions provided by the designer and manufacturer of the product. That sounds like a terribly stupid thing to do, doesn't it?

 

[drunk on diesel]

way to conveniently avoid the question...

HAS ARP EVER ISSUED REVISED TORQUE SPECS FOR ANY OF THEIR FASTENERS!?!??!

 

[Crack85]

way to conveniently avoid the question...

HAS ARP EVER ISSUED REVISED TORQUE SPECS FOR ANY OF THEIR FASTENERS!?!??!

LOL....yep

 

[SVTDanny]

way to conveniently avoid the question...

HAS ARP EVER ISSUED REVISED TORQUE SPECS FOR ANY OF THEIR FASTENERS!?!??!

Sure they have, when different lube is used. Torque is a measure of friction on the fastener. The type and amount of lube used wildly affects the clamping force provided by any given torque value.