What hp are mopar 440 stock main bolts good for

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alex perini

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When is it necessary to install arp studs in the 440 lower end mains building mild street 440 will stock bolts hold up ?
 
theyre 40 plus year old stock bolts.... if you give a damn whether it blows up or not is the real decision here
 
I agree with the above..... but I have also seen many 500 - 600 hp builds survive for years of street and strip use with standard bolt on caps. The skirted bottom end of the B / RB is inherently strong.
 
The biggest improvement you can make on any stock block is main studs. The RB blocks being as weak as they are will benefit more so than most. With studs the caps are being pushed into the block instead of being pulled like with bolts. This destrsses the main area of the block where RBs have problems.
 
Pascamp said:
The biggest improvement you can make on any stock block is main studs. The RB blocks being as weak as they are will benefit more so than most. With studs the caps are being pushed into the block instead of being pulled like with bolts. This destrsses the main area of the block where RBs have problems.
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I would like to see the science of that. All a stud is is a bolt with a nut on the end instead of a hex head. They both do the same thing. No?
 
Mopar Tim said:
I would like to see the science of that. All a stud is is a bolt with a nut on the end instead of a hex head. They both do the same thing. No?
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With a bolt the torque is transfered to the block, and the bolt pulls the cap down. With studs the torque is applied to the nut, and the cap is pushed into the block.

When studs are being used you have to rehone your mains because the block is destressed and not distorted.
 
500 to 600 hp it's easy and cheap enough I should just do it for insurance I guess
 
Sorry Tim, I got interrupted.

Studs also have other advantages. The torque on a bolt only applies about 10% of it's force to clamping. The other roughly 90% is used up overcoming friction (thread engagement, bolt twist, ect). Studs not only apply way more clamping force, but the torque values are way more accurate due to the fine thread for the nut and quality of the machining. That increase in clamping force helps stabilize the block. In many cases crank walk can be completely eliminated using studs.

In some oval track classes where OEM blocks are required studs make a huge difference. The additional clamping force and destressing of the block not only let the block live longer, but can help a cast crank(lighter weight) live. Most crank failures have nothing to do with the crank. It's the block flexing that wipes the crank out. When people use a forged crank they usually don't realize that the benefit is that a forged crank can flex better than a cast crank.
 
For what it costs I always stud the mains. THe rods get beam polished and shot peened with ARP bolts. That setup will take you well over 500hp for years.
 
Pascamp said:
Sorry Tim, I got interrupted.

Studs also have other advantages. The torque on a bolt only applies about 10% of it's force to clamping. The other roughly 90% is used up overcoming friction (thread engagement, bolt twist, ect). Studs not only apply way more clamping force, but the torque values are way more accurate due to the fine thread for the nut and quality of the machining. That increase in clamping force helps stabilize the block. In many cases crank walk can be completely eliminated using studs.

In some oval track classes where OEM blocks are required studs make a huge difference. The additional clamping force and destressing of the block not only let the block live longer, but can help a cast crank(lighter weight) live. Most crank failures have nothing to do with the crank. It's the block flexing that wipes the crank out. When people use a forged crank they usually don't realize that the benefit is that a forged crank can flex better than a cast crank.
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I agree with the block flex, twist under heavy load that's why you need to run .0025 - .0030 clearance, If you run .0015 the oil gets pushed out and you get metal to metal and that's what wipes out cranks, it makes a lot of heat on the crank journal and wipes the bearing surface off.
 
Do you have to enlarge the main cap hole slightly to install studs or just line hone? Thanks!
 
cuda620 said:
Do you have to enlarge the main cap hole slightly to install studs or just line hone? Thanks!
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I've never had to. You will need to chase and clean all the threads well though as studs should bottom out in the hole. I've also seen many times where the factory didn't tap the threads all the way to the bottom. That should be addressed prior to install. Also don't forget to use the supplied lube. This cuts friction to increase clamping force.
 
Ok. I heard you had to. I’m gonna use studs even though it’s probably overkill for my build. Better safe than sorry. Thanks!
 
cuda620 said:
Ok. I heard you had to. I’m gonna use studs even though it’s probably overkill for my build. Better safe than sorry. Thanks!
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In some applications it may be necessary, but I've never had to. The registers align the cap, not the stud. I have had to enlarge holes on windage trays though, and play games with washers to get the spacing right.
 
Pascamp said:
Sorry Tim, I got interrupted.

Studs also have other advantages. The torque on a bolt only applies about 10% of it's force to clamping. The other roughly 90% is used up overcoming friction (thread engagement, bolt twist, ect). Studs not only apply way more clamping force, but the torque values are way more accurate due to the fine thread for the nut and quality of the machining. That increase in clamping force helps stabilize the block. In many cases crank walk can be completely eliminated using studs.

In some oval track classes where OEM blocks are required studs make a huge difference. The additional clamping force and destressing of the block not only let the block live longer, but can help a cast crank(lighter weight) live. Most crank failures have nothing to do with the crank. It's the block flexing that wipes the crank out. When people use a forged crank they usually don't realize that the benefit is that a forged crank can flex better than a cast crank.
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Thank you..
 
Mopar Tim said:
I would like to see the science of that. All a stud is is a bolt with a nut on the end instead of a hex head. They both do the same thing. No?
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^^^^^^^^^^^^^^^^^^
I agree w/ this . A stud stops a little of the main cap walk, supposedly.
 
I use the ARP set. It's a great upgrade for the reasons noted above. Have a shop install the studs. They may need to enlarge the holes in the caps very slightly, and the block MUST be align honed following the install.
 
You need to spend some time with the ARP catalog or on-line to see the science behind bolts/studs issue.
 
I have also used grade 9 bolts were $ is a issue, grade 8 are 150.000 psi tensile and
grade 9 are 180.000 psi tensile strength and they are about $5 ea
 
brian6pac said:
I have also used grade 9 bolts were $ is a issue, grade 8 are 150.000 psi tensile and
grade 9 are 180.000 psi tensile strength and they are about $5 ea
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Grade 9 from a good hardware store? I never thought of that...
 
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