General ARP Torque Recommendations
This guide explains ARP’s general torque recommendations for bulk fasteners when using ARP Ultra-Torque fastener assembly lubricant. It also explains why lubricant, fastener material, thread size and installation instructions all matter when trying to achieve the correct clamp load.
Torque Is Not The Same As Clamp Load
Torque is the twisting force applied to a fastener during tightening. Clamp load is the tensile preload generated in the fastener as it stretches and clamps the joint together.
The purpose of applying torque is to achieve the correct clamp load. This is why lubricant, thread condition, washer condition, surface finish and installation procedure are so important. Two fasteners tightened to the same torque can produce different clamp loads if friction is different.
ARP’s general torque recommendations are intended to produce a clamp load approximately equal to 75% of the fastener’s yield strength when using ARP Ultra-Torque fastener assembly lubricant.
Always lubricate before applying torque. ARP torque values are based on the use of the specified lubricant. Dry threads, dirty threads, different lubricants or damaged washers can significantly change the clamp load achieved at the same torque value.
General ARP Torque And Clamp Load Table
The following table lists general torque recommendations using ARP Ultra-Torque fastener assembly lubricant. Torque values are shown in ft-lb. Clamp load values are shown in pounds.
| Thread Major Diameter | Fastener Tensile Strength | |||||
|---|---|---|---|---|---|---|
| 180,000 psi 1,241 MPa |
190,000 psi 1,310 MPa |
220,000 psi 1,516 MPa |
||||
| Torque w/ ARP Lube |
Clamp Load |
Torque w/ ARP Lube |
Clamp Load |
Torque w/ ARP Lube |
Clamp Load |
|
| 1/4" | 12 | 3,492 | 14 | 3,967 | 16 | 4,442 |
| 5/16" | 24 | 5,805 | 28 | 6,588 | 32 | 7,371 |
| 3/8" | 45 | 8,622 | 50 | 9,782 | 55 | 10,942 |
| 7/16" | 70 | 11,880 | 80 | 13,470 | 90 | 15,060 |
| 1/2" | 110 | 16,391 | 125 | 18,515 | 140 | 20,639 |
| 9/16" | 160 | 21,220 | 180 | 23,944 | 200 | 26,668 |
| 5/8" | 210 | 26,372 | 240 | 29,756 | 270 | 33,140 |
| M6 | 11 | 3,359 | 13 | 3,814 | 15 | 4,269 |
| M8 | 24 | 5,801 | 28 | 6,581 | 32 | 7,361 |
| M10 | 54 | 9,970 | 62 | 11,305 | 70 | 12,640 |
| M11 | 72 | 12,184 | 82 | 13,961 | 92 | 15,738 |
| M12 | 98 | 14,472 | 112 | 16,949 | 125 | 19,425 |
| M14 | N/A | N/A | 184 | 22,771 | 205 | 25,730 |
| M16 | N/A | N/A | 244 | 29,664 | 272 | 33,519 |
Torque values are shown in ft-lb. Clamp load values are shown in pounds. For Newton-metres, multiply the ft-lb value by 1.356.
How To Use This ARP Torque Table
Identify the fastener thread size
Start by finding the thread major diameter in the left-hand column. The table includes common imperial sizes from 1/4" to 5/8" and metric sizes from M6 to M16.
Confirm the fastener tensile strength
Move across to the correct tensile strength column. This table covers 180,000 psi, 190,000 psi and 220,000 psi fasteners.
Use ARP Ultra-Torque lubricant
These torque values are based on the use of ARP Ultra-Torque fastener assembly lubricant. Changing lubricant changes friction, and changing friction changes clamp load.
Check the ARP kit instructions
For head studs, main studs, rod bolts and application-specific kits, always check the instructions supplied with the kit. Specific instructions override general torque recommendations.
Why Lubricant Changes Torque Readings
A torque wrench does not directly measure clamp load. It measures the turning force applied to the fastener. A large portion of that force is consumed by friction in the threads and under the bolt head, washer or nut face.
When friction is high, less of the applied torque becomes useful clamp load. When friction is more controlled and consistent, the same torque value can produce a more predictable preload.
This is why ARP specifies lubricant. Using ARP Ultra-Torque helps produce more consistent torque readings and clamp load compared with dry assembly or uncontrolled lubricant choice.
Dry Threads
Dry threads usually create more friction. This can reduce actual clamp load even when the torque wrench shows the correct number.
Incorrect Lubricant
Different lubricants have different friction characteristics. Substituting lubricant can change the clamp load produced at the same torque.
ARP Ultra-Torque
ARP Ultra-Torque is designed to provide consistent fastener preload when used with ARP’s recommended torque specifications.
General Torque Values vs Kit-Specific Instructions
The torque table above is for general information and bulk fasteners. It should not be treated as the final authority for every engine installation.
Many ARP kits are supplied with application-specific instructions. These instructions may account for the fastener type, material, washer design, thread engagement, component material and the specific joint being clamped.
Do not ignore the supplied ARP instructions. If the instructions packaged with a specific kit use a different torque value, tightening sequence, lubricant recommendation or stretch specification, follow the kit instructions.
Common Mistakes When Torquing ARP Fasteners
Using the wrong lubricant
Torque values are lubricant-specific. A torque value intended for ARP Ultra-Torque should not be assumed correct with oil, anti-seize or dry threads.
Ignoring thread condition
Dirty, damaged or contaminated threads can change friction and reduce torque accuracy. Threads should be clean and in good condition before assembly.
Skipping the instructions
General torque tables are useful, but application-specific ARP instructions are more important for engine kits.
Confusing torque with clamp load
Torque is the tightening input. Clamp load is the result. The same torque does not always produce the same clamp load.
Not using a calibrated torque wrench
A worn, damaged or uncalibrated torque wrench can produce inaccurate results, even when the correct torque specification is used.
Reusing damaged fasteners
Fasteners with damaged threads, corrosion, visible stretching or other defects should not be reused in critical applications.
ARP Torque Recommendation FAQ
Are these ARP torque values for every ARP fastener?
No. These are general recommendations for bulk fasteners. Application-specific kits may use different torque values, tightening sequences or stretch specifications. Always follow the instructions supplied with the kit.
Are the torque values in ft-lb or Nm?
The torque values in this table are shown in ft-lb. To convert to Newton-metres, multiply the ft-lb value by 1.356.
Can I use engine oil instead of ARP Ultra-Torque?
Do not assume the same torque value applies with a different lubricant. The table is based on ARP Ultra-Torque fastener assembly lubricant. Different lubricants can produce different clamp loads at the same torque.
Why does ARP list clamp load as well as torque?
Clamp load is the force that actually holds the joint together. Torque is the method used to create that preload. Listing both helps show the relationship between fastener size, material strength, torque and resulting clamp load.
Should rod bolts be torqued or measured by stretch?
For many connecting rod bolts, measuring bolt stretch is the preferred method because it more directly confirms fastener preload. Always follow the instructions supplied with the specific ARP rod bolt or rod assembly.
What happens if a fastener is over-torqued?
Over-torquing can stretch a fastener beyond its yield point, permanently damaging it. A yielded fastener may not provide the correct clamp load and should be replaced.
Need Help With ARP Torque Specs?
Performance Fasteners Australia supplies ARP fasteners for street, race, marine and high-performance engine applications. If you are unsure which torque value, lubricant or installation method applies to your ARP fastener kit, contact PFA with the part number and application details.
Contact PFA