Stud question

[Don Coatney]

Thanks to Charley (olddaddy) Akers I now have a full set of NOS head studs that I will use when I install my SPITFIRE head. I also have in my inventory the required grade 8 nuts. I also have in my inventory enough grade 8 lock washers as pictured. My question is should I use the lock washers or should I buy some grade 8 flat washers and not use the lock washers.

[Plymouthy Adams]

Don..if it were me, would not use the lock washer..it tends to cut into both the head metal and the nut itself. Instead i would go to the local Mopar shop and get the special flat washers that are use on the 2.5 engine and I think the 3.0 uses them also...these are superior grade wahsers...look at their design..think you will approve.

[Don Coatney]

Tim;

Are they the correct size or are they metric?

[martybose]

I agree about not using the lock washers. As for the washers, you could always buy the hardened and ground washers that ARP sells for their head stud kits; they will sell you anything you want individually, including the taller nuts they use.

Jus don't forget that with the fine threads on the studs you need to reduce the torque spec. If memory serves, something like 55 lbs is about right.

Marty

[Don Coatney]

Tim;

Thanks for the phone call. Is this what you are talking about? McMaster Carr has these but they are $2.08 each.

The phone was silent when I told you my friend Don Coatney gave me the grade 8 nuts and lock washers. Here is a picture of me and my friend Don Coatney. He sells hardware for Lawson Products. He is the National Military accounts manager for them and retired from the army. He lives about 15 miles from me and we have never made a family connection. Not only are we close to the same age and shaped sort of the same but our signatures are almost identical.

[Plymouthy Adams]

In reality..the torque applied is the felt the same on the head regardless of the fine thread, coarse thread or be it grade 5 or grade 8..the fine thread will be able to substain a bit more torque than the coarse. (more thread but slighly shallow) The grade of the bolt will be in the tensile strength...which will yield a higher torque value. Now in regard to statement that fine thread be x-pounds less...in reality, the statement is between dry torque or lubed torque whereas the indicated torque will be less when run up lubricated...

[Plymouthy Adams]

Shazzam Don..that be the ticket..these babies will lock with out damage to the surface of the not or the head...

[grey beard]

Then why do Mack, Cummins and Cat all show different torque values for USS and SAE threads, if they're all the same? Methinks thread pitch does make a difference in torque requirements, as well as the wet/dry factor mentioned above. If you really want a shock, check out what teflon tape does to the torque values of a fastener.

Don, as to your original question, my feeling is that head boltsand nuts do not neet lock or flat washers. It is the application that usually dictates this need, not the fastener. On any reciprocating mass - like a flywheel - there had better be good qualirty lock washers. Original flathead motors used no washers under the head bolts. Now if you were installing an aluminum head, I'd certainly agree that a flat washer would be required - just common sense. JMHO

[Plymouthy Adams]

read my earlier post closer as I stated just what you did.....I addressed coarse and fine and grade of bolt...I stated that SAE NC and SAE NF of same diameter the NF will indeed can take a higer amount of torque based on the more threads per inch and aslo the grade of the bolt is the main consideration for higher torque application....

[Don Coatney]

Dave;

One possible difference requiring a washer is the fastener head size. A standard 7/16" bolt has a 5/8" head. The head bolts supplied from the factory have a 11/16" head. In my case the nuts I have are 11/16". However I want to use washers as it will make a neater looking instillation. I believe the earlier model Plymouth engines all used studs. I am not sure if they used washers but hopefully someone in the know (Tod Fitch) will chime in.

On the torque values I agree with you and Marty. Fine threads require a lower torque. And as was mentioned a bit of lubrication on the threads will throw off any torque reading.

[TodFitch]

In reality..the torque applied is the felt the same on the head regardless of the fine thread, coarse thread or be it grade 5 or grade 8..the fine thread will be able to sustain a bit more torque than the coarse. (more thread but slightly shallow) The grade of the bolt will be in the tensile strength...which will yield a higher torque value. Now in regard to statement that fine thread be x-pounds less...in reality, the statement is between dry torque or lubed torque whereas the indicated torque will be less when run up lubricated...

A threaded nut/bolt converts the torque applied into tension on the fastener. Basically the threads act as a continuous inclined plane. If you look at the force vectors, you will see that for the same torque value the finer threads will give you more tension on the fastener. Since you are actually after a specific tension on the fasteners you need less torque with fine threads to get to the same clamping force.

Lubrication does make a difference since friction in the threads will result in more force being wasted in over coming the friction. And also because the friction will result in a rotational load on the fastener which is undesirable.