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Discussion Starter · #1 · (Edited)
ARP makes the following bolts for our engines:

Main bolts (151-5407)
Crankshaft pulley (251-2501)
Flywheel (251-2802)
Cam sprockets (151-1001)
Head studs (625+ sold by SP63, or the standard ARP2000 151-4301)

All ARP bolts and studs are reusable “indefinitely” provided you never over-tighten them. The steel is stronger than stock, they help hold things together better on built engines. To be honest I don’t know how far the stock hardware can be pushed. Some people use stock bolts all around on built engines, but you must always use new bolts in this case, as the stock ones can be torqued only once. Even if tearing down a brand new block (say to upgrade the rods) you must use brand new Ford bolts.

The ARP bolts and studs all come as kits with an assembly instruction sheet (to be observed scrupulously) and an ample dose of special assembly lube that you must use as directed - except the sprocket bolts which come without lubricant, but you must still use their grease. One bag of supplied ARP grease is enough for the entire engine, so you’ll have plenty.

Clean all stud holes, and blow out any fluid using compressed air - this is crucial, a credible theory for the block cracking problem at the tip of the head bolts suggests that liquid (coolant or oil) might have been trapped in the holes, and highly pressurized when torquing the head, so don’t take any chance.

Lightly oil the “block” side of the studs with a drop or two of your fave assembly oil (I use RedLine Assembly Lube, New Liquid Formula, which is perfect) and install the studs in the block finger tight. The hex socket on the “nut” side of the studs is to help with disassembly in case something is stuck, NOT to torque the studs on assembly.

Lube the thread on the “nut” side, the underneath of the nut facing the washer, and the top of the washer facing the nut, namely the metal-to-metal friction surfaces, using the ARP grease. It is very dark gray and the hardware is black so make sure you spread a light coat evenly and it’s not easy to see.

For bolts, lube the underneath of the head, and the thread.

There is always a ceremony to torque the main and head studs, follow it. In addition, you must undo/redo a few times on new studs depending on the studs: 2x for the regular studs, and a total of 4x with various torque steps for the 625+ superstuds. This is to bed-in the threads, both on the nuts and studs so, when you torque for good, the tension is correct and uniform.

Some people advise NOT to do so on a new MLS gasket for the head studs. If you are tearing down the engine, do the new stud bed-in on the old gasket, as you tear down, and keep the bedded-in nuts and washers with their respective studs. The head will be machined anyway (right?) and you’ll use a new gasket so there is no harm cycling the studs there. I would not use an old MLS gasket on a freshly skimmed head just to prep the studs, for fear of damaging the surface. For a new engine build I was thinking of a sacrificial gasket, perhaps copper or even paper, to do the stud ritual, then remove the head, install the new gasket and torque it only once using the final steps.

Some people have built a bench to be able to torque the studs to spec outside an engine. The preparation of the threads seems important. Some people say stretching the studs (as indicated) is also important.

All hardware must be cleaned prior to installation: the factory anti-rust coating on the studs and bolts must be removed, according to ARP. I use 3M High Power Brake Cleaner and a microfiber cloth for that. Don’t second guess the bolt’s manufacturer.

If your crankshaft is stock (not keyed) the crankshaft pulley and timing gear drive both need new friction washers Ford 1S7Z-6378-AA. You need one washer if you only removed the pulley, or two washers if you also removed the engine cover and removed (or installing) the timing gear/oil pump drive gear.

For the camshafts, you need two new Ford 6M8Z-6278-A friction washers if you removed the sprocket bolts.

These washers are very thin and diamond-coated. They are supposed to be used only once. Since they hold the engine timing together I recommend to do what Ford says and always use new ones: if the timing slips the problems can range from running slightly bad to total engine destruction, so beware.

Edit: I have got a new Ford Fusion 2.0 block and the main bolts that came on it are 12.9 grade high tensile steel. These can be reused. Their rating is 180’000 psi minimum while the ARP main studs are rated “between 200’000 and 220’000” which is better, but there is no real reason to doubt 12.9 steel even if you send it a little too hard, boost-wise. If the head has “12.9” stamped on it, they aren’t single-use “torque to yield” bolts and you can reuse them safely.

The complete kit, with 625+ head studs:
Font Toy Bicycle part Auto part Electric blue

The all-important washers:
Font Material property Packaging and labeling Electric blue Magenta
 

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ARP makes the following bolts for our engines:

Main bolts (151-5407)
Crankshaft pulley (251-2501)
Flywheel (251-2802)
Cam sprockets (151-1001)
Head studs (625+ sold by SP63, or the standard 151-4301)

All ARP bolts and studs are reusable “indefinitely” provided you never over-tighten them. The steel is stronger than stock, they help hold things together better on built engines. To be honest I don’t know how far the stock hardware can be pushed. Some people use stock bolts all around on built engines, but you must always use new bolts in this case, as the stock ones can be torqued only once. Even if tearing down a brand new block (say to upgrade the rods) you must use new Ford bolts.

The ARP bolts and studs all come as kits with an assembly instruction sheet (to be observed scrupulously) and an ample dose of special assembly lube that you must use as directed (except the sprocket bolts which come without lubricant, but you must still use their grease. One bag of supplied ARP grease is enough for the entire engine, so you’ll have plenty.)

Clean all studs holes, blow out any fluid using compressed air - this is crucial, a credible theory for the block cracking problem at the tip of the head bolts suggest that liquid (coolant or oil) might have been trapped in the holes, and highly pressurized when torquing the head, so don’t take any chance.

Lightly oil the “block” side of the studs with a drop or two of your fave assembly oil (I use RedLine Assembly Lube, New Liquid Formula, which is perfect) and install the studs in the block finger tight. The hex socket on the “nut” side of the studs is to help with disassembly in case something is stuck, NOT to torque the studs on assembly.

Lube the thread on the “nut” side, the underneath of the nut facing the washer, and the top of the washer facing the nut, namely the metal-to-metal friction surfaces, using the ARP grease. It is very dark gray and the hardware is black so make sure you spread a light coat evenly and it’s not easy to see.

For bolts, lube the underneath of the head, and the thread.

There is always a ceremony to torque the main and head studs, follow it. In addition, you must undo/redo a few times on new studs depending on the studs: 2x for the regular studs, and a total of 4x with various torque steps for the 625+ superstuds. This is to bed-in the threads, both on the nuts and studs so, when you torque for good, the tension is correct and uniform.

Some people advise NOT to do so on a new MLS gasket for the head studs. If you are tearing down the engine, do the new stud bed-in on the old gasket, as you tear down, and keep the bedded-in nuts and washers with their respective studs. The head will be machined anyway (right?) and you’ll use a new gasket so there is no harm cycling the studs there. I would not use an old MLS gasket on a freshly skimmed head just to prep the studs, for fear of damaging the surface. For a new engine build I was thinking of a sacrificial gasket, perhaps copper or even paper, to do the stud ritual, then remove the head, install the new gasket and torque it only once using the final steps.

Some people have built a bench to be able to torque the studs to spec outside an engine. The preparation of the threads seems important. Some people say stretching the studs (as indicated) is also important.

Studs are all installed finger-tight in the block. All hardware must be cleaned prior to installation: the anti-rust coating on the studs and bolts must be removed, according to ARP. I use 3M High Power Brake Cleaner and a microfiber cloth for that. Don’t second guess the bolt’s manufacturer.

If your crankshaft is stock (not keyed) the crankshaft pulley and timing gear drive both need new friction washers Ford 1S7Z-6378-AA. You need one washer if you only removed the pulley, or two washers if you also removed the engine cover and removed (or installing) the timing gear/oil pump drive gear.

For the camshafts, you need two new Ford 6M8Z-6278-A friction washers if you removed the sprocket bolts.

These washers are very thin and diamond-coated. They are supposed to be used only once. Since they hold the engine timing together I recommend to always use new ones: if the timing slips the problems can range from running slightly bad to total engine destruction, so beware.

The complete kit with 625+ head studs:
View attachment 360239
The all-important washers:
View attachment 360240
I spoke to ARP about this a few years ago and advised them it may help run in their bolts but it wasn't a great idea for the MLS gasket or for that matter the head itself. More the gasket really which is coated with pressure sensitive sealant. No point putting the head through tension and relax cycles either for no good reason. every time you pull the head down it flexes unevenly to a small degree, you cant avoid it. You could tell ARP were more focused on their bolts than someone else's gasket. Personally my suggestion is to make a simple steel block to hold in the vice with a head depth steel bush and simply do the running in process on the bench. That was my plan anyway.

Ciao
 
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