Always impressed by the complexities of various jobs on our cars. Never imagined choosing and installing head studs would involve decision trees, but apparently it does.
Quick and dirty, I'm leaning toward ARP studs because I can find them for the same $200 the OEM ones are on 944online and would follow the installation instructions that come with them. Also purchased a thread chaser to clean out the block threads as it sounds like stud removal can be pretty rough on the aluminum.
I have seen people questioning the high torque value off 100 foot pounds and saying they've gone lighter.
What has experience shown you all?
Head stud selection and installation dance
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Tom
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I went through many many head gaskets on my 3 L motor early on. Raceware insisted that 65 ft lbs was the perfect amount, but it just wasn't and I finally settled on 95-100ft lbs. If you use ARP or Raceware, I'd just go to 95, at least with a stock or wide fire gasket. If you have a more modern exotic gasket, my experience may or may not apply... @michaelmount123 should have valuable insights on this...
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michaelmount123
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This is from one of my old posts with new edits:
The factory uses a strong thread locking compound when installing the studs, making them very difficult to remove. I use a Snap-On stud remover (M12x1.5) and a powerful impact wrench which is the best tool for the job. Occasionally heat is required on the block at the base of the stud area for those studs being difficult. I'll note here that LocTite should NOT be used to re-install the new studs. Consulting the LocTite instructions will tell you why. Instead, I install studs in the block with CMD Extreme Pressure Lube #3. It's thick, holds the studs from turning, and makes it easy to remove next time around. Amazon has it.
Occasionally Porsche used M12x1.75 threads in the block. I don't think this was a change, but probably something done when normal stud supplies were low. I always compare the block side threads on the old stud with the threads on the new stud to make sure I've got the same threads. This only applies to the block side threads.
Chasing the block threads is necessary, but a tap is the wrong tool. Taps will remove additional metal and weaken the threaded joint. (Yes, not supposed to happen, but what is all that cut aluminum that comes out with the tap?) I use an old head stud with 2 or 3 axial grooves cut into the block side threads with a thin cut-off wheel. A nut welded on the opposite end mades it easy to run in and out of each hole and clean the threads without removing additional metal. After chasing 10 stud holes you'll be glad you took the time to fab one up. A 3/8" electric impact makes it quick work. Blowing out with compressed air completes the process and the new stud will go in easily. Use the CMD #3 and set to the specified height (RTFM).
Each non-Porsche stud manufacturer specifies a specific lube for the nuts and the top of washers, whereas the FSM specifies engine oil for the stock studs. Adhere to these specs. I use the Porsche head washers even with the ARP studs and nuts. Their thickness and larger diameter spreads the load better than what ARP supplies.
ARP now specifies 100 ft. lbs. torque for their studs. They understand clamping force, so respect their spec. That said, (like Tom) I get nervous when going beyond 95. Use the factory sequence and multiple steps. With stock head studs and their lower torque, I've had occasions with MLS head gaskets (Cometic) where the center studs were loose after completing the torque sequence. This was due to the stamped embossing on the head gasket resisting the torque. After completing the torque sequence, I now go back to each individual stud (in sequence), back it off completely, and re-torque to the final setting with a single pull. Do this with each nut individually.
MM
The factory uses a strong thread locking compound when installing the studs, making them very difficult to remove. I use a Snap-On stud remover (M12x1.5) and a powerful impact wrench which is the best tool for the job. Occasionally heat is required on the block at the base of the stud area for those studs being difficult. I'll note here that LocTite should NOT be used to re-install the new studs. Consulting the LocTite instructions will tell you why. Instead, I install studs in the block with CMD Extreme Pressure Lube #3. It's thick, holds the studs from turning, and makes it easy to remove next time around. Amazon has it.
Occasionally Porsche used M12x1.75 threads in the block. I don't think this was a change, but probably something done when normal stud supplies were low. I always compare the block side threads on the old stud with the threads on the new stud to make sure I've got the same threads. This only applies to the block side threads.
Chasing the block threads is necessary, but a tap is the wrong tool. Taps will remove additional metal and weaken the threaded joint. (Yes, not supposed to happen, but what is all that cut aluminum that comes out with the tap?) I use an old head stud with 2 or 3 axial grooves cut into the block side threads with a thin cut-off wheel. A nut welded on the opposite end mades it easy to run in and out of each hole and clean the threads without removing additional metal. After chasing 10 stud holes you'll be glad you took the time to fab one up. A 3/8" electric impact makes it quick work. Blowing out with compressed air completes the process and the new stud will go in easily. Use the CMD #3 and set to the specified height (RTFM).
Each non-Porsche stud manufacturer specifies a specific lube for the nuts and the top of washers, whereas the FSM specifies engine oil for the stock studs. Adhere to these specs. I use the Porsche head washers even with the ARP studs and nuts. Their thickness and larger diameter spreads the load better than what ARP supplies.
ARP now specifies 100 ft. lbs. torque for their studs. They understand clamping force, so respect their spec. That said, (like Tom) I get nervous when going beyond 95. Use the factory sequence and multiple steps. With stock head studs and their lower torque, I've had occasions with MLS head gaskets (Cometic) where the center studs were loose after completing the torque sequence. This was due to the stamped embossing on the head gasket resisting the torque. After completing the torque sequence, I now go back to each individual stud (in sequence), back it off completely, and re-torque to the final setting with a single pull. Do this with each nut individually.
MM
I did the same with my ARP studs and SCE gasket. I used the M44 larger washers that take the whole space in the head.
I would add, mark the studs with paint line so you can keep track of rotation. Also set them all the same height. You don’t want to bottom them out. If you don’t have a welder you can double nut on the stud to lock them in place to chase threads. And you can scuff the washers on the bottom to help them grip and not rotate with the lube on top between the nut as mentioned.
I would add, mark the studs with paint line so you can keep track of rotation. Also set them all the same height. You don’t want to bottom them out. If you don’t have a welder you can double nut on the stud to lock them in place to chase threads. And you can scuff the washers on the bottom to help them grip and not rotate with the lube on top between the nut as mentioned.
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michaelmount123
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Why not use Loctite when installing head (or lower case half) studs? Anyone?
Thanks all for the tips!
I'll go with the ARP head studs and it seems like 95 would be fine. I'll be going with a stock head gasket with a newly sleeved bottom end.
Between the double nut method and a stud puller with a toothed wheel from amazon I got 9 of the studs out, but there's one I'm going to save for the machine shop as heat and penetrant and the other methods I have only seem to damage the stud without moving it at all.
I'll try the method of using an old head stud with a welded nut as a thread cleaner. I got the thread chaser but it's maybe 6 inches long and I'd have to weld it to something anyways to chase the threads.
I'll go with the ARP head studs and it seems like 95 would be fine. I'll be going with a stock head gasket with a newly sleeved bottom end.
Between the double nut method and a stud puller with a toothed wheel from amazon I got 9 of the studs out, but there's one I'm going to save for the machine shop as heat and penetrant and the other methods I have only seem to damage the stud without moving it at all.
I'll try the method of using an old head stud with a welded nut as a thread cleaner. I got the thread chaser but it's maybe 6 inches long and I'd have to weld it to something anyways to chase the threads.