rocker arm studs too long
Thread Starter
Joined: Oct 2005
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From: Fairfax, Virginia
rocker arm studs too long I received my whole valvetrain from Comp Cams and the 7/16 ARP rocker arm studs they gave me are too long. The threads that thread into the head bottom out on the helicoil tab. I have guide plates so I guess they picked out long ones to make up for the guide plate thickness. I searched around and didn't see anyone else have this problem? I already cut the threads down on two studs, but I would rather buy the right length than have to cut the other 14. If someone could give me the part number to the right ARP 7/16 studs they used WITH GUIDEPLATES I would appreciate it.
That number must be assigned to the studs by Comp Cams. I can't find it under rocker stud listings on the ARP website. For applications with RPM limits up to 7500 and 400# open spring pressures, I've had good luck with ARP #134-7103. There's nothing inherently wrong with cutting the threads down but I suggest that before you cut any more, try mocking up the valve train with the two you've already cut. You need to make sure that the adjuster thread depth on the upper portion of the stud is adequate. Try referring to the diagram found on page 46 of the ARP online catalog. You need to make sure that dimension "D" is appropriate for your assembled valve train. You want to be certain that your rocker pivot is riding on an unthreaded portion of the shank below the threads and that you have adequate threads for the adjuster to engage in order to adjust the valves.
Thread Starter
Joined: Oct 2005
Posts: 1,687
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From: Fairfax, Virginia
Can someone second this. I did consider cutting the tabs off, but I didn't want to nick the threads. Seems to me the tabs would just bend down if I tried to break them off, but I'll give it a try.
On The Tree
Joined: Aug 2006
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They are made to break off they have kind of like a crimp on them so they break off clean. They should have been broken off when they were installed.
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I took a different approach, but one that not everybody can do. If you notice, the OE studs have a bit of a "washer" built into them, in order to help them sit flat on the head. The ARPs do not. I purchased 16 Grade 8 flat washers to put under the ARP studs, so A) it would give the studs a larger surface to sit on; and B) prevent them from running down into the heli-coil tangs, and bunging up the threads.
Here's where I had a bit of a problem...Flat washers aren't a consistent thickness. I was still working at that time, so I brought them into the shop at work and passed them through the surface grinder, equalizing their thickness. I then put them on the ARP studs and torqued them (50 ft/lb, IIRC) into place, and then proceeded with installing the rockers.
If you can find 16 washers of the same thickness, or know someone with access to a surface grinder, that's what I suggest to do.
ran into the same issue also. and the tangs on the factory helicoils don't break off. take my word for it i tried! lol! ended up removing all the stock ones and installing some helicoil brand ones back in, so i could break the tang off. don't reccomend doing this, unless you have alot of patients. was a major PIA!
Thread Starter
Joined: Oct 2005
Posts: 1,687
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From: Fairfax, Virginia
I just finished installing my rocker arm studs. None of the tangs would break off. They would only bend down. I bent them down as much as I could. Did a trial run and saw that it would just start to mess up the first thread when fully torqued. It seemed acceptable so I went ahead and installed the rest. Now I just need my pushrods to finish the valvetrain. Hopefully I'll have this turd done by the end of the year.. we'll see.
