Re: Cam Cap Stud Problems
Posted: Tue Jul 16, 2019 5:14 am
I've done some more investigation regarding this using the Lock N Stitch option and here are a couple of possibilities:
From Helicoil charts I have determined that the major tapping diameter for the 5/16" Helicoil insert that has pulled out is 0.3884" (9.87mm). This means that you will need to choose a new insert that has a minor tapping diameter 9.87mm or greater for installation.
Best quality option:
The best option is to use a Full Torque FPS solid plug that is 0.465" diameter and 0.575" in length. The solid plug can be drilled and tapped for the 5/16" stud thread and it can also be bored for the cam cap dowel location. The resulting repair will be perfect, better and stronger than original. The kit part number is FPS30400K.
2nd option:
Use a Full Torque FFT style insert. The extermal diameter is the same as the FPS plug above however it is fully threaded in the middle with a 5/16" thread. You can't really bore it for the cam dowel location. You may hovever be able to cut the dowel down so it doesn't protrude above the cam cap surface. The location accuracy will therefore depend on th fit between the shoulder of the stud and dowel inside the cap. Not ideal but may prove to be sufficient if the dowel location on the other side of the cap is still in good condition. The kit part number is FFT3S51618K
In my opinion the Lock N Stitch method of thread repair is second to none (no affiliation). I'd recommend however that the inserts be inserted by a professional with access to milling equipment, etc. to ensure proper machining accuracy. Refer attachments below.
Welding to fill the hole and re-tapping was not recommended in my case because of the depth of the hole, possible distortion, and due to lack of appropriate heat treatment the weld material would be soft resulting in new threads stripping easily.
From Helicoil charts I have determined that the major tapping diameter for the 5/16" Helicoil insert that has pulled out is 0.3884" (9.87mm). This means that you will need to choose a new insert that has a minor tapping diameter 9.87mm or greater for installation.
Best quality option:
The best option is to use a Full Torque FPS solid plug that is 0.465" diameter and 0.575" in length. The solid plug can be drilled and tapped for the 5/16" stud thread and it can also be bored for the cam cap dowel location. The resulting repair will be perfect, better and stronger than original. The kit part number is FPS30400K.
2nd option:
Use a Full Torque FFT style insert. The extermal diameter is the same as the FPS plug above however it is fully threaded in the middle with a 5/16" thread. You can't really bore it for the cam dowel location. You may hovever be able to cut the dowel down so it doesn't protrude above the cam cap surface. The location accuracy will therefore depend on th fit between the shoulder of the stud and dowel inside the cap. Not ideal but may prove to be sufficient if the dowel location on the other side of the cap is still in good condition. The kit part number is FFT3S51618K
In my opinion the Lock N Stitch method of thread repair is second to none (no affiliation). I'd recommend however that the inserts be inserted by a professional with access to milling equipment, etc. to ensure proper machining accuracy. Refer attachments below.
Welding to fill the hole and re-tapping was not recommended in my case because of the depth of the hole, possible distortion, and due to lack of appropriate heat treatment the weld material would be soft resulting in new threads stripping easily.