SC Head stud hole problem

Wil · 06-21-2006, 05:24 AM

I had a dilvar head stud broken at block level. I took it to an EDM shop to have it removed. After they removed the stud, the guy ran a 10MM 1.5 tap through the threads. I threaded in a new head stud and it seems rather loose and a bit wobbly. The guy said there would be plenty of strength for 50 ft. lbs since the threads were deep enough. If I use red loctite, do you think that the threads will hold? or now do I have to put in timeserts.

Arent Timeserts also threaded to 10MM 1.5 ? In this case what is the difference?

herman maire · 06-21-2006, 05:35 AM

I really dont think that it should be loose at all.

Thats all I can contribute .

euro911sc · euro911sc's Garage

I had a question very similar to this that should provide you with some of the answers you need. See this thread:

What Tap to Clean Head Stud Holes?

Basically, the tap your machinist used was probably a cutting vs. cleaning tap and opened it up a little. I did a similar thing on my case. One out of 24 is probably ok, though this is the 1st engine rebuild for me.

Best regards,

Michael

lindemans · 10:26 AM

Given the efforts it would require to (again) open up the thing later on, I would never assume it will hold.

The Torque down value may be not that much, but why do you think these things would snap in the first place !?
These rods get the full force of the combustion process up their...eh...threads !!! You bet that will substantially exceed the static torque value.....
Such remark from a mechanic really surprises me....

DON´T take any chances here, I would have an insert or helicoil mounted here by someone who does it right the first time. There is no room for continuous error here.....

These high strength parts do not belong in a wobbly thread/hole, no way. I would go to the mechanic and have it fixed properly.

john walker's workshop · 06-21-2006, 10:29 AM

one case saver install won't kill you. just make sure it's dead straight. the edge is close to the spigot edge so be real careful or you will get an oil leak.

schloss · 06-21-2006, 12:50 PM

does anyone know of or heard of a self threading 'sleeve nut' that will go over a broken head stud? Of course this would only work if the stud broke high enough for it to catch. or a sleeve type nut that could catch the bottom threads closest to the case? I just was wonderin, since it could be a low budget solution.

Jim Williams · 06-21-2006, 06:10 PM

I have learned something about taps over the last several years. euro911sc mentions this. All taps are not created equal, and when you buy one, you can't count on the package to say what type of tap it is, or to what tolerances it was built. I have a brand new Hanson brand tap (10 x 1.5 mm) I bought at an Ace hardware to use as a chasing tap, and measured it on a hunch before using it. It measured in excess of what the diameter for a cutting tap should measure. Had I used it to chase the head stud holes in my case, there would have been some really loose fitting studs. I would do as John suggested and get someone who could be trusted to put in a case saver or time-sert, and get it installed straight. The cylinders are hard enough sometimes to maneuver on over the pistons when the studs are straight. If one or two studs are not straight, the frustration level goes up significantly.

Just my $0.02,