SSI's onto a '76S step 3

Jim Sims · 03-14-2004, 05:47 PM

Did a lot of cleaning plus refurbishing of the heater valves. Also learned a bit of useful information about putting on the passenger side engine sheet metal piece - get the screw that is under the cam tower oil line fitting started and in about half way before the installing the other screws.

Now putting parts back together:

Here is all the new hardware, new heater hoses and the special bent 12mm wrench which comes with the SSI's. In my selection I have one too many barrel nuts (only need five) and I'll need another copper plated flanged prevailing torque hex nut (need seven). The hardware less the wrench and the hoses weighs 1.2 lbs and the two new heater hoses together weigh 0.5 lb.

Close up of plugs; 10 x 1 plugs with 10x14 copper seal rings for the air injector holes and a 26 x 1.5 plug for the muffler EGR port fitting. The 26 x 1.5 plug was made from Metric and Multistandard Components Corp. socket pipe plug (item 908) by machining a .258" deep countersink (top diameter .830" x .555" bottom diameter).

I had some concern about the using the new copper plated flanged prevailing torque hex nuts on the existing studs coated with anti-seize compound. Following advice to reduce the tightening torque to 15 ft-lbs, I then made a test rig out of the one stud that came loose and tested the stud and nut together. Better to break a stud on the bench than in a head. I "double nutted" the head end of the stud and mounted it in a vise; then I slipped a socket over the stud (for the nut to have something to clamp against), added a couple of washers, buttered up the nut end threads with Permatex Anti-Seize (133A) and screwed on the the nut. The nut was tightened to 15 ft-lbs without problem.

More further down in thread. Jim

Jim Sims · 03-14-2004, 05:54 PM

Missing plug image.

Jim Sims · 03-14-2004, 06:03 PM

New SSI's; note that there are only five access holes for barrel type nuts.

Installed the one stud that had backed out using double nut technique and red Loctite. The threads in the head were previously chased to remove any debris or old thread locking compound. Also put anti-seize on the air injection plugs and installed them.

Finally the the muffler EGR port plug is installed.

Next time (step 4) the SSI's go on.

Cheers, Jim Sims

Jim Sims · 07:11 PM

Having trouble with images tonight.

SSI's for a 911 1976S. They each weigh 14.5 lbs.

Schrup · Schrup's Garage

Nice write up Jim, I will be doing this in a few weeks to my SC. I have to get it back together, then pass my final smog, then I can install them. Would you recommend using antisieze & only 15lbs of torque on my thin flange SSIs as well? I plan to use the Island Dremel method to get my nuts off, although I have already started to soak them in Aero Kroil & I think some of them may have budge the other night. But I'm afraid, very afraid. I seem to be able to get to them all using a offset double boxend wrench. I'll probable order the hex socket from Wayne. I already have my oil lines, I just need the hardware & gaskets. I plan to do my first valve adjustment while I have the exchangers off, had you considered this?

Jim Sims · 03-14-2004, 07:29 PM

Torque required for a stud is based on stud size, stud material strength, and thread lubricant. It is also influenced by the the prevailing torque feature (last bit of thread is distorted) of the nut The thickness of the SSI flanges shouldn't matter. I reduced the torque to 15 ft-lbs on account of the anti-seize lubricant used on the threads; if I have a leak I will retighten. I would suggest you use a torque wrench when you attempt to remove the nuts on your exhaust system. Set it to 15 ft-lbs and if a nut doesn't move at that torque level get an oxy-acetylene torch and heat the nut to a red color, then remove the nut while hot. I adjusted my valves when I had the engine out. I almost think it is easier to drop the engine than fight the poor access; especially on the passenger side. Cheers, Jim

Randy Webb · 08-20-2004, 10:44 PM

Two addenda:

The reason JS reduced the torque (I think) is that the anti-siez makes the friction on the threads less (more slippery). This affects the tension on the stud. This applies to Loctite (except the wick-in green style that is applied afterwards), oil, assy lube, etc. Tension usually causes stud failure right where the things are necked down (if they are).

If your torque wrench goes from 10 (or 15) ft-lbs to 90 or something, it will be maximally inaccurate at the extreme. So buy a decent one with a lower range.... or educate your wrist.