I have owned my car for (94 GT) many,many years. It has had a few different exhaust setups on it,and the one thing they have all had in common. Leaks
I currently have the 4th set of headers ready to install,and am trying to avoid leaks for as long as possible. I’ve used everything from Percy’s gaskets to Copper seal RTV.
My question is-are locking Header bolts the answer I’m looking for?
Back in the old days a trick with the paper style gaskets was to soak them in water for a few minutes before you install them, run the engine up to temp and tighten them down some more, after a few heat cycles you tighten down again. I used the copper looking gaskets and regular header bolts and checked them after a couple thousand miles, all good. At the shop they use that copper stuff from a tube on some applications, seems to work.
I used the stage 8 bolts and still blew out a steel mls gasket. The bolts didn't back out, but, they didn't stay tight. Best thing I've ever done was no gasket, red rtv and tighten them down. Never blew out, never loosened up. It actually makes a cement that has to be smacked to remove the header after pulling bolts. Grover Dill taught me that. He also said "Header gaskets are for the dumbs." I believe him now. He's right.
In the day of my youth I was an aircraft mechanic, so I still do some things that way. The bolt heads were drilled with a #52 drill bit (about .040) using a drill press and lots of WD40 to cool the bit. The head is drilled with the holes in a cross pattern at 90-degree angles to each other.
The bolts are 3/8 -16 thread stainless steel Allen head, 7/8" or 3/4" long depending on the thickness of the header flange that is on your headers.
I bought a 5/16" Bondhus Balldriver Allen wrench, it works like a universal joint. You can tighten up the Allen head bolts at 15-20 degrees off center angle and still get everything tight. Cut the "L" part off the wrench with a cutoff wheel and stuck the straight part in an Allen socket. This works great, because the Allen heads are smaller than even the 12 point bolt heads, and with my fancy tool I can tighten them up with a torque wrench.
Torque the bolts down and pull off about 12" of .032 stainless steel safety wire. Thread the wire through 2 holes, or just one if the other one is blocked by the header pipe. Pull the wire through until the ends are even. Twist up about 2" with your handy-dandy safety wire twister pliers, making sure that the wire pulls the bolt tighter as it routes across the header pipe. Make sure the twist ends at the wire hole in the next bolt, and that it pulls the bolt in the tightening direction. Thread it through and twist up about 3/4"of wire on the other side of the hole and cut it off evenly. Fold it over about midway so that the sharp end doesn't stick you.
The safety wire takes about 10-15 minutes a header pipe to do right and make it look good. The driver's side is easy, but you have to remove the mass air & smog pump air plumbing on the passenger side to have room to work.
i put my first set of headers on my Mach 1 in 1977. Since then, I've had dozens of sets of headers on dozens of engines. In all that time, I've only had a few sets leak. All of that stopped in 1990 when I was told to use RTV instead of any gasket.
There is a process that still has to be followed, and I followed that process this time around to be sure I stop the small leak that showed up this last engine rebuild.
You have to allow the RTV a chance to skin over.
I apply a small bead to the head, or the header and loose assemble the thing. Install the bolts just enough to hold the header in place, but nowhere near tight. Then do the other side the same way. After that side is barely installed, tighten up a set of regular old bolts on the first side until they are freakin mega tight with the longest damn wrench you can get on the bolts.
Then move to the other side and do the same.
Then heat cycle the engine. Check the bolts after the engine cools, tighten as necessary, and you're done.
On the other hand, if you have a warped header, ain't no gasket gonna fix that.
copper rtv for the win, i will never use a gasket again if i can help it. non of them seemed to be worth a damn, I ordered these small 3/8 head bolts from kooks?? they came with special washers. Easiest header install i have had yet, using the same skin over method mentioned above...
I Just use the ARP 12-point header bolts. With Iron E7's I just torqued them down really well and never had an issue with any of them backing out. Of course with AL heads, I would be afraid to crank them down as much as I did on the iron heads