ORIGINAL: MTK
I use Permatex Ultra Copper hi heat gasket sealant. A thin layer on the flange and in the holes. I have also used NordLoc washers under the bolts and that combination is solid. I've heard others use red Loctite but I have not.....Ultra Copper is the best material I've used so far and it seals and locks everything long term. Lost header bolts just don't happen anymore.....
I am really hoping that Hobby services comes through for me this week....
+1
Ultra Copper and no locktite, Nordlocks are great. Lubricate the threads to achieve proper torque on bolts.
If you can't find Nordlocks in small quantities, Micro fasteners sells Dyna-Locks ranging from M3- M6 and appear to be Nordlocks. Expensive at over $5.00 for 10 pair but still well worth the price. Install your muffler or header and it will not come loose until you remove it.