One of the most common problems with the small six is blown header gaskets and/or exhaust leaks. However they can be minimized by following proper installation procedures. The use of locking bolts may help, but even then, leaks can and will occur if you don't torque the header flange bolts (or studs) properly. We also prefer studs over bolts, but that's our personal preference. Bolts will work just as well. The use of a high quality gasket is also very important.

torque sequence

Once you have the header on and all the bolts or nuts started, snug them down. Do not over-tighten. Lightly torque the bolts (or nuts) down by starting in the center and work outwards in a circular pattern. Then go back and tighten them down a little more using the same sequence. Make one more pass, only this time torque them down to the final recommended torque specs. Next start the motor and let it warm up to operating temp, then shut it down and let the header cool down completely. Make another pass, again starting in the center, working outwards. Repeat the cycle (warm up, cool down, and re-torque) one more time. The last step, which most people forget or ignore, is to run the engine thru several warm up and cool down cycles, after which you re-torque the bolts or nuts one more time. Again, make sure you start in the center and work outwards. That should do it. However it doesn't hurt to check them a couple times over the next few weeks or months, depending on how much you drive. The important part is running the motor up to operating temp and letting it cool down, several times, before re-torqing.

This photo shows where stock gaskets commonly leak, and eventually blow out.

Related articles: Port Dividers - Headers with A/C - Ceramic Coatings - Exhaust Kits