I have put headers on a couple of 67 390 cars, it dont get much tighter than that, one thing that works for me is to use allen head bolts, helps with clearance problems.

 

How in the world do you fit a clicking torque wrench to an Allen head bolt?

 

easy, allen head sockets, handy little suckers, always used a lot of allen bolts on race engines, and truck engines

 

Never used a torque wrench to put headers on before.

 

Yeah I agree, I have always torqued headers by feel. Check the spec, tighten by feel, if it leaks tighten a little more but don't overdo it.

Hey, paladin_1888, that idea of using allen heads is a gem! I will keep that in mind next time I install some headers on anything. For grins I checked on my car and I could have probably used them everywhere except for one bolt. The 6th one back from the front on the driver's side was the royal pain. That is the bolt behind the third tube, for the particular header I used, that tube curves up and then back down. It curves right over the bolt hole, not sure you could get an allen wrench in there. Getting them started would still be a pain but most could have been tightened a lot easier using allens.

Really on my car the shape of the tubes was what created difficulties, not space in the engine bay. The 71-73 cars were built to accomodate the 429 / 460 engine so a fairly roomy engine bay.