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I’m trying to start the 327 in my 1957 NAPCO conversion project. I’m installing a temporary exhaust set up in order to break in the cam. I have aftermarket Rams horn exhaust manifolds with down pipes that are flared for the donut type seals. I’m searching for a torque value for the stud nuts that hold the assembly together. The studs are 3/8-16” into the flange and 3/8-24 on the long end. Any help would be very appreciated. I’m getting a little bleary eyed with all of the last minute gotchas!
Thank you,
Larry

Torquing a flange against a donut gasket is a colossal waste of time, since the donut compresses as the nuts are tightened. "Snug" plus about 1/4 to 1/2 turn is plenty, and follow up with another tighterning after some run-in time. Some jobs just require some common sense- - - -there's not a specification for everything.
Jerry

Jerry,with all due respect, I simply asked for some help. I don’t believe my desire to do the correct thing when putting my truck together is a “colossal waste of time.” Sometimes it might be more constructive to answer the question rather than telling the questioner how stupid he is. BTW…I’m 74 years old and other than two years of high school auto shop, and many years of doing my own auto maintenance, I am a complete novice. I do appreciate people like you who offer advice, but I don’t think those of us who aren’t experts should have to feel as though we’re somehow a lesser version of yourselves.

Sincerely,
Larry Jones

LAJones48,

Larry, he meant, torquing a flange was a waste of time, not your ‘doing the right thing’ to learn about trucks!

Ed

Do an internet search for bolt torque values or fastener torque values. Each bolt manufacturer will have slightly different values, but the numbers are pretty close to each other. They will specify size, grade, thread count and things like dry, oiled, etc. When an OEM auto manufacturer doesn't specify a torque value, refer back to a bolt manufacturers torque value. For the studs, you would probably be safe to assume they are not grade 8's and could use the grade 5 torque numbers.


Google search for fastener torque value.

I would be leery of using published torque specs on old cast iron especially since studs have a blank area between the fine and course threads. When the course threads bottom out the blank area can crack the flange where it is thin. Tight plus a 1/4 turn sounds good and you can do a "practice" run to see if backing the fine thread nut off also removes stud.

Thank you for the suggestions

Sorry about sharing 65 years' worth of practical experience. Trying to apply a specific amount of torque to a surface that's capable of compressing is going to be a frustrating experience that will eventually lead to stripping threads or breaking off bolts, but some people insist on peeing on the electric fence for their own enlightenment instead of listening to the advice of those who have "been there- - - -done that!"
Jerry

Again, with all due respect, what I’m trying to convey is my question is simply an honest question. If the answer is that there is no specific answer, I can live with that. Perhaps we might agree that your use of the term common sense might refer to many years of real world experience. As a devoted hobbiest, I’ll never accumulate the level of experience that those of you who have made your careers in automotive science. My form of common sense in this area is to ask the question if I’m not sure. I guess the price to pay for an answer is a little dose of “What in the ___ is wrong with you?” So be it.
Larry

LAJones48 If you use the long brass nuts on your exhaust they will start squeaking when you get close on tightening.Those donuts are kind of a turkey shoot,if its not leaky better stop. Some even had springs in there you know when the engine torques something needs to give a little.

Thank you. This is why once I do the initial break in run, I’m taking my truck to a local exhaust wizard to have him fabricate the final exhaust system.