I don't know the "official" method but I did the sequence in two steps. I don't have the info in front of me because I sold the car and sent the manual with it. I think the spec was 80 lb/ft. I would torque to about 60 then start over and go to 80 in the same sequence. I'm not sure what you mean by 'loosen then tighten'. They would be loose if you had the head off. My reference is on a 38 216.

Hi Mike

Like Tiny, I don't know what you are referring to when you talk about loosening and then tightening.

At NO point during the process of torquing a head are bolts "loosened".

Torque in stages as Tiny recommends.

Some may disagree but, I never put a bolt in without at least a little oil on the threads.

Without oil, the amount of torque required just to overcome the friction in the threads can vary wildly between bolts, so the actual residual torque applying the desired stretch/preload to the bolt can vary wildly as well.

As you approach the final torque value, turn the bolt "slowly but surely" with no stoppages until the torque value is reached.

After all bolts are up to their final torque, I always go through the entire torquing pattern again using a torque just a few pounds higher.

Due to "static friction", the bolts seldom move on that final check, but it catches any that may not be quite there for some reason or another.

Hope that helps.  🙂

Here is a link to an interesting discussion in the old forum about head bolts and torquing them down: https://vccachat.org/ubbthreads.php/topics/353976/1934-master-with-rebuilt-engine-retorque-head.html

Hope this helps. Dean

Thanks for the reference Dean, I should have been more specific on the retorquing that I was referring to.  Gene's advice is what I was referring to, after a bit of usage the head bolts need to be retorqued in the same pattern from center out while the engine is hot.  He didn't address my question about the specific process to follow in the retorquing and now I am thinking that maybe I've been doing it altogether incorrectly, so now I'll change the question.  During the retorquing, I have always loosened each bolt slightly (maybe a quarter turn) and then retightened to ensure an accurate reading.  Is the proper process just to put the torque wrench on and go straight to tightening, if the torque wrench clicks, move on to the next bolt?  In other words, I would only be tightening bolts that were then not quite up to the right torque?

@mike-reinecke 

Short answer is yes, you should be only tightening as you go through the torquing (and hot re-torquing) sequence.

It sounds like you are concerned with the issue of overcoming the static friction in the threads when torquing up to the next higher torque setting.

That is an issue... and can be better addressed by making sure there is a large enough difference between the last torque setting and the next torque setting.

For example... don't increase by something like just 5 ft/lbs at a time.

Go up by at least 10 or 20 ft/lbs at a time.

Especially with the last round.

So for example, if you are planning on torquing to 80 ft/lbs as per Tiny's post above, torque to 60 on the second last torquing, then up 20 ft/lbs to 80 for the last go round.

Then, without any loosening, just recheck hot to that same 80 ft/lbs... or maybe 82 🙂.

PS

The earliest torque value I find from Chevrolet is in the 1941 shop manual (as I believe Gene pointed out) and that value is 75- 80 ft/lbs.