Torquing bolts/studs

[Bud Tierney]

A recent inquiry for pre-war torque specs reminded me of an old question. My experience was all from the pre-torque wrench days---we just snugged 'em down, warmed 'em up good , snugged 'em a little more and watched for leaks, trying again after running for a few days, always keeping in mind we seldom replaced any nuts, bolts, or studs. that everything was old....

So==what's the "understood" conditions for the torque settings in the various bearing catalogs...just as the nuts/studs/bolts came off/out??---nut threads eyeballed, studs hit with a wire brush, bolt block threads "cleaned", blown out?---all really, carefully cleaned?---not all bearing catalogs list torque; in those that do I find no such info/recommendation...

We did try to remember to look for pulled or poor threads when something'd blown a head or manifold gasket (try being the controlling element here)...this was all shade-tree work......

I've always assumed oiling and/or new nuts/studs/bolts  also affected torque optimums...

[Dave Mellor NJ]

They used to tell me,"Tight as you can get it and then another 1/4 turn".

[Bloo]

I always heard "tighten it until it strips, then just a little bit less".

 

But seriously, torque specs are almost always for cleaned/chased oiled threads. If not, the book will specify, for instance bolts into a water jacket will have sealer on the threads instead of oil.

 

If the threads were not clean and oiled, you could not know whether two of them would behave the same.

 

There were tables in older books of torque specifications just based on the size and thread pitch of the bolt. I''ll bet thats in Dykes, for instance, but I can't remember for sure where I saw it. I suppose that would be the only resource for someone using a torque wrench before car manufacturers started publishing specs.

 

14 hours ago, Bud Tierney said:

My experience was all from the pre-torque wrench days---we just snugged 'em down, warmed 'em up good , snugged 'em a little more and watched for leaks, trying again after running for a few days, always keeping in mind we seldom replaced any nuts, bolts, or studs. that everything was old....

 

Thats pretty much how it was done as far as I know.

 

Sometimes you can look up a newer engine of the same engine family, and get the spec that way, if the bolts have remained the same size and pitch. If enough years have passed between what you are working on and what you got the spec from, it might pay to do a little less, as the earlier metallurgy may be not nearly as good.

[Spinneyhill]

Just ask the www. You will find lots of charts. Use the grade 2 bolt value for size and thread count per inch of your bolt.

[Owen_Dyneto]

You might be guided by data in this chart.

[West Peterson]

Head bolts to block on an inline flathead: start from the center and move out alternatively to the front and back. 40 pounds to start, then do the process again at 60 pounds. Drive the car, get it warmed up, let it cool slightly, and check/re-torque at 60 pounds. Do this check/re-torque a couple more times during the first 250-500 miles.