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Torque Specs and problems with torquing - head bolts, rod bolts

Help required :

I am putting the engine together. And am having torquing problems.

The head studs are new, but tightened the head bolts over 50 lbs pulls the studs out of the block. Machinist has heli-coiled problem studs to date (2) but is worried about others.
I was living under Lance Haynes directives of torque to 50 lbs, leave overnite and re-torque to 70 lbs. Get it warm to 180 degrees then re-torque to 70 lbs.

WHAT SHOULD I DO, I feel like going with what I have and if problems occur will pull head and heli-coil all stud holes next winter. ???

What should the torque be on the piston rods ? Machinist is scared of going above 35 lbs. and he has torque them to 35 lbs. and them wired so they will not loosen ...


You can see my dilemna; I thank all HELP sent.

Where Are You From? Peace River AB Canada

Do You own a car built by Durant? 1926 Model M Touring

Re: Torque Specs and problems with torquing - head bolts, rod bolts

First, make sure the torque wrench reads correctly.

Are you putting the correct end of the stud into the block? There may be a difference in fit. A rational design would have the nut strip before the block does.

In industry, there are "GO" and "NO-GO" thread gages to check if your internal threads are too big.

The minimum pitch diameter threaded hole is the basic size, and could be larger, depending on the precision class. [Class 1B, 2B, 3B] The studs also could vary in thread specs from Class 1A to Class 3A fit,(close fitting)or even interference fit, Class 5B. That said, in the old days, they believed in tight fits.

Today, a hand tightened fit is okay. Now they use Locktite pipe sealant with Teflon, to keep the water from leaking past the threads. It also does a little to hold the stud, so you can unbolt the head without the studs coming out.

It seems to me that you should be using studs with the biggest pitch diameter for a theoretical Class 5 fit. With the wear you have, it probably can't get there, but it might come out equivalent to a Class 2 or 3.

I've heard of the threads being eaten away by some chemical dips used for cleaning and derusting. If that's happened, you will need inserts.

Do You own a car built by Durant? yes


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