Head Stud Fastener Torque in the Lister Clones

Yikes! Have you ever looked at these Fasteners closely?

I’m not sure how many I’ve looked at but far more than most people I’d imagine. Rajkot makes a pretty crude Nut, last ones I was looking at had threads pulled and a quarter of a thread tore loose and hanging out of the bottom of one of them.  You guessed it, making this nut close to right would take a few more machine steps, and it’s also possible that some who make them don’t know that a simple chamfer could protect the threads from pulling.

My Advice is to look at these head stud nuts closely, if they’re really bad, you’ll Find that there are nuts at the hardware store that match the threads per inch, and the size as closely as the originals do. I chamfer the bottoms, and I use a belt sander to round the edge all the way around the bottom, so the sharp edge doesn’t dig into the head and give a false torque reading.  I sometimes find the bottom side so rough and ugly, I clean it up on the belt sander as well. 

Once I’ve done this, I rub an anti seize into the bottoms, and I coat the head studs with same and wipe off the excess. After I clean up the head surface, and the top of the block, I check the cylinder liner for the proper protrusion above the deck (often .010″)  I place a new head gasket put 30 WT lube oil on the nuts, and incrementally go around with a cresent wrench and get things fairly tight before I grab my torque wrench and set it for 140 Foot pounds. I like to run the machine at full load 2800-3000 watts at sea level until the engine is soaked warm.  Allow the engine to cool over night and retorque to 140 foot pounds again.

If you look at the galling on the bottom of some of the head nuts, it’s easy to believe that whatever the the last guy saw on the torque wrench (if  ever used) was way off.  Breaking those extremely sharp edges is going to make a world of difference. We all hear about leaking head gaskets, I do believe following these steps will eliminate one source of trouble.

George B.      


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2 Responses to Head Stud Fastener Torque in the Lister Clones

  1. bill knighton says:

    Is the reduced torque because the the studs are anti-seized/oiled so that it works out the same?
    What reduced(if my question is a yes) torque do you use on on the rocket bracket nut?

  2. bill knighton says:

    This was a very useful post. I have been having leakage for a couple of years. When I start, at highest compression there’s some gurgling coming out of coolant tank as compressed air makes it’s way in. I have tried dressing the gasket and even tried a really nice gasket from gaskets-to-go that had a bead of silicone around each hole. All leaked. What was happening was that I was doing exactly what was described here. The torque was going into galling the nuts and not squeezing the gasket. Now the torquing was very smooth there is no leak and cranking has a nice spring to it, like when it was new. No bubbling out the coolant hopper either. If I had paid attention and done this all along my head studs wouldn’t look like they were pulled from a ship wreck.

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