A bad day in the shop

So today was to be a great day. But as happens more than I like, Mr. Murphy had other ideas. I was torquing the head down going at 30 lb steps. When I got to the 92 lb portion of the program, there were two center studs that just wouldn’t get to 92. They would torque to 83 lbs but kept turning. I couldn’t get them to torque to 92 lbs. on the third round of retightening, one stud in question broke! Of course it’s late afternoon on a Friday so I can’t even get anyone to answer the phone about replacements. Add to that, when I removed the head, the head gasket got buggered, so now I need a new one of those also.
Does any one know of a source for the center head studs and another head gasket? I sent an email to Worcester but they’ve all gone home for the weekend and they don’t list 2.5L studs on their site.
On the good news side, the engine is back in the car. The Volvo Tranny with overdrive is properly attached, new rear engine Mount fabricated and bolted in and I’ve just about finished the modification to the propeller shaft.
Two steps foreword, one step back!


Not all the studs use 92 ft-lbs torque. There are four studs that have slimmer centre sections (waisted studs) that only take 62 ft-lbs.


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Crap! I didn’t see that. Guess I was moving too fast! That was an expensive miss read!

Hi Wayne, good to hear of your progress and sad to hear of the setback.

The 2 1/2 litre engine has three specifications of studs fixing the cylinder head.
C.630 Stud, fixing Cylinder Head, Plate No. A.10, no. per Unit 9
C.1633 Stud, fixing Cylinder Head, Plate No. A.11, no. per Unit 4
C.631 Stud, fixing Cylinder Head, Plate No. A.12, no. per Unit 6

The C.1633 are waisted studs located as shown on Plate B.31 from Peter, these call for torque of 750 lbs. ins = 62.5 lbs. feet.
The C.630 and C.631 call for torque 1,100 lbs. ins. = 92 lbs. feet.

N.B. Torque application benefits from known calibrated torque wrench and thread lubricant considered.

The last head studs I bought were provided via a supplier to Worcester Classic Spares. You might also try Alan Gibbins (The SS Register - Jaguar Drivers' Club Register , or Brian Gibbins)

And if twisting on the head stud occurred, you may give some thought to thread condition in the block. If lucky you just got plastic stretch in the head stud or the head stud threads up top gave out in the acorns. Also, make sure the acorns have adequate internal thread not to bottom out inside the acorn (there are reproductions which do not have necessary clearance).


Thank you both for your clarification. I’m still looking for a replacement “waisted” stud and a head gasket for a 2.5L. Any body have a spare stud?

When some of studs on my engine went soft and needed replacing, used motalia Ltd. Have BSF/ whitworth studs

Richard, thanks for the lead. I’ll try and contact them today.