Lots of questions when reinstalling

I’ve been pestering my machinist, the one that built the engine for me and he swears he doesn’t have them. He called around and found someone that has (supposedly) the correct thread and length. They’re supposed to get here by Tuesday. He didn’t ask about the hardness, just figured that it’s a step in the proper direction.

This is my favorite US source for British screws.


They have good thread charts worth downloading. I printed a set for the shop.

Moss also has them but higher priced, probably listed under MGTC.

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Just beware of using any fixings listed for MGs (incl. Morris and Wolseley) up to the end of the T series in 1955, as all engine threads were/are metric but with Whitworth hexagons. You can read the history of this but it is part of the fallout from WW I which involved the transfer of tooling from France to the UK to avoid seizure or destruction. Threads elsewhere are the usual standard of BSF/Whitworth/BA.

Peter L

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Motalia stock a large range of stainless steel BSF nuts, bolts and studs:


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In Moss search for screws; they are under MGTC/D/F and Austin Healey, Garage and Tools, Hardware.
3/8 BSF x 3/4" is 320-560
3/8 BSF x 1" is 320-580

Rob, would those be normal 5 hardness or possibly the 8?

The grade of bolt / fastener is the tensile strength of the bolt / fastener, use the correct bolt for the application.

  • Grade 5 – Unlike grade 2 bolts, grade 5 bolts feature 5 radial lines. These bolts are manufactured from medium carbon steel. These bolts come in two different size ranges – 1/4″ to 1″ and 1″ to 1 1/2″, which have the proof load of 85000 psi and 74000 psi respectively.
  • Grade 8 – Grade 8 bolts are made from medium carbon alloy steel. The bolts of this grade feature 6 radial lines. The nominal size of the grade 8 bolts can be from 1/4″ to 1 1/2″. The minimum yield strength of this grade bolt is 130,000 psi. A maximum of 120,000 psi of tensile force (proof load) can be applied to grade 8 bolts.


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A more careful look; the end is machined spherical, rather than just whacked off in the screw forming machine, as you normally find with cheap bolts.
Length including spherical end is 15/16" as Roger said, 7/8" of threads.
Hex head standard 3/8BSF size and is stamped 80 or 08. No other markings. This may be some British strength standard of the 1940s.

I now believe the C.514 number means these were carefully weighed and balanced, as you would expect in rotating machinery, rather than using off the shelf screws with an FS.xxx number.

I’m having severe muscular skeletal pain in the chest and shoulders due to lifting the SS gas tank out of the trunk with a couple of gallons of gas in it 2 weeks ago. The prescription medicine has made me irritable, so some of my recent responses may have been less than charitable, for which I apologize.

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Rob, not to worry. Nothing sounded cranky. I just appreciate you and the others chiming in on my queries. I’ve been playing with 1930 Cadillacs for so long, I had forgotten my time with a MK 2 of 30 years ago. Seems like I’m starting from scratch with British machinery. I thank you all for your help.
I hope your pain lightens up soon!