I need to get some bolts chromed, but cannot find the thread size, They are the bolts that hold the head down, can someone tell me the size of the thread please.

Got no spare nuts to try on the thread, I know someone will have the answer, I tried 5/16wit, but I think its a fine thread.

Davo.....

Are you talking head bolts or head stud nuts? You mention both.

The head stud fine thread nuts are 3/8 UNF, although the thread into the block is 3/8 UNC.

Whitworth have no place on a mini, even though they fit. The thread angle is different so the contact is very poor and will not hold a torque properly.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

If they are the head bolts (not studs) fitted to the 1100 motors from about 1969 then they won't need to be chrome plated to make them brittle.
Throw them out before you break them.

I would NOT chrome the head bolts or studs. Chroming process causes hydrogen embrittlement, which is why important fasteners are never chromed.... and a head bolt or stud is one of the important on a Mini.

If it has bolts they are prone to breakage where they screw in the block- I'd replace with studs, and if you want ones that are Da Bomb, with 12pt nuts, buy the ARP kit.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

This is the reason for the querie

Steve(Brickworx) sent me over a new set of leads, because No1, was arching in the top of the alternator, and they have a stainless steel covering with a loop on the top end and I believe that they have to be bolted onto the top of the studs, so if I put another nut on top of the one that is already there, that should earth them and hold them in place.

Thanks

David.

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