Grand Prix 250
Main Motorcycle: Triumph T140V 1976
Join Date: Jun 2008
Location: West Midlands UK
Sorry Caulky, but the some of the info you provided needs correcting.
The 2 inner studs are 5/16 diam and sleeve nuts with 3/8 a/f hex drive.
These need a dry torque setting of 16 ft lbf.
The inner rocker studs are 3/8 diam and sleeve nuts with 3/8 a/f drive and need a torque setting of 18 ft lbf.
They need the hex driver tool, or a hex key, 3/8 ring spanner in a torque multiplier mode. I made a hex key and 1/2 sq drive to go straight into the torque wrench as the head room between rocker box and frame is not enough. Removal of the rocker boxes is a least favoured option as all gaskets will need to be disturbed and renewed.
The outer hex head bolts are 9/16 a/f and are torqued to 18 ft lbf.
The service info for torquing a new composite gasket is tighten all 3/8 to 22 ft lbf and 5/16 studs to 18 ft lbf, fire her up to full temp. When cold they should be retorqued to the 18 for 3/8 and 16 for 5/16.
Reset the tappets and after 500 miles, retorque the head again to the same values.
It also begs the question whether the cylinder head gasket, having leaked, can be trusted to seal at all after all this work has been done. If the original overhauling was incorrectly carried out the head may be warped or studs stretched?
If you were to look at the sealing area between the 5/16 studs and the bores, you'd appreciate that little needs to go wrong and it all goes wrong.
i don't want to sound unduly negative here, but this is why we have forums to share opinions.
All the best with whatever you choose to do.