It depends on the bolts. The A10 and early A12 bolts probably cannot take the higher torque.

The ones with "A13" on the bolts should take either of the higher torque specs.

With an original A12 block, I would use the middle torque spec. Just in case the block threads aren't strong enough. With a 1974-up block and "A13" bolts, I would use the higher torque.

yeah im using a12 bolts so yeah. still keen to hear other peoples opinions

A B120 A12 uses 51-54lb-ft of torque to fasten the head according to factory service manual.

i'm with you beattie, check the part # on the bolts and torque accordingly

I would go the head torque.

After all that is what your squashing down. Still surprised their different tho!

Or should the question be what head bolts are you using? They may have different yeild torques!

i was reading in the tech section and noticed that the a12 and a14 engines have different torques for the head. now my question if im using a14 head on an a12 bottom end which torque do i use

(engine cold)engine torque lb ft torque Mkg comments
A12 33-36 ft-lb 4.5-5.0 Mkg (to engine # A12-470084)
A12 40-43 ft-lb 5.5-6.0 Mkg (from engine # A12-470085)
A13 51-54
A14 51-54 ft-lb 7.0-7.5 Mkg