A-series head bolts are designed to be reused; they are not Torque-To-Yield (TTY) bolts.
Retighten cylinder head bolts every 24 months or 24000 miles whichever comes first.
600 mile service 24 months/24000 miles
See Changing Head Gasket for torque specifications and procedure.
BOLT-FIXING CYLINDER HEAD SHORT [9 needed, 97 mm length] 11056-18001 36 lb ft [Original use: A10 & A12] 11056-H1000 43 lb ft [original use: A12] 11056-H2301 58 lb ft [original use: A12GX]
BOLT-CYLINDER HEAD, TO OIL GALLERY [1 needed] 11057-18000 11057-H1000 'T' 11057-H2300 '13' for 1967-1973 engines [97 mm length] 11057-H5700 '13' for 1974-up engines [111 mm length]
Bolts are the same for A12/A14/A15, but A14/A15 require the stronger bolts (marked '13').
1973 A12 (early engine, upgraded H1000 bolts) Torque: 40-43 ft-lb CENTER BOLT: 8 mm central portion (head marked 'T') OTHER BOLTS: 9 mm
Better to use the GX '13' center bolt, which is high-tensile chromoly V steel
"13" bolts were first used on the twin-carb A12GX Engine, as opposed to single-carb engine bolts. "13" bolts can be used with any early engine (they are simply stronger than the earliest bolts).
Note that A12/A12A/A13/A14/A15 all may use the '13' bolts, but the center bolt differs between early engines and late engines.
Center bolt 11057-H5000 and 11057-H5700 are interchangeable
Original Lo-torque bolts (B10 & early B110 -1172) - 36 ft-lb * 11056-18001 BOLT-FIXING CYLINDER HEAD SHORT * 11057-18000 BOLT-FIXING CYLINDER HEAD LONG * 11058-18000WASHER-LOCK FIXING CYLINDER HEAD
Newer medium torque bolts (1272-) - 43 ft-lb * 11056-H1000 BOLT-FIXING CYLINDER HEAD SHORT (9 needed) $2.90 * 11057-H1000 BOLT-FIXING CYLINDER HEAD LONG [Center bolt] $2.51 * 11058-H1000 WASHER-LOCK FIXING CYLINDER HEAD $2.28
A12GX, A12T, A12S, A13, A14, A15, A12A - 58 ft-lbs * 11056-H2301 HEAD BOLT SHORT (9 needed) $3.96 ** NOTE Some newer lo-power (round port) A12S are spec'd for 11056-H1000 ** Also used by Z16/Z18/Z20/Z22 (10 per engine) * 11057-H2301 BOLT-CYLINDER HEAD LONG, TO OIL GALLERY (TO 6/73) $3.88 ** one needed * 11057-H5000 BOLT-CYLINDER HEAD LONG, TO OIL GALLERY (FROM 7/73) $4.03 ** one needed ** Also used by Z24, KA24E, NA20P (10 per engine) * superceeded 11057-H5700
head bolts Cro-Mo-V steel 13T
Lock Washer * 11058-H1000 WASHER-LOCK FIXING CYLINDER HEAD -8504 $2.28 * 11058-21002 Washer Cyl Head 8504- $2.57