Anyone help please ? Need sizes of the cylinder head bolts which clamp rocker box onto head gasket. 1952 iron head model 7 . The three at front mainly as they require helicoil .
John
Also anyone know of decent…
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Threaded Holes â Iron Hea…
Threaded Holes â Iron Heavy Twin Heads.
There are 6 different threads sizes used in total on this particular head.
Most threaded holes are tapped Cycle at 26tpi (with 60 degree thread angle) apart from the exhaust ports and the oil feed inlets.
The 3 head/barrel studs are 3/8 Cycle x 26tpi both ends as is the headsteady centre stud hole.
The oil feed inlets are 5/16 BSF x 22tpi.
The inlet rocker cover stud hole is 5/16 Cycle x 26tpi.
The intake port manifold stud holes and rocker spindle plate screw holes are both 1/4 Cycle x 26tpi
The exhaust rocker cover stud holes 1/4 Cycle x 26tpi.
Exhaust ports are 1-15/16 x 14tpi. The factory shop manual technical specification appears to be in error.
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Previously Phil Hannam wro…
Previously Phil Hannam wrote:
Threaded Holes â Iron Heavy Twin Heads.
There are 6 different threads sizes used in total on this particular head.
Most threaded holes are tapped Cycle at 26tpi (with 60 degree thread angle) apart from the exhaust ports and the oil feed inlets.
The 3 head/barrel studs are 3/8 Cycle x 26tpi both ends as is the headsteady centre stud hole.
The oil feed inlets are 5/16 BSF x 22tpi.
The inlet rocker cover stud hole is 5/16 Cycle x 26tpi.
The intake port manifold stud holes and rocker spindle plate screw holes are both 1/4 Cycle x 26tpi
The exhaust rocker cover stud holes 1/4 Cycle x 26tpi.
Exhaust ports are 1-15/16 x 14tpi. The factory shop manual technical specification appears to be in error.
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Also anyone know of decent helicoil kit for use with my model 7 engine