On 14 November 1940, it was the night that the German air force was launched on a mission to obliterate Coventry. Triumph's factory was destroyed and that was the end of the 3TW
An old foundry in Warwick was converted into a machine shop and production of Army service parts was started. It was uphill work with very limited accommodation, but progress was made and by June 1941, complete machines were coming off the track once more. (Edward Turner moved to BSA around this time). The machines coming off the track were not only the side-valvers that had been produced previously, but OHV 350s based on the pre-war 3H, and renamed 3HW. The only major difference was that whereas the 3H and Tiger 80 had separate alloy rocker boxes, the 3HW rocker boxes were cast integrally with the head.
3HW has been used in North Africa and India, but also in Greece. Greek Army used those machines from 1942-1952. The only problem that 3HW machines had in N.Africa and India was air cleaner, the dust soon put paid to the bore and rings, no air cleaner being fitted. A couple of thousand miles was about the limit before major servicing was required. the same thing happened to the G3/L Matchlesses. Why no air cleaners were fitted to bikes going into appallingly dusty conditions is a question that could only be answered by some official in Whitehall,I suppose. Maybe he was not even awere that it was dusty in the dry season in that part of the world. I'll warrant the Japanese had air cleaners!
Model_______________________________________3HW
Type__________________________O.H.V. Single Cyllinder
Cubic Capacity_______________________________343cc.
Petrol Tank Capacity_____________________3.1/8 Gallons
Oil Tank Capacity_________________________3/4 Gallons
Oil in Chaincase_____________________________3/4 Pint
Bore______________________________________70 mm.
Stroke_____________________________________89 mm.
Tappet Clearance (Cold)_____________Inlet______1 Thous.
______________________________Exhaust_____1 Thous.
Lubrication_______________________________Dry sump.
Top_________________________________________5.80
Third________________________________________8.40
Second_____________________________________13.30
Bottom_____________________________________17.80
Con. Rod--Side play_______________________.003"-.015"
_________Big-end diameter____________1.4620"-1.4623"
Crankpin-Bearing diameter_______________.9620"-.9617"
Timing Shaft diameter (bearing position)_____.9995"-1.000"
Drive Shaft diameter (bearing positions)_____.9995"-1.000"
Camshaft Bush diameter (internal)_________.5610"-.5620"
Idler Gear Bush diameter (internal)_________.4995"-.5005"
Tappet Guide diameter (internal)___________.3740"-.3750"
Tappet diameter (external)________________.7495"-.7500"
Bore diameter________________________2.7555"-2.7560"
Max. permissible wear before reboring______________.008"
Piston Clearance-Top of Skirt_______________.008"-.0085"
_____________Bottom of Skirt_____________.004"-.0045"
Piston Rings-Gap_________________________.010"-.014"
____Groove Clearance, Compression_________.001"-.003"
____Groove Clearance, Scraper____________.0005"-.0025"
Valve Guide diameter (internal)_____________.3120"-.3130"
Valve Stem diameter-Inlet_________________.3095"-.3100"
_________________Exhaust______________.3083"-.3088"
Valve Seat Angle_________________________________45
Tappet Clearance________________________________Nil
Rocker Bush diameter (internal)____________.5620"-5630"
Rocker Spindle diameter__________________.5605"-.5610"
Timing-Inlet Opens,B.T.C.______________________47.1/2"
______Inlet Closes, A.B.C.____________________68.1/2"
______Exhaust Opens, B.B.C._________________69.1/2"
______Exhaust Closes, A.T.C._________________46.1/2"
Timing, fully advanced____________________________3/8"
Contact Breaker Point Gap______________________.012"
Sparking Plug Point Gap__________________.015"-.018"
Body, Scavenge diameter (internal)______.37475"-.37525"
Body, Feed diameter (internal)__________.31225"-.31275"
Carburettor Nr:___________________MT12/AM/276AD/1J
Main Jet______________________________________150
Slide_________________________________________6/4
Needle Jet____________________________________107
Needle_________________________________________6
Clutch Rod, Lost Motion_______________________1/32"
Clutch Cable, Lost Motion______________________1/16"
High Gear Bush-Layshaft diameter (internal)___.7498"-.7505"
______Mainshaft diameter (internal)_______.8115"-.8125"
Clutch Spring, Free Length______________________1.5"
Girder fork
Spindle diameter_________________________.435"-.436"
Spindle Bushes diameter (internal)____________.437"-.438"
Tyre Sizes____________________Front & Rear___3.25-19
Wheel Base_________________________________52.1/2"
Overall Length__________________________________82"
Overall Width________________________________28.1/2"
Plug Point Gap__________________________15-18 Thous.
Contact Breaker Point Gap___________________12 Thous.
NOTE. - All bush measurements are finished sizes in position where the bush is not floating.