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| Rocker oil feed | The two oil pipes from the front of the timing chest on the '39/'40 twins
were routed as in the picture, including a couple of little straps formed
from flat strip. A restrictor arrangement in the form of a brass casting bolted to the front of the timing chest was incorporated to regulate oil flow. On the singles a four-way union on the end of the exhaust rocker shaft was used, and this system continued with the early twins although there is evidence that the brass bodied restrictor unit arrived before the end of the '38 season. The oil drain from the rockerbox on the singles was achieved by two different methods. Either a 'Y' pipe to a threaded boss in the crankcase at the base of the barrel, or, two separate pipes that bolted to the barrel studs themselves and drained through drillings in them. The chronology is unclear as I have found 1938 cases with both arrangements. The advantage of the drilled studs seems to be that the crankcase casting would be the same as the side-valves (not needing the extra boss). Far more confusing is the many attempts at solving the crankcase breathing arrangement on the singles. From 1936 - 39 I've found no fewer than four different methods including the odd screwed breather in some early engine shaft sleeve nuts. I suspect that oily engines were quite a problem with the big single. |
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| The Achilles heal of the Tiger 90 and 5H, the broken rockerbox mounting tabs, occurs when bolts are loosened in the wrong order and the valve springs are under tension, forcing the box up at an angle as it is loosened. | |
| Twin cylinder camshafts | |||
| Year | Model | Inlet | Exhaust |
| 1938 - 39 1946 - 49 1950 - 52 1953 1953 1954 |
5T/T100 5T/T100 5T/6T/T100 5T/6T/T100/TR6 T100c 5T/6T/T100/TR5 |
E1485 E2302 E2303 E3275 E3134 E3275 |
E1485 E1485 E2303 E3275 E3134 E3275 |
| Twin cylinder carburettors | |||
| Model/year | Carb complete | Mixing chamber | Float chamber |
| 1938/39 5T 1938/39 T90/5H 1939 T100 1946/47/48 5T 1946/47/48 T100 1949/50 5T 1949/50 T100 1950 6T 1951 5T 1951 T100 1951 6T |
D64 (76/132) D58 D107 (76/117) D207 D212 276DK/1AT 276DL/1AT 276AE/1AT 276FE/1AT/M 276FH/1AT/M 276FG/1AT/M |
76/132M 89/116(M -'38) 76/117 276/410R 276/411R 276/410R 276/411R 276/411R 276/433R 276/432R 276/434R |
64/195 64/177 14/001B 64/192 (1AT) 64/192 (1AT) 64/192 (1AT) 64/192 (1AT) 64/192 (1AT) 64/192M (1ATM) 64/192M (1ATM) 64/192M (1ATM) |
| Single cylinder connecting rods | |||
| Part no. | Model | Year | s.e. bush size |
| E594 E658 E1134 E1401 E594T E1134T E1401T E518T E1298T E518 E1298 E1299 E1426 E1578 E1426T |
2H 3S 3H 3H T70 T80 T80 T90 T90 5H 5H 6S 2H 3S T70 |
1937 1937 1937 1937/38/39 1937 1937 1937/38/39 1937 1937/38 1937 1937/38/39 1937/38/39 1938/39 1938/39 1938/39 |
1 inch 1 inch 1 inch 11/16 inch 1 inch 1 inch 1 inch 1 inch 1 1/4 inch 1 inch 1 1/4 inch 1 1/4 inch 1 inch 1 inch 1 inch |
| Gears, all models | |||||
| Std up to 1948 | W.ratio to 1948 | Std 1951 to 1953 | Close ratio | Wide ratio | |
| Mainshaft high gear | 25t | 27t | 26t | 24t | 27/28t |
| Mainshaft 2nd gear | 19t | 18t | 20t | 21t | 18/19t |
| Mainshaft 3rd gear | 23t | 24t | 23t | ||
| Mainshaft | 15t | 16t | 18t | ||
| Layshaft highgear | 19t | 17t | 20t | 22t | 17/18t |
| Layshaft 2nd gear | 25t | 26t | 26t | 25t | 26/27t |
| Layshaft 3rd gear | 21t | 22t | 23t | ||
| Layshaft lowgear | 29t | 30t | 28t | ||
| Spark plugs specified as original equipment 1934-1958 All plugs are 14mm thread unless indicated | ||||
| Model | Year | Lodge | KLG | Champion |
| OHV models 1934-1936 | 1934 - 1936 | H1 (18mm) | 777(18mm) | |
| 'Super sports' | 1934 - 1936 | H45 (18mm) | ||
| SV models 1934-1936 | 1934 - 1936 | C14 | L777 | |
| 'Super sports' | 1934 - 1936 | H53 | ||
| 2H, 3S, 5H and 6S | 1937 - 1939 | H14 | ||
| 3H, T70, T80 and T90 | 1937 | 831 | ||
| 3H, T70, T80, T90, 5T | 1938 | 831 | ||
| 3H, T70, T80, 5T, T100 | 1939 | 831 | ||
| All models | 1946 | H14S | ||
| 3T | 1947 - 1950 | L10S | ||
| 5T | 1947 - 1950 | H14 | ||
| T100 | 1947 - 1950 | F80 | ||
| 6T | 1950 - 1953 | H14 | F80 | L11S |
| 3T | 1951 | H14 | F70 | L10S |
| 5T | 1951 - 1953 | H14 | F80 | L11S |
| TR5 and T100 | 1951 - 1953 | HLN | FE80 | NA10 |
| 5T and 6T | 1954 - 1955 | L10S | ||
| TR5 and T100 | 1954 - 1955 | NA10 | ||
| T110 | 1954 - 1955 | L11S | ||
| 5T and 6T | 1956 - 1958 | L10S | ||
| TR5, T100, T110, TR6 | 1956 - 1958 | NA10 | ||
| Primary Cases |
For 1937, the inner primary case was very similar to the previous (1936) year, and the two are interchangeable differing only in detail including a breather and the oil sealing arrangement around the gearbox main shaft. In addition, the earlier version is of a heavier construction. The outer primary too was basically the same casting as the '36 models but with some of the detailing tidied up. The most obvious identifying point for these early outer primaries is the round-boss fairing over the shock absorber assembly. For 1938 a new outer appeared with a teardrop shaped boss at the front. Unfortunately, casting numbers tended to remain the same on different cases, and so cannot always be used for identification although the outer cover is the same for singles and twins. A new inner cover appeared in 1938 for the twin cylinder engine without the shaped distance piece over the top front and remained the same until the post-war era. For 1939 the outer cover gained a tapered screw adjustor for oiling the final drive chain. All pre-war outer primaries had a hexagon headed oil level plug (same as the gearbox oil level plug) below the footrest and although this was deleted post-war the blank in the casting can still be seen. Therefore, the outer primary cover is different for 1937, 38, 39 and 46. |
| Whitworth screw lengths | |||
| Underhead length | Quantity | ||
| Timing cover, twins | 1 inch 1 1/2 inch |
7 3 | |
| Timing cover, T90/5H | 1 inch 1 1/4 inch 2 3/8 inch |
7 2 2 | |
| Gearbox | 1 inch 1 1/2 inch 2 1/2 inch 3 1/4 inch |
5 1 1 1 | |
| Primary chaincase singles | 1 inch 2 1/2 inch |
9 3 | |
| Primary chaincase twins | 1 inch 1 5/8 inch |
9 3 | |
| T100 carburettor | Probably the hardest part to find on the pre-war Tiger 100s is the correct carb/petrol pipe/tap arrangement. The carburettor body is not a big problem because as long as the critical factors are correct (left/right hand/flange fitting/bore etc.). It'll work fine because Amal famously use completely different stamped numbers on the same carb according to the machine it fitted. The unique float chamber is a mystery. I suspect it was used to save space as it gets very crowded in this area. The flexible pipes from the union to tap would have been steel-braided. The picture shows the setup with only one tap, of course there are two. |
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