On 5th June 1926 E. Hinnesy of Petone, Wellington, wrote his name on the inside of his 1925 copy of The Book of the Triumph by E. T. Brown. Evidently he wanted to make sure that should he lend it to somebody that it would find its way back home.
From that copy I have extracted a section on the Triumph models for 1925 that could prove quite helpful to owners or restorers. It is 10 pages and includes all the models like the Triumph Junior, a 2 ½ hp 2 stroke, the 3.46, 4.94 and 5.50 hp sv models. The OHV 4.99 hp 4 valve Ricardo model is also included and was named after its designer Sir Harry Ricardo. A sporty model that was made from 1921 to 1928 it was well ahead of it time and proved very successful in the sporting arena. Sidecars are also included within the chapter. Unlike most ordinary sales catalogues this chapter has a good description of the machines which so many model catalogues lack.
Photo – Triumph 4 Valve Ricardo engine and its famous cylinder head.
An interesting read is on the Triumph 3.46 hp model. This was an early venture by a manufacturer into unit construction. Whereas most machines of the time had a separate engine and gearbox connected by a drive chain the 3.46hp model was a unit engine and gearbox with a primary drive by gears.
Photo – Right Hand Side of the 3.46hp Engine Unit.
Click on the sidecar below to see the model selection.
It is a 1.2M PDF so you will need Adobe Acrobat Reader to view it.
For those of you who are after the more technical information on the engines like valve and some ignition timings the manual offers up the following –
1925 Triumph Valve and Ignition Timing
| Model | 3.46hp | 4.94hp | 5.50hp | 4.99ohv |
| Exhaust Opens | 54 Degrees BBDC | 14mm BBDC | 16mm BBDC | 1” BBDC |
| Exhaust Closes | 12 Degrees ATDC | 0.5mm ATDC | At TDC | 7/32” ATDC |
| Inlet Opens | **23 Degress ATDC | At TDC | At TDC | 1/32” ATDC |
| Inlets Closes | 34 Degrees ABDC | 11.5mm ABDC | 9.4mm ABDC | 15/16” ABDC |
| Tappet Clearance – Inlet
-Exhaust |
0.009”
0.009” |
0.004”
0.008” |
0.004”
0.008” |
Unknown. |
| Ignition Timing | 8 mm BTDC | 7 mm BTDC | 4.7 ¬ 6.4mm BTDC | 3/16” ¬ ¼” BTDC |
** Inlet tappet set at 0.0625” for timing engine only.