Herald 948 Oil Filter Conversion

I've had this project on the back burner for a while. With the original bypass filters for the 803 and 948cc Standard-Triumph engines selling at upwards of £20 - IF you can find them at all - I needed to design an adaptor to accept a more readily available oil filter.

The same filter is also in demand for some Stuart-Turner small marine engines, so we have some competition in finding them!


Oil filtration on the 803 and 948cc engine is implemented as a bypass system. This means that a small quantity of oil is diverted through the filter as it is pumped around the engine. By comparison, the 1147cc and larger engines in this family have a full-flow filtration system, so ALL of the oil passes through the filter as it is pumped.


The full flow filtration system is obviously better, but changing this really isn't an option here. The best we can do is make use of the latter system's readily available filter.


After a few months of stop-start activity, I now have a working product.




With the prototype adaptor now fully tested on one of my own Herald 948s, I have commissioned a batch of adaptors for sale. These will be available during the first week in January.

The adaptor has a retail price of £32.50, however I am accepting pre-orders paid through Paypal before December 24th, at £28.00 each, plus carriage. Carriage is £3.00 in the UK, £6.50 overseas.

Please contact me for ordering details.