Series Land Rovers
Uprating the Series 2.25 Engine
By Dixon Kenner
Things to consider when thinking about conversions. The 2.25l engine has a lot of potential locked away inside. For not too much money you can do the following to the engine and have greatly improved performance and economy:
1. Carburetor: If you have the Solex, while original and nice, the bushing wear and the full rebuild kits are very rare and difficult to find. Once you have that big kit, refitting the carb can be a right PITA, or an expensive job for someone else to undertake. The Zenith can suffer from "Zenith Disease", brought on with the top warping from age and heat. This causes internal leakage, reducing performance and mileage. The fastest and cheapest route is to toss both and put on the Weber 34ich carb. On earlier Series IIs and IIAs you will have to modify the rods controlling the carb. One pulls down, the other pushes up. You can either get the bits (the reversed spring is the most important bit) from a Series III, or purchase the conversion kit from someplace like Rovers North or Atlantic British. You will also need to purchase an adapter piece as the Weber and Zenith operate at ninety (90) degrees from the Solex. (Series IIIs obviously do not need this modification)
2. Camshaft. You can change the cam for a later 2.5l cam and get better top end torque with no loss at the bottom end.
3. Cylinder Head: If you have the earlier 7:1 cylinder head, you can have .100 milled off and increase the compression to 8:1. It is possible with later heads of the 8:1 variety to mill further and try to get towards the 9:1 compression ratio. Reliability should not be affected.
4. Exhaust. Dump the cast iron exhaust manifold and put in a long branch, possibly, tuned exhaust manifold. The downside is the lack of heat to the intake manifold to warm the incoming fuel/air mixture and help performance in that fashion. THis system can also be fitted in a more free flow fashion to get the exhaust gasses moving a little more freely.
Bear in mind when done. While still essential stock, it is still a 2.25l engine. There are "performance" engines available. Rovers North makes one, Turner (UK) and ACR (UK) also have them available. They are tunes, ported and otherwise tweaked. However, the cost is such that conversion kits like the Robert Davis Conversion are equivalently priced. As the saying goes "you pays your money and makes your choice". As always, improving brakes regardless is always a good idea. Sometimes it is more important to stop that get going.