QUESTION: What kinds of carburetors fit my 2.25 Land Rover engine?
REPLY: There are currently 5 carburetors commonly found on 2.25 Land Rovers:
Solex 1 barrel (with or without pre heater), stock fitment 1958-’67
Zenith 1 barrel (emission model or straight), stock fitment 1967-’85
Rochester BV 1 barrel (US after market) fitted to 215, 235 Chevy I-6, 1950’s.
Weber 34ICH 1 barrel (after market replacement)
Weber 3236DGV 2 barrel (after market, similar to the 3234DMTL fitted as standard, 1985-’93 on 2.5L engines)
Carb sizes by airflow numbers:
Model Venturi diaFlow
Solex 28mm 115 cfm
Zenith 27mm 127 cfm
Weber34ICH 29mm 138 cfm
RochesterBV 31mm 167 cfm
Weber323627 27mm 191 cfm
(thanks to Jim Allen for the data)
Of the 5 listed above, only 3 are currently available new: Zenith 36IV, Weber 34ICH, and Weber 3236DGV.
For ease in installation and reliable service, the new Zenith is best, and one of our biggest sellers. If replacing Solex or Rochester, an adapter base is required when using the Zenith. The Zenith is no longer available in 36IVE (emissions) form, with the fuel shut off solenoid. In some areas with mandatory emissions testing, these are required. Waivers due to inability to supply can be obtained. Rebuild kits are moderately priced. Smaller Zenith jets are available for higher altitudes (above 5,000′).
Best overall performance (all of BP’s employees have used it, either now or in the past). This is a simple, robust carburetor, good off road, easy to service, allows use of the stock or K&N air filters, and really improves top end performance over the Zenith or Solex (top end power is almost the same as the Weber 2V). The Rochester BV carburetor came on several sizes of GM six cylinder engines. The carburetor was equipped with a different size venturi for each GM engine size. The venturi sizes are 30.9mm, 33mm and 38.5mm. The carburetor that you want came on a 235 CU inch 6 cylinder equipped 1954 Chevy. It has the 30.9mm venturi, a manual choke and a sleeve type top that fits the neck of a Land Rover air cleaner. This carburetor is still available as a rebuild. Your 2.25L engine will not run properly with carburetors that have the larger venturi sizes. This is the best option of all. It is easily adapted, and works well. Parts are cheap and readily available despite their age. The Rochester will need to be rejetted. A 48 to 52 main jet will work in most cases, depending on altitude and engine condition, and the model carburetor secured. Start with 50 to 52 for primarily low altitude driving or 48 to 49 for primarily high altitude driving. Too lean a mixture will shorten the life of your valves.
The Solex is a complicated piece, and expensive to service. But while it’s top end power is low, the slow speed characteristics are really very good. And the heated models are very useful in snow or cold climates. Not our favorite, but they do have some areas they do well: if you do a lot of snowplowing, this is your carburetor! The Solex was remanufactured in a limited run a few years ago. There may be additional manufacturing runs in the future. New versions do not have the electric heat feature. Rebuild kits are available but expensive.
The Weber 34ICH is a generic carburetor designed to be closely adaptable to individual engines. This means that the jetting is complicated enough to require an expert to get it tuned as close as possible to your engine’s needs. However a 165 Main Jet , 190 Air Correction Jet and F6 Emulsion Tube will normally get a stock 2-1/4L engine running acceptably well at or near sea level. At around 7000 feet try a 155 main jet. Webers tend to be sensitive to altitude changes and need to be leaned out at around 5000 feet for proper running. While the 341CH has more top end power than the Zenith it is the most susceptible to dirt and water in the fuel and can frequently cause problems if the fuel is not clean and well filtered. The Weber’s main jet is located at the bottom of the float bowl, where it can be clogged with gunk. The Zenith and Rochester have their main jets supported from above, and are less susceptible to clogging and moisture.
When customers ask about the 34ICH we normally recommend the Rochester BV. The top end performance of the 34ICH is less than the Rochester, it is harder to jet and more often a source of running problems. However it can be an efficient good performing carburetor if properly jetted for your driving conditions and your fuel is kept very clean and free of moisture.
While being similar to the no longer available 2 venturi Weber carburetor that came stock on the Land Rover 2.5L engines it is a generic replacement carburetor This carburetor operates as a single venturi carburetor when the engine is loafing and opens the second venturi when the engine is working hard.. We feel that this carburetor provides too much flow for a stock 2-1/4 L engine. On a stock engine it has a stumble between the primary and secondary opening as a result of low manifold vacuum. Most people who have added one do not notice a power increase and will often see a drop on fuel efficiency. Like the 34ICH, the 3236 is sensitive to altitude changes and has the main jet located at the bottom of the float bowl, where it can easily be clogged with gunk: However, if you are willing to spend the time to properly jet this carburetor it can work very well on an engine that has been modified for additional power. At a minimum we would recommend, 8:1 compression, the 2.5L cam and a size larger diameter exhaust system with a free flowing muffler.