SELECTING A CARBURETTOR FOR YOUR ENGINE

There is a lot of mis-information circulating which can create a huge amount of confusion when it comes to selecting a carburettor upgrade for your vehicle. With this in mind I have added this overview addressing some of the mis-conceptions surrounding suitable conversions.

When it comes to carb upgrades there seems to be a general assumption that the bigger the carb the better. This is simply not the case. Fitting too big a carburettor will result in an engine that will at best run poorly, return awful fuel consumption and generally operate terribly. Worst case scenario is it will not run at all. We have had more than one email asking us if we can supply a Holley 350 kit to suit a Datsun 1200. This sort of conversion - even IF it was physically possible would be nothing short of a nightmare in reality with engine flooding, woeful economy - basically the car would run worse then if it was fitted with a stock carb.

Carburettor selection must be made with several criteria in mind. First of all the engines state of tune needs to be considered. Is the engine stock or modified? All engine modifications need to be considered ranging from a simple set of extractrors right through to a big cam or a turbo upgrade. Secondly the vehicles use needs to be considered. Is the car a daily driver or is it a dedicated circuit racer or drag car? If the car is a daily driver is fuel economy the main consideration or is outright performance required? (Or is a good balance of both the desired result?) In the case of commercial vehicles like Pajeros, Hilux and Jackaroos the vehicles use is critically important. A 4x4 that sees regular off road use will require a different carburettor set-up to a street driven cruiser.

While these may seem like straight forward questions this sort of information is critical in order to both selecting a suitable carburettor/ carburettors and also to having them jetted correctly.

The importance of jetting can not be overstated. Entire books can be written on the subject - though its not my intention to delve into in-depth equations here. What I can't emphasize enough is that the more information you can supply; the better when it comes to making a recommendation for your car. We were recently giving advice to a customer who advised he had a standard 1600 engine. As we were about to send off a carby it came up in conversation that the engine had an aftermarket turbo fitted! This sort of information is critical - although this is an extreme example it does go to show how important communication is. In this case we stripped the carby apart and re-calibrated it to suit the turbo. Without this modification the carb could not possibly have operated to its full potential.

So that being said is there a simple, bolt on economical performance upgrade to suit a standard, mildly worked or highly modified 4 cylinder vehicle? Yes there certainly is! We have built Webers for use on everthing from 3 cylinder turbocharged engines right up to big sizes but we specialise in 4 cylinder vehicles. Whether you have a Datsun 1000, Suzuki Sierra or a Gemini drag car there is a setup available to suit your needs.

In the case of a standard or mildly modified engine a simple and effective conversion is to upgrade to a downdraught Weber. We can supply a full conversion kit with everything needed including adaptor plate kit, linkages, airfilter and of course purpose built carburettor. The best model carburettor to use will vary with application taking into consideration the factors outlined above.  I am more than happy to make a recommendation for your application. Please email me the information regarding your vehicle and I'm happy to go through the options with you.

In the case of a worked engine or those looking for a high powered conversion there are again many options. These range from a large downdraught weber, a single sidedraught, or even twin carbs. Again all factors need to be taken into consideration in order to select the best set-up for your vehicle.

The beauty of weber carbs is that there is a model to suit virtually all applications. These carbs are fullt tuneable and can be set up and jetted specifically to suit your needs. Don't be fooled by anyone trying to "upsell" you into a bigger carb. Bigger does NOT mean better when it comes to an upgrade. Secondly provide an much information as you can and don't be afraid to ask questions. The more info you can supply the more tailor made the recommendation (and ultimately the carburettor) will be.

Hope this helps!

(c) GEM PARTS AUSTRALIA 2007