Tuning su carburettors pdf

Sep 28, 2011 you can also send your carbs to him for overhaul. Su carburetors are marvelously simple devices that work wonderfully well, despite everything you have heard or even have experienced on old, wornout british cars that are decades away from the condition they were in when they left the factory. Oct 04, 2015 today i will discuss tuning of su carburetors. The vast majority of modem spark ignition internal combustion engines rely upon carburetters to provide them with the finely atomized fuelair mixture which is necessary to enable them to perform satisfactorily. Make sure all components of the ignition system timing, plugs, points, and wires are properly adjusted and working well, and that the valves are adjusted to specification before trying to adjust the carburetors. Some sus also have exhaust emissioncontrol devices to comply with antipollution laws. Operation bad wolf ep 20 servicing the su carburettors. Su su carburettor photos and information posts welcome to the relaunched carb. The varajet carburettor used on many vauxhalls and opels is a hybrid between fixedjet and variablejet for example, su types.

Only recently did i discovered what the su designers had been up to all these years, and it certainly opened my eyes to the potential of su carbs. Important notice regarding tuning before you retune your su any su on any engine including british built sus on mgs etc please be aware that one of the most common ways to burn out the exhaust valves on an engine fitted with one or more sus is to lean out the mixture because you were. The su carburettor is a relatively simple design but has proved to be very effective. Often underrated, it offers versatility and reliability due to being analogue and the vast array of. Righthand steered 1800 cars are also fitted with this type of carburettor. The following should be checked on the engine prior to setting up the carburetor to determine if the situation will lend itself to optimal timing, or. It is as sensitive to dirt and sediment as any fixedjet carburettor, and needs careful cleaning about once a year. Follow the instructions in the tuning guide for establishing a base line, make sure linkage is loose and reset idles making sure that the fast idle screws are clear of the fast idle cam. The often underrated su offers good versatility and reliability. Don jacksons opinion is that the standard es needle for the t series is far too rich and the eu is better. Su carburetters are the worlds sole manufacturer of genuine su carburettors, fuel pumps and spares. The trick to tuning su carbs is to understand that there are two things you need to get right.

Covers tuning tips and techniques for su carburetors as well as all su fuel pumps for numerous classic cars, including the mini cooper, sprite, bentley, jaguar etype, jaguar mk 2, daimler v8, land rover, mgb, rolls royce, tr4 and tr7, spitfire, rover and volvo 1800. Preparation setting up and tuning an su carburetor is based on the premise that both the engine and the carburetor are in good shape. Tuning su carburettors sterling british motoring society. The float chamber maintains a constant level of fuel at the jets and cuts off the supply when the. Being an oftvoiced question on the message board, i thought id share it with you. These instruments are essential when tuning vehicles equipped to conform with exhaust emission regulations. This is intended to grow over time to become a very useful resource for all models of su carburettors, as fitted to many british classic cars such as jaguar, mg, morris, austin, and more. Please click on an article name to go to the actual article or click on the relevant image below to go to the first page in each category. Technical editor back to basics, for those of you who are fairly new to the register and tso, is a series of articles designed to help the wouldbe backyard mechanic cope with basic automotive maintenance procedures. The oil is there to slow the movement of the piston. With the all plastic floats washers are added or subtracted from under the needle valve to raise or lower the fuel level, more washers give. Tuning su carburettors including full needle charts, 1968 speed and sports publications ltd acorn house, victoria road, acton, london w. This one is more like basic su adjustment for happy driving.

Pdf su carburettors tuning tips and techniques download. It is the function of the carburetter to provide good atomization and the. Tuning su carburettors even though a large proportion of modern motor vehicles are now equipped with s. Su carburetors were widely used in automobile vehicles from much of the twentieth century. Moss part numbers 215 and 2145 are two such guides. If after resetting idle, one carb still appears to draw more air, you most likely have an internal engine problem. These instructions do not cover tuning su carburetors. There are four distinct phases to tuning su carburetters carbies. Here, then, is an explanation of the principles of tuning, fol lowed by a. Before tuning the carburettor, carry out all the checks in checking and. Not having a go at your technician but i trained many of them when i was at bl who did not really understand. To achieve the best results when tuning, the use of a reliable tachometer. The idiots guide to tuning su carburetters setting of. The idiots guide to tuning su carburetters there are four distinct phases to tuning su carburetters carbies.

Adjust the pegs on the ends of the interconnecting linkage until there is approximately 116 inch clearance free play before the peg contacts the slot on the carburetor tab. For the h4 carburettor the position range is p1 to p10. Skinner union carburettors, many motor mechanics still encounter difficulty when tuning and adjusting these relatively simple units. Su carburettors tuning tips and techniques available for download and read online in other formats. Hence it is fitted with racing cars and in most of the scooters and motorcycle. Ive been meaning to write this up for some time, ever since i did the su performance tuning 101 a few months ago. Article 7 adjusting the carburators new hill garage. Please click a category heading on the left to show or hide the articles in the category. Sus specification for the fuel level in the carby is 38 inch below the bridge. And no amount of tuning with that needle is going to make it right. The design was in quantity production for much of the twentieth century. Paul is almost anal about tuning and feels symptoms that completely elude me.

Su carburettors can theoretically perform better than modern computer controlled fuel systems. Unlike other types of carburettor, which have fixed jets, the su has only one jet, so the mixture setting affects the engine throughout its speed range. Feb, 2018 1968 mgc complete su hs6 carburetor tune. There will be those who disagree with this method of carb adjusting and i will agree this is not the only way to adjust su carbs as i have used different. Su carburettors are a brand of carburettor of the constantdepression type. Tuning your carbs need help figuring out which skinner union su needles you need to keep your car running right in all throttle conditions. This position is set when the carburetter is tuned for idling. A few years back, a genius over at developed a handy charting and searching tool for just that purpose. The method in principle could be used for most su carburettors including the mg ytype or the mga or mgb. The b 20 b engine in the l20 and 140 models is fitted with two horizontal carburettors of type su hs 6. This is due the su being analogue and the vast array of needle profiles available. Keep all sources of ignition and open flame away from the vehicle. Unfortunately, following discussions with many people, the operational principles of this carburettor appear to be poorly understood. Using a ruler and a finepoint pen, start from the mounting shoulder and make fine lines across the needle at precise 18th inch increments.

If you want a copy of the pdf file i made with all of the tuning instructions. With the earlier and the latest floats the metal hinge is bent up or down to get the desired fuel level. Before tuning the carburettor, carry out all the checks in checking and cleaning an su carburettor, and bring the engine up to normal working temperature. Setting up and tuning su carburettors tools screwdriver spanner adjustable spark plug spanner jet adjusting spanner early cars carburettor damper oil length of tube or hose carb balancer optional the su carburettor is a simple design proven to be very effective. Just as in a su needle catalog, we first need to have accurate measurements of the needle needles, if a multicarb engine before starting any mods. The su carburettor is a simple design proven to be very effective. Setting up and tuning su carburettors tools screwdriver spanner. Please click on an article name to go to the actual article or click on the relevant image below. Balancing hif su carburettors morgan owners club of australia. The first is to set the fuel level in the float bowl, the second is to centre the needle in the jet, but only with fixed needles, not spring loaded ones, the third is to balance twin carbies.

Rivera primo su eliminator carb kit harley davidson 1955 to 2006. Also check the level of oil in the dashpot the domed piston chamber at the top of the carburettor. Charles bishop i originally wrote this up to assist a fellow xker in adjusting the su s on his jag i received about a halfdozen requests to be included in the offlist mailing please note. Amal carburetter hints and tips how the carburetter works the carburetter proportions and atomises the right amount of petrol with the air that is drawn in by the engine because of the correct proportions of jet sizes and the main choke bore. Such carburettors are of the variable choke type and their principle of operation is. Recheck fuel mixture, and carburetor synchronization.

Joe is probably the most highly recommended expert on su carbs in the us. With the all plastic floats washers are added or subtracted from under the. There are basically 4 adjustments that can be made to the su. Tuning the su carburettor on the tseries mg totally ttype 2. These are also used in aircraft engines including the early versions of the rolls royce. Tuning includes mixture adjustment, idle speed adjustment, and synchronization. It is assumed that your carbs have been properly rebuilt and the jets centered. Download pdf su carburettors tuning tips and techniques book full free. The technical articles for su are divided into categories.

The main advantage of su carburetor is the rapid response during accelerating. Setting up and tuning su carburettors classic car hub. Su carburetors have a minimal number of moving parts and are easy to tune, providing of course you understand the operational principles. Since there is already a very good source of starting pointsapplications for fixed needle carbs, this is for those floundering about in the wilderness that is the biased swinging needle example of the breed. Rivera primo su eliminator ii carb kit harley davidson 1955 to 2006.