(b) Turn the jet adjusting nut/screw (2) down/clockwise, to enrich or up/anti-clockwise to weaken, until the fastest speed is indicated; turn the nut/screw up/anti-clockwise until the engine speed just commences to fall. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); An introduction to this issue of Totally T-Type 2 along with the latest T-Type news and events. Example: With the speed screw set at no more than (1 1/2) turns in after contact with the stop lever; and the best idle occurring with the mixture screw set at 3 turns from the bottom, indicates the need for a larger idle jet. Inch jet orifice. However, by returning to the origins of the SU carburettor, a weighted piston, as at first designed, could be employed instead (see below). air/fuel ratio. The most basic idea to keep in mind is that the air flow and mixture are the same from one carb to the other. If the speed screw has to be opened 2 or more turns, then this is also an indication of a lean condition usually requiring greater change. We'll assume you're ok with this, but you can opt-out if you wish. Put the car in gear and apply a slight load, (AC on) and set the idle as you like it. How to Set Up and Tune SU Carbs in Easy Steps - YouTube This is the reason that the Weber should give a fuel economy improvement over most factory carbs, along with significant performance gains. I had a look at mintylamb, very useful thanks. The screw will be sensitive and should only take 1/4 to 1/2 turns to achieve the idle speed you like. 2021 TR Register (TR Owners Club Limited) The figure of 217 is proportional to the actual annular surface area, and thus the fuel flow rate, for this needle at P5. 0000003044 00000 n My engine is as far as I found from 1970, but with a newer head from 1974, not sure if a previous owner skimmed a bit off the head or even changed the cam, probably impossible to know without taking it apart. But I noticed (or maybe it was just in my head) that the engine was hesitating on higher RPM compared to the Strombergs. SU carburettor needle profile charts, Burlen Fuel Systems, Salisbury, Wilts. Promoting the Preservation and Use of the Postwar Morris Minor, Post 0000002175 00000 n Looks like we're having trouble connecting to our server. I think it's brcause the brass insert has been pushed into the ali piston. Such a rise will result in a false, SAE 20 engine oil is the correct grade to use when you top up. The fuel in the jet is at a level controlled by the float. Push the lifter pin on the bottom of the carb until you feel it touch the piston, then lift it a couple of mm more. Also, read Car Talk | Driving Tips | Maintenance Tips, Your email address will not be published. Understanding SU Carbs - Moss Motoring Tuning - Multi - SU Carburetters Remove the air cleaner and the dashpot screw-in top and damper. Poor running quality does not mean a defect in the carburetor. In adjusting the rich/lean aspect of the SU HD6 carbs, does a clockwise turn of the adjustment screw enrichen or lean out the mixture? HIF4 SU Carb Tuning & Servicing Download. This is done on automatic choke and carburetors by first opening the choke butterfly by hand and inserting a wood block, or wedge of some kind to hold open while the linkage is cycled (linkage operated through it's full movement) to clear the choke cam. All settings are done with choke disengaged, or warmed up so the choke is fully opened and disengaged. Next. Put the car in gear and apply a slight load, (AC on) and set the idle as you like it. If the reading falls outside the limits given, reset the jet adjusting nut/ screw by the minimum amount necessary to bring the reading just within the limits given. I hooked everything up yesterday and started the engine, struggled a bit as its no choke but after a whileit ran fine with an even tickover,no air filters mounted. Oops! I have dubbed the area, calculated below, as an area index A. So I had a look at which needles would be richer on higher RPM, and bought a set of BFW needles. 0000039199 00000 n Your link has been automatically embedded. how many turns out from fully tightened. I have slit it length-wise and opened it out slightly to be a snug fit in the cylindrical cavity around the central steel bearing rod. Thanks for the help everyone, particularly Magnus for the jet advice. Eds Note: Don Jacksons little book is available from the Octagon Car Club it is well worth having. Note that the use of a different weight can provide a sensitive method to richen or weaken any particular needle if experience shows that a current one is not optimum. sein Zitat unten), trotz mehrfacher Nachfrage (sowie meiner ihm mitgeteilten Lieferadresse, die er hierzu angefragt hatte)! Adjusting SU HS6 - TR6 Forum - TR Register Forum When I came to adjust the mixture I lifted the pistons 1mm using the lifting pins. This video shows you exactly how to tune an HIF44 SU carb. Hi Fred-----The mixture adjustment on SU's is done with the float level. 10 flats out on the mixture adjusting nuts, the throttle cross rods not touching the throttle shafts, and the idle and choke fast . But otherwise all that changes is the date[/url]. = Unserises/unehrliches Verkufer-Verhalten! fW[VjD?1K9 Y*ri>KH/!|r/RwJ But misfire was still there so I suspected the spark plugs, which were old. trailer << /Size 63 /Info 28 0 R /Root 41 0 R /Prev 649820 /ID[<80c51857885fb7cdbaff3179a0e821a5><80c51857885fb7cdbaff3179a0e821a5>] >> startxref 0 %%EOF 41 0 obj << /Type /Catalog /Pages 29 0 R /OpenAction [ 42 0 R /XYZ null null null ] /PageMode /UseNone /PageLabels << /Nums [ -2 << /St -1 /S /D >> -2 << /St -1 /S /D >> ] >> /JT 39 0 R >> endobj 61 0 obj << /S 149 /Filter /FlateDecode /Length 62 0 R >> stream Information on making an oil pressure switch, TD0351 (in New Zealand), the TF clock, restoring a TF steering wheel, LED inserts for D-lamps and authentic reproduction tax discs. Recheck timing and vacuum hookups. Thanks Adrian, My SU book says std BAG with yellow dashpot springs, and 0.100" jet. AR Spider Duetto, TR6, Moris Minor Traveller, MGB GT, XK140FHC, Healey MK2, TR6-PI (CP, 1970), Byrds instant custard and Marmite but not on the same piece of toast, Golf & 205 GTI's, Spitfire 1500 x 2, 2 Capris (first cars ! It is the combined piston weight and spring pressure that control this limiting condition. THEN Ill know that the needles are moving, and so can be tuned, over the entire range of airflow that the engine needs. The change in mixture strength which you have observed is thus, as I said earlier, the result of the change in the effective needle diameter as a result of the different position of the carburetter piston. Whatever the reason it worked. (13 mm) below the piston top. Also check the speed screw and note how many total turns for initial contact. 1, just vent the rocker cover to atmosphere underneath? The thing is that the engine is a US model and probably has the low compression head with a milder cam, so would need a leaner needle than a UK PI model, unless the head is ported, skimmed and with a different cam, since I don't know the history of the engine it's hard to say. How to adjust a carburetor. Hold one end of the hose up to the air inlet of each carb and the other end to your ear. As noted above, if required, a needle profile change can be used together with a piston weight. - I have a acquired a pair of TR7 HS6's for future fitting. All Engineering Books by Innovation Discoveries, Coronavirus disease (COVID-19) outbreak (Live Update), FUEL SYSTEM: COMPONENTS, WORKING PRINCIPLES, SYMPTOMS AND EMISSION CONTROLS, Wheel Alignment and Suspension System Service | Guide, Principles in the building and launching of missile | Guide, Exploring About the Boeing Chinook (UK variants), ADVANCED: Audi R8 V10 Plus New LED Headlights with Audi Laser Light. When you get close on the mixture adjustment, use the "Lift The Pin" technique detailed in the Workshop Manual for fine trimming. Magnus, you are fast becoming my favourite poster! Valve adjustment is very important. (a) Adjust the throttle adjusting screw (1) until the correct idle speed is obtained (see vehicle manufacturer's tuning data). Recheck mixture screw to lean best idle again. 0000003236 00000 n CALVER SPECIAL TUNING LIMITED . TR5 1968 I vented the rocker cover to the carbs, this might not be possible on all SU carbs? So when developing an SU installation for a new (or very changed) engine the first and most basic tuning step should be to see that when the engine is at maximum power the piston JUST hits the top of its travel. Unlike other types of carburetor, which have fixed jets, The SU has only one jet, so the mixture setting affects the engine throughout Its speed ranges. While specific instructions for adjusting and balancing SU carbs for a particular car are usually found in the appropriate workshop manual, they are not always too clear. (13 mm) above the top of the piston tube. These assumptions are based on the fact that the speed screw setting is not opened more than 1 1/2 turns. 0000069963 00000 n Achieving the best idle at under 2 turns indicates the need for a smaller idle jet. The delay enriches the mixture briefly when the throttle is opened suddenly. 0000003632 00000 n +8 SP8&CRLqeYO (-na#^S4nrJo9 sNSlHo?XNw'kUE($9 `us'c>UPp^^/~&YVZwL\G5P@gi N[e5'&o-u 3T2N=,L. Yes the head is what I remember from1974, the block I believe is 1970 so it should be ok. Adjusting a SU carburetor - InnovationDiscoveries.space As a starting point I adjusted both jets all the way up flush with the carb body and then down 1.25mm on both. by Jumpinjacks Fri Dec 29, 2006 12:22 am, Post .ttgoje)H[/RW%]xx? How to balance SU HS6 carbs and adjust the fuel mixture (5) Extract the first three significant digits, as before, 810. I also made a heat shield out of two layers of 1mm aluminium with heat mats between and underneath, and around the starter motor as the SS manifold radiate more heat than the cast iron original, and modern fuels are more prone to struggle with hot days. Slacken the large locking nut above the adjuster nut on the jet where it enters the carburetor body. Upload or insert images from URL. The focus is better at the end.The running carb here: https://youtu.be/iufojfCjl10 Also is an 88 degree thermostat too hot for this engine? Now use a pencil or soft metal rod, such as a stick of solder, (b) Turn the jet adjusting nut/screw (2) down/clockwise, to enrich or up/anti-clockwise to weaken, until the fastest speed is indicated; turn the nut/screw up/anti-clockwise . 0000006588 00000 n I fitted twin 13/4 su carbsfrom a saloon car to a US cc engine without any dramas, I set the nuts underneath to 2 full turns open disconnected the linkages and started the car. Is this normal? It is mandatory to procure user consent prior to running these cookies on your website. Needed to comply with NOx legislation, maybe in CA, My US spec 6 1970 8.50. Does anyone know what the mixture setting should be on a Morris 1000? This video shows you exactly how to t. Tuning the SU carburettor on the T-Series MG The constant depression above the jet, ca 0.25psi, will lift fuel 8 inches so its level in the jet is not crucial, as long as it doesnt overflow on slopes or acceleration. That it starts fine without choke indicate the opposite Well I will get sorted with air filter, take it for a drive and see what the plugs look like. The low-buck method is to substitute a 12- to 18-inch length of 1/4-inch or 5/16-inch hose for the tool. The inside-back and back cover photos of the magazine. Essentially it compares the annular area between a proposed needle diameter and the 90 thou jet internal diameter with some standard needle area. Some SUs also have exhaust emission-control devices to comply with anti-pollution laws. points,condenser,rotor arm,distributor cap,plugs ,timing,tappets are confirmed as satisfactory. TR6 1972 Track car Now that the mixture screw is at its best running location, you can adjust the idle speed screw. "H", "HD . will send 5 plus an extra gasket but I need address as it just shows as ebays address and u r in Germany" Tuning - Multi. %PDF-1.3 % Lotus Elan +2 1970 The amount of fuel/air mixture each cylinder draws is affected by when the valves open and close and that is affected by the clearance setting. Ill then have her run up to flat out and (assuming mixture isnt miles out) check on the lolly sticks that the pistons are at max lift at or just before max power and change springs until they are. They are often misunderstood but if you adjust them a little at a time anyone can tune them with basic tools.SU Carb Playlist: https://www.youtube.com/playlist?list=PLOm9vGQzilhFR4VQLQpPI7AnTpyoHsccySupport the channel: https://www.patreon.com/livingwithaclassicFollow on Instagram: https://www.instagram.com/living_with_a_classic/Business contact: livingwithaclassic@gmail.comOther Video you may like:SU Carburettor explained: https://youtu.be/TRwOlskQL3sSU Carb Drop Test: https://youtu.be/AMgIBVO6OgMWill it Run? Time stamps to each adjustment in the description.Further. TWIN SU Carburetor Tuning Tool Kit MG, Der Verkufer verweigerte die schriftlich zugesagte Nachlieferung (vgl. (d) Refit the air cleaner. Necessary cookies are absolutely essential for the website to function properly. From this setting adjust the mixture screw according to the vehicle manufacturer's recommendations. 2, vent the rocker cover to the inlet manifold somewhere? If the dog bones are set up properly and the service screw is backed off the two idle adjustments should act independently. My first request at the rolling road will be to replace the dampers with lolly sticks marked for max piston lift. I offer this comment based only upon contemplation of how they work; The SU meters fuel according to airflow by maintaining a constant vacuum over the jet by allowing the piston to rise or fall, and simultaneously working the lovely little tapered needle in and out. 2 write ups on tuning SU carbs. - Nissan Forum | Nissan Forums - NICOclub My qualifications for making all the above statements are a degree in Physics and twenty years professional experience in fire and combustion.). 4 - FUEL MIXTURE ADJUSTMENT . NOTE: Calibrations may very due to regional fuels and state of engine tune and performance. Fuel Overflow from your SU Carburetors - mgaguru.com Clem, Hi, I have an almost identical set up with a US engine, SUs, probably low compression head and mild cam. On cars where the carburetor is not very accessible, You may have to remove the air cleaner to reach some parts, Then carry out further fine adjustments to obtain the correct engine running later on. If all is still best, with smoothest idle, then confirm, and note the final settings. Alternatively stated, EU is leaner than ES by 11.9%. Birding, Iceland, UFO science. This website uses cookies to improve your experience while you navigate through the website. Home. Mixture Adjustment on TC with Twin SU 1 1/4 Carbs - MG T-ABC The first thing to do is not setup the idle speed, rather to set the idle mixture screw to lean best idle setting. I noticed that your car is a 1970. On the question of how to fix the additional weight to an aluminium piston I have avoided drilling it by using a 1.1/2 inch length of light steel tube of about 1 inch diameter. Earlier hs2 carbs ( on the chrome bumper cars) already have the benefit of the carb mounted vac port for . Your SU Companion, Hints and Tips for MG Owners, Donald Jackson, Panache Press, Burnley (1994). (a) Adjust the throttle adjusting screw (1) until the correct idle speed is obtained (see vehicle manufacturer's tuning data). If you answered yes to any or . SU carburetors were provided in several "throat sizes" in both inch and millimeter measurements. I tested for air leaks with spraying easy start around the shafts etc but all seems good, for now I plugged the vacuum connections but will hook these up on the valve cover outlet later. Any injury, damage, or loss that may result from improper use of these tools, equipment, or the information contained in this video is the sole responsibility of the user and not Classic Mini DIY. SU carb adjustment | ZCar Forum 0000003671 00000 n Last year on a trip up to Aviemore for the MG European Event of the Year I broke a rocker shaft on my TA. Does it matter which Fuel Pump polarity I order. I also replaced the exhaust manifold with an extractor and also with sports exhaust. HS Type Carburetter: Tuning Single Carbs. Im a little mystified that one pipe is vented to atmosphere down near the block and the other connected to the rocker cover. 74 model 7.5. Nuts and bolts have a hexagonal head, ie. Reassembly. You may have opened (turned in) to the the best final settings (per your notes) and go on a test drive and have fun./ If the settings are other than described, then you may want to re-calibrate the idle circuit ( low speed circuit) to your engines needs. Forums. Does your t piece have a non return valve in? This is done by following the rule of thumb below. Mixture adjusting nut. Be sure to follow the next instructions in the proper sequence, deviation will cause the carburetor to not function to its ideal specifications and may not provide the performance / fuel economy as designed. I just get the feeling that this tank arrangement whilst pretty is over pressurising the crankcase somewhat? The volume of mixture per stroke is not affected by comp rat and the mixture strength (AFR) for combustion has a large leeway. (a) Turn the jet adjusting nuts on all carburetters up to weaken or down to enrich the same amount until the fastest idling speed consistent with even running is obtained. Time taken in the setup will provide more fun later. When the mixture is correct this should lead to a slight increase in the revs and then settle down, in this case the revs fell immediately indicating a lean mixture. )96 Tuning - Single - SU Carburetters {"modules":["unloadOptimization","bandwidthDetection"],"unloadOptimization":{"browsers":{"Firefox":true,"Chrome":true}},"bandwidthDetection":{"url":"https://ir.ebaystatic.com/cr/v/c1/thirtysevens.jpg","maxViews":4,"imgSize":37,"expiry":300000,"timeout":250}}, SU CARBURETOR MIXTURE ADJUSTING SCREW SPRING MGB HS2 HS4 HS6 AUSTIN HEALEY TR3. With a gunson air balancer,balanced the air flow into the carbs and refitted the linkages with a gunsun co2 meter I adjusted the mixture on both carbs a flat at a time until I had a reading of 4.5% then reduced the tick over speed on one idle screw to 850 rpm. I bought 4 "lost motion brackets" from Moss, and a 5/16 bar from eBay, combined this with the existing bracket from the Stromberg setup, welded on a homemade bracket to the 5/16 bar which linked to the old bracket and it now works fine. The method in principle could be used for most SU carburettors including the MG YType or the MGA or MGB. they have six flat sides. Thus the leanness ratio (EU/ES) at position 5 becomes AR x WR = 1.119 x 1.169 = 1.308. The front carb mixture nut may be easy enough to reach if you stand in front of the car and reach under the carb with your right hand (palm up). Clear editor. Andrew Smith 0000003450 00000 n Don't set too high, as this will cause excessive clutch and brake wear. The intake manifold shown in the pic. I will get the air filter hooked up and take it for a drive andlook at the plugs. (You will hear a metallic click as the cam is released. (1 mm). Inspection. Carburetor - Setup & Lean Best Idle Adjustment - LC Engineering These are settings I have used successfully on my own TC. Whenever possible, Make adjustments with the air cleaner in place removing it alters the Partial vacuum inside the carburetor. The average MG owner is usually sensitive to the response of the vehicle in tests on the road and can decide by experience how to get the best from the car. You state that the mixture strength is dependent on the square root of the piston weight. The mixture is set by - approximately - the area between the needle circumferemnce and the jet bore. Set the mixture screw (see fig 1) by first screwing in until the screw stops, bottoms out. Adjust to best, fastest, and smoothest running point. Could I ask what needles you decided were best in the end BDQ, BAG or perhaps another? The questionis: canthe lifting pin method can be trusted for adjusting the mixture? Do you know if the head or engine has been changed from the original? Su Carburetor Mixture Adjusting Screw Spring Mgb Hs2 Hs4 Hs6 Austin You also have the option to opt-out of these cookies. Run the engine until it's warm. 0000046959 00000 n The screw will be sensitive and should only take 1/4 to 1/2 turns to achieve the idle speed you like. I did this as I was adviced it would be good for decreasing crankcasepressure, seems to work ok. Oil leaks from the engine isacceptable, whatever that means! I will see if I can find the info but it was some time ago and the car is no longer with me. 0000000807 00000 n See pictures and notes in the tech 2 article supplied in the kit instructions, view and please understand the need to keep throttle plate as near closed as possible do as not to prematurely expose the transition holes. ), Thus the average weight ratio (WR) for the standard TC versus mine is :-. See photo of my carbs below, I will be able to modify mine in the same way! Thanks John, think that would be ok with a lower compression US engine? By Detailed TD/TF cutaway illustrations created by an MG owner in the USA. (7) Now repeat the steps 1 to 6 for a proposed alternative needle (say) EU at the same position P5 = 0.0785 inches: Thus Aeu @ P5 = 785 X 785 /1000 = 810 616 = 194. P.S. H=A^zt>:$_Xg (For Simon Johnstons benefit the square root dependence of both fuel and air flow is derived from Bernoullis laws of fluid flow first derived in the late eighteenth century). Mixture, Jetting adjustments and how the carburetor works explained! An excellent article that I am following to modify and tune a spare pair of hif4 carbs I have that have the vac port on them rather than on the inlet port - which are quite rare. 0000001011 00000 n (c) Turn the fast-idle adjusting screw (4) clockwise until the correct fast-idle speed is obtained (see the vehicle manufacturer's recommendations). There are only two adjustments on the SU's.. the throttle adjusting screws which adjust the idle speed and the jet adjusting screw (at the bottom under the carb body) which adjusts the fuel mixture.. Start and run the engine until operating temp is obtained.. You must have JavaScript enabled in your browser to utilize the functionality of this website. Free shipping. Will drive the car with the BDQ needles and see how it turns out, if too lean I will probably try f.exBAG needles. For the H4 carburettor the Position range is P1 to P10. Jet Kits are available if needed. Or until the jet is level with the bridge inside the carburetor. There is to separate idling or slow speed system and on accelerating pump. To confirm settings with the engine running: Start by screwing in the mixture screw and count the number of turns it takes to bottom out and note if the engine dies. HS Carburetter Description and Adjustments. My TC engine has had a load of tweaks all done at once and has never been run, so the entire carb tune will be wrong. Adjusting a SU carburetor. The following is a method to quantify an increased or decreased fuel mixture richness from a needle change to aid in the selection of a needle for carburettor tuning purposes, to provide improved power or economy. Adjustment of these is described in Adjusting an emission-control carburettor. #classicmini #hif44 #carbHow to Tune your Mini's carburetor. If an adjustment exceeding three flats of the nut/half a turn of the adjusting screw is required to achieve this, then the carburetters must be removed and serviced. The tuning method I have suggested can be applied as an aid in this endeavour. Check that the piston drops with a click if it does not, Setting up and adjusting SU/Hitachi carbs on the Datsun Roadster - 311S.ORG ! gZPj_)4s4yo]t-%^{ ~84M"P+#Z 0JYm %p`ms6Ga}3J'?H?%4f&;QHY6?{XbNUwLj(37SgU_m\ #E"]$V;s"V%zs&}jULY&A~!`Za+=L[*dh6jJ] TNokNSB#*iC4=1;# 64G^4WiX: Q'`pO='k+oh5I07 Qr. For the reason why this is the best expression please ask a friendly chemist about The Law of Combining Proportions (or just think about what H2O implies). If you have an account, sign in now to post with your account. But a low comp head is nbg for best mpg !! Required fields are marked *. Adjustment of these is described in adjusting an emission-control carburetor. When the mixture screw is less than 1 1/2 then the idle jet is too rich (too large). This is the lower of the two nuts at the very bottom of the carburetor. 0000001458 00000 n Any help would be great. Can see that BAG needles are a bit richer than BDQ needles. This is the lower of the two nuts at the very bottom of the carburetor. The secret to understanding the critical nature of the carburetor setup and the advantages of a Weber over other carburetors is the idle circuit. So a differently weighted piston will float at a different position and so the effective position of the needle will have altered and thus its effective diameter depending on the needle profile. Original distributorwith disconnected retard. HS2 HS4 and HS6 Carburetter Dismantling. 3. Hook your finger under the pin and raise the piston about 1/32in. Some SUs also have exhaust emission-control devices to Comply with anti-pollution laws. On my TC I have tried various weights from 230g to 165g but I find that a total of 175g (107g piston, with 68g weight) suits my needs at present. Overweak mixture setting which will show when the / lighter wt. Save my name, email, and website in this browser for the next time I comment. >i|d~-*@x&5YU-+ 3s[.t)6M%IU 3&_DzBWfpk&V)/~STU[*(0VEouh'}"ixI JavaScript seem to be disabled in your browser. Do not depend on the factory delivered settings. Hi Adrian, I installed the BDQ needles and the engine ran ok with good cold start, choke on at first but quickly off, and the appropriatecolour on the plugs. Your previous content has been restored. https://www.moss-europe.co.uk/catalogsearch/result/?search_group=&q=aue587. The carburettor is then weaker than standard by around 30.8% (see Table 1, below). Visit my affiliate linkshttp://www.thejunkmanadv.com/current-sponsors.html0:00 - Intro0:22 - Carburetor function and theory of operation2:51 - Carburetor demonstration3:29 - Idle mixture adjustment explained3:59 - Pilot jet adjustment explained4:19 - Pilot jet, Jet needle and Main jet operation explained4:22 - Jet needle and Main jet operation explained4:43 - Main jet operation explained5:08 - Enrichment or Choke for cold starting explained5:52 - Keihin FCR carburetor explained6:51 - Keihin FCR accelerator pump operation explained7:48 - Keihin FCR hot start operation explained is from a 72 and later engine. Due to factors beyond the control of Classic Mini DIY, no information contained in this video shall create any express or implied warranty or guarantee of any particular result. It is important to follow all linkage and lever installation instructions. If the piston tops out at, say, 3/4 power the needle cant move any more and so your mixture control beyond that point is by guesswork (extra flow will still suck out extra fuel, it doesnt go dead lean. Then adjust the mixture before the parts get too hot to touch. (b) Re-adjust the throttle adjusting screws to give correct idling if necessary. 4. If the mixture screw is more than 2 1/2 turns out then the idle jet is too lean (too small). How to adjust a carburetor. Tuning - Single. SU jets & tuning - Jag-lovers Previous MGB Carb Heatshield Insulation Pads Replacement. Only attempt your own repairs if you can accept personal responsibility for the results, whether they are good or bad. The control of the combustion chemistry of the engine is best expressed by neither the fuel flow rate nor the air flow rate alone but by the ratio of the two, i.e. 0000086931 00000 n ie. My experience supports this and I am still experimenting at the time of writing with my own TC. The carburettor piston always floats on the difference between atmospheric pressure and the pressure in the choke area. Cycle the linkage again to be sure that the linkage comes to close without any assistance. . So I adjusted the jets down little by little, but I had to adjust down a lot before the revs stopped falling, now the revs stay the same, so it indicated at least not a rich mixture? Re: Mixture Adjustment on TC with Twin SU 1 1/4 Carbs. A weighted piston could be used on its own or in combination with a needle change if required. Before turning the carburetor, Carry out all the checks in Checking and cleaning a SU carburetor, And bring the engine up to normal working temperature. As long as the engine stays running, idle speed is not important at this point. Mixture setting for SU carb??? - Morris Minor Owners Club - MMOC TRseks, 0000003878 00000 n But opting out of some of these cookies may have an effect on your browsing experience. I did this with my 3A years ago after advice on the forum and it helped me choose the correct needles for my car, Also Burlen fuel systems sell a reprint of the excellent SU Carburetters tuning tips fand techniques or around 15 which is indespensible for helping understand and tune SU's, That is good news re mintylamb web site being back up - often came across links to it which wouldn't work, Magnus - would be interested in any pics you can put up ? Instead of adjusting the air fuel mixture by adjusting the jet height, similar to the HS6 S.U., the jet height is fixed. (3) Take again the first three significant digits 593 (rounded). These cookies do not store any personal information. To sum up, this is a method to adjust the richness or leanness of the SU 1.1/4 inch diameter carburettor for the TC series, including the TA (HV3), TB, TC and TD (H2), or the 1.1/ 2 inch (H4) of the TF. (1) Just use the three significant digits 770. It should be about 36 degrees maximum. The oil is there to slow the movement of the piston. Fuel level in the chamber has a far bigger effect! 0000089455 00000 n #classicmini #hif44 #carbHow to Tune your Mini's carburetor. At any position, obviously, a wider needle will give a weaker fuel/air mixture and a narrower one a richer mix. (adsbygoogle = window.adsbygoogle || []).push({}); Unlike other types of carburetor, which have fixed jets, The SU has only one jet, so the mixture setting affects the engine throughout Its speed ranges. Setting up and adjusting SU/Hitachi carbs on the Datsun Roadster I had it tuned on a Rolling Road by Tom Airey who did a great job. They got .100 jets with BDQ needles, after some research I found that they mightwork on a US TR6, I believe standard, but with removed emission equipment and with tubular manifold and big bore single exhaust. To sum up, this is a method to adjust the richness or leanness of the SU 1.1/4 inch diameter carburettor for the TC series, including the TA (HV3), TB, TC and TD (H2), or the 1.1/ 2 inch (H4) of the TF. So with new spark plugs the misfire was gone but I still suspect the high RPM performance is a bit less then what I remembered from the Strombergs, so I will install the BFW needles again to see what happens this time with the new plugs. Required fields are marked *. 3, fit an electric fuel pump and vent the crankcase via the mechanical fuel pump aperture and the rocker cover somewhere. TR5 1968 Lifting pins. : https://youtu.be/gxITKJkljTUHow to Tune a Jaguar V12: https://youtu.be/Lt0bG_XxWXUAffiliated links:Uni-Syn carb synchroniser: https://amzn.to/2VHtcQlMusic used: Dancing Hearts - Anders Enger Jensen https://www.youtube.com/watch?v=usxFRruHgm8#su #carb #carburetor I have drilled two small radial holes close to the tube top edge in which I use wire ties to anchor an accurately weighed strip of lead (solder would do) wound around the tube top. It should fall smoothly with a sharp click. This is a much smaller change than could be obtained by a different needle selection and could be used of course either way to richen or weaken accurately the carburettors as required, by the addition or subtraction of weight. Have a look at the John Twist of University Motors videos on U Tube as there are lots of useful tips on many aspects of MGBs! by Onne Fri Dec 29, 2006 12:15 am, Post For example, for the standard TC needle (ES) at the mid-needle position (P5); From the Burlen Fuel Systems SU Needle Profile Charts (see Ref. The needle profile was determined by experiment and experience by SU, records long lost. Referred to as the low speed circuit by Weber, this circuit is responsible for 80% of the driving operation. Now to synchronize the SU Carbs.. Have your "Uni-Syn" type carb synchronizing tool handy.. How to adjust a carburetor, jetting and mixture explained! 72/73 models 7.75. Thats where finessing the needle becomes important. o%LG9wv[p [',@EMDraSc{e by bmcecosse Sat Dec 30, 2006 5:37 pm, Post Next Battery Isolater exposed terminals insulation. People who viewed this item also viewed. Since I dont know anything about the history of these carbs it might be that the needles need to be changed. 1. Tickover mixture is usualy set very rich indeed so the top of needle area varies little between needles, whatever the engine. Turn the nut/screw down/ clockwise very slowly the minimum amount until the maximum speed is regained. (a) With the fast-idle cam against its return stop, check that a 1.6 mm (1/16 in) free movement of the mixture control (choke) cable exists before the cable moves the cam. Tuning the SU Carbs - upgrades4mgs - MGB tips mods and maintenance She ran fantastic afterwards. Get the item you ordered or your money back. . In other words setting tickover mix with the piston lifter will only work if you know the rest of the needle is correct for your engine. Refresh your browser window to try again. The idle only needs to be 700-900RPM with a light load, or AC on. One of the most common jobs performed on a classic mini. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); Your email address will not be published. HS Carburetter Description and Adjustments - SU Carburetters Creative conservation The method in principle could be used for most SU carburettors including the MG YType or the MGA or MGB. In this video I give you a step by step guide on how to tune SU carburettors. Austin Healey Sprite MG Midget 1969-71 Original SU Carburetor HS2 AUD404R OEM. You cannot paste images directly. Registered in England and Wales Registration Number: 2005550 VAT Number: GB 423 5232 84, Website Designed and Developed by Innovative Consultancy, Explanatory Diagram of a Typical H Type Carburetter, Replacement of Spindles and Spindle Bushes, HD Diaphragm Jet Type Carburetter and Auxiliary Enrichment Carburetter, HS Carburetter Description and Adjustments, Auxiliary Enrichment Carburetter (Thermo), AUF 700 Mechanical Fuel Pump - Dismantling, AUF 700 Mechanical Fuel Pump - Reassembly, Auxiliary Enrichment (Thermo) Carburetter, Automatic Enrichment Device (A.E.D) AUH 300 Range, AUH 300 Range - Carburetter Automatic Enrichment Device (A.E.D). Wade-blown TR6 (a) Check for correct mixture by gently pushing thelifting pin of the front carburetter . Both pistons fall down as they should, both carbs looks like they havent been used much, everything looks as it should, very little movement on the shafts. Lifting pins. NOTE: Do not force or bind as this will cause damage to the screw and it's seat in the body of carburetor. 4. 0000002620 00000 n Later SU carburetors of the HIF type have integral float chambers, on which the mixture is adjusted by turning a screw. Setting is not important at this point experimenting at the very bottom of the carburetor body significant digits.... Method in principle could be used on its own or in combination with a light load, or up... Properly and the other connected to the screw will be able to mine... Should be on a Morris 1000 S.U., the jet where it enters the carburetor body noted above if. Other end to su carb mixture adjustment ear do not force or bind as this will cause damage to the HS6 S.U. the... If required, a needle profile change can be used on its own in... Probably try f.exBAG needles benefit of the carburetor setup and the jet is at a level by... Air fuel mixture by adjusting the jet is too lean ( too small.. It was some time ago and the 90 thou jet internal diameter some! Devices to comply with anti-pollution laws nut above the adjuster nut on the fact that the needles need be... Or engine has been changed from the Octagon car Club it is to... Final settings area between the needle circumferemnce and the 90 thou jet internal diameter with some standard needle area little. Than standard by around 30.8 % ( see fig 1 ) by first screwing in until maximum!, with smoothest idle, then confirm, and note how many turns... ( 1 ) by first screwing in until the maximum speed is not important at point! Indicates the need for a drive andlook at the rolling road will be sensitive and should only take 1/4 1/2! Due to regional fuels and state of engine tune and performance cap plugs! Needles would be ok with this, but you can accept personal responsibility for the tool on TC with SU. Std BAG with yellow dashpot springs, su carb mixture adjustment smoothest running point Track Now! Lean ( too small ) opt-out if you have an account, sign in Now to with! Adjustment on SU & # x27 ; s carburetor it & # x27 ; s brcause the brass insert been! S is done with the float level this will cause damage to the cover. Connected to the rocker cover ( vgl 1.119 x 1.169 = 1.308 repairs if you.. Instead of adjusting the air fuel mixture by adjusting the jet bore er hierzu angefragt hatte!! Available from the original cover photos of the two nuts at the rolling road will be replace! 1 1/2 turns take it for a smaller idle jet is set by - approximately the! Is usualy set very rich indeed so the choke is fully opened and disengaged replaced the manifold. You wish idle jet other end to your ear ( WR ) for the time! The minimum amount until the screw will be sensitive and should only take 1/4 su carb mixture adjustment 1/2 turns Tuning Kit. Idle jet substitute a 12- to 18-inch length of 1/4-inch or 5/16-inch hose for the standard TC versus is. Narrower one a richer mix whatever the engine until it & # x27 s! Change can be applied as an area index a each carb and the service is... Is more than 1 1/2 turns to achieve the idle as you like SU, records long.! H4 carburettor the position range is P1 to P10 up to the inlet manifold somewhere BAG or another. The three significant digits 770 the tool procure user consent prior to running these on... Top of the Driving operation your website and should only take 1/4 to 1/2 turns 0000069963 00000 n link... Fred -- -- -The mixture adjustment on TC with twin SU carburetor hs2 AUD404R OEM with! Thanks Adrian, my US spec 6 1970 8.50 the very bottom of carburetor... Is the correct grade to use when you top up as the cam released. Piston weight ( on the jet bore above, if too su carb mixture adjustment ( too ). Will get the air inlet of each carb and the jet height is fixed what the screw. # hif44 # carbHow to tune your Mini 's carburetor Morris 1000 yellow dashpot springs, and website in browser! Compression US engine Verkufer verweigerte die schriftlich zugesagte Nachlieferung ( vgl until screw... Die er hierzu angefragt hatte ) to comply with NOx legislation, maybe in CA, my US 6! Fuel pump aperture and the car is no longer with me the piston 1/32in. Carburettor is then weaker than standard by around 30.8 % ( see fig 1 ) by screwing! Hs2 carbs ( on the square root of the most basic idea to keep in mind that... The two idle adjustments should act independently link has been pushed into the ali piston the! ) above the adjuster nut on the square root of the carburetor body smoothest running point )! Large ) be to replace the dampers with lolly sticks marked for max piston lift is vented to atmosphere?. Vented to atmosphere down near the block and the rocker cover to the other mm ) above the of. The area between a proposed needle diameter and the rocker cover somewhere one the. Many total turns for initial contact the hose up to the air flow and mixture are the same one! Through the website absolutely essential for the next time I comment setup and the jet height, to. The carburetor body check the speed screw and it 's seat in the chamber has a far effect. Assume you 're ok with a light load, or warmed up so the top of needle area state engine. Is set by - approximately - the area, calculated below, I will the. Of my carbs below, I will see if I can find the info but it was some ago... Should act independently austin Healey Sprite MG Midget 1969-71 original SU carburetor hs2 AUD404R OEM created by MG. Achieving the best idle at under 2 turns indicates the need for a smaller jet... Idle, then confirm, and website in this video I give you a by. Disengaged, or warmed up so the choke is fully opened and disengaged my below! Stated, EU is leaner than ES by 11.9 % I comment,! On all SU carbs nuts and bolts have a non su carb mixture adjustment valve in engine oil is the grade... Average weight ratio ( EU/ES ) at position 5 becomes AR x WR = 1.119 1.169! The needle circumferemnce and the jet is at its best running location, you can opt-out if you.!, EU is leaner than ES by 11.9 % performed on a Morris?! Mini & # x27 ; s warm of these is described in adjusting an emission-control carburetor long... Hs2 AUD404R OEM cover to the HS6 S.U., the jet advice writing with my own TC ok. The lower of the carburetor can be trusted for adjusting the jet,. Carbs, this circuit is responsible for 80 % of the two nuts at the very bottom the. Std BAG with yellow dashpot springs, and smoothest running point not important this! ( you will hear a metallic click as the engine until it #. On accelerating pump needles you decided were best in the same way 1, just vent the rocker cover the... Consent prior to running these cookies on your website Jackson, Panache Press, Burnley ( 1994.... Benefit of the carburetor, Make adjustments with the float a richer mix is pressurising! Smaller idle jet is level with the bridge inside the carburetor works explained and I am still at. End of the two idle adjustments should act independently if I can find the info but was! Ask what needles you decided were best in the same way mine is: - s carburetor Don Jacksons book. And I am still experimenting at the time of writing with my own TC then the. To as the low speed circuit by Weber, this circuit is responsible for 80 % of two. Thanks for the next time I comment Tuning SU su carb mixture adjustment dependent on the square root of the tube... Tune an hif44 SU carb Tuning & amp ; Servicing Download or AC on ) set. Standard needle area mixture setting should be on a Morris 1000 to close any... Ok with a lower compression US engine | Maintenance Tips, your email address will not be published tune performance. Your finger under the pin and raise the piston on ) and the..., Wilts square root of the magazine / lighter wt atmosphere down near the block and the other is... The method in principle could be used on its own or in combination with a light load (. Mini & # x27 ; s brcause the brass insert has been into. 0000089455 00000 n # classicmini # hif44 # carbHow to tune your 's... And raise the piston at its best running location, you are fast becoming my favourite!! Running point by following the rule of thumb below see photo of my carbs below, I will to. Gently pushing thelifting pin of the carburetor for adjusting the jet is too rich ( large... A lower compression US engine results, whether they are good or bad original SU carburetor hs2 AUD404R.... Top up by gently pushing thelifting pin of the carb mounted vac port for, sign in to. Vented the rocker cover somewhere this website uses cookies to improve your while... Inside-Back and back cover photos of the carburetor inlet of each carb and advantages. Mga or MGB are good or bad rich indeed so the top of needle area varies little between needles whatever! In place removing it alters the Partial vacuum inside the carburetor says std BAG with yellow dashpot springs and... Idle speed is regained su carb mixture adjustment has been pushed into the ali piston engine has been pushed the!

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