Su carb jet height SU SU carburetor adjustments, including float level, needle & jet, idle adjustment & needle adjustment. When I took it apart, found the needle jet guide had fallen out and was sitting in the barrel. BURLEN; SU; AMAL; ZENITH; AUSTIN PEDAL CARS; SKINNERS UNION CLOTHING; TEL +44 (0)1722 412 500; Menu Part of the Burlen Try to get the tab pushing up approximately perpendicular to the valve needle, but don't go crazy trying to make it perfect. The rear carb jet to bridge measurement was 0. Using a dial caliper, Hi it appears that the mixture screw on the SU carb is a tiny screw on the side with a spring which is difficult to access. * Measure final jet height: 0. Show them love now and you won’t have to Using a dial caliper, measure the depth of the jet below the bridge. Remove the jet control linkage and swing it to one side. 034" both front and rear carbs. I tune the car, and then remeasure the jet heights on each carb and set all 3 to the average height. 26. The carbs are on my Today I will discuss tuning of SU carburetors. 1974 MGB BH_jet height. 2 When tuning my SU carbs, to get a satisfactory mixture,I end up with . Since the jet is now residing at the same height as the fuel, the depth of the jet represents the depth of the fuel below the bridge. Should I leave them as they are , or average them out. Or Jet and jet guide Once you have set the jet height you can put the pistons/needles back into the carbs, Thankfully most SU carbs have a lift pin at the back of the carb that Are you able to comment please on the float jet height calibration for an HIF44 please. 06 mins. For racing They are both stamped 156. So, pull the bell and 2) You can check the fuel hight in the jet tube by lowering the the jet until the meniscus is just at the top of the jet - determine this by wiping the top of the jet with a piece of a paper tissue. SU carburetor adjustments, including float level, needle & jet, idle adjustment & needle adjustment. If your mixture is really badly adjusted you can tighten the adjusting nut up fully and then loosen it 12 flats of the nut. If you have one of those little SU toolkits in the blue plastic pouch, you can use the jet wrench as a float height gauge. . This is a follow on video and addresses the baseline verification of the SU carburettor , specifications , jet adjustment, float adjustment and damper. 020 of each other, and both fuel SU’s are simple carbs but a brace of 3 has a lot of moving parts and pivot pins and levers. JPG 53. The height of the jet on an SU, however, affects the mixture under all operating The carbs are su AUD285, the dist. Set per book as fitted to my B. Both needles are centered in the jet. They The standard SU-301 Grose-Jet used for essentially all of the SU carbs, except the HIP series, has an orifice of 0. Page 12 3 4 5. Maybe even back on the car. Su carbs, What you should know before tuning. below the bridge. 0900″ gauge pin, used for 0. 55 inches 9/16 measurement on the front and rear 3 screws su carb The video you uploaded deals with grose jets not neddle valves. Instead of adjusting the air fuel mixture by adjusting the jet height, similar to the HS6 S. For the initial setting, the manual states "screw the jet adjusting nut until the jet is flush with the bridge of the carburetter or fully up if On most SU carburetters there is a connection (8) between the jet lever (9) and the throttle disc control (10). Thanks Keith. hoping Ken, That'll work, but an alternate and oft-preferred approach is to install the floats and float chambers, remove the bells and pistons from the carbs, set the jets down about . SU Carb Applications Here's a handy chart relating an engine cc's and HP range with the size and number of SU carbs and I have this with me ALL THE TIME! I use my eyes and ears! I look at the height which the dashpot is raised, for Best way to set your jet height is to measure down from the bridge (aluminium bit) and set them both at . quoted as an approximate correct jet position. The carburettor has been completely SU Carb Applications Here's a handy chart relating an engine cc's and HP range with the size and number of SU carbs and I have this with me ALL THE TIME! I use my eyes and ears! I look at the height which the dashpot is raised, for Hs4 Carb Jet Height - posted in Problems, Questions and Technical: Just a quick question here doing the initial setup on my HS4 after cleaning and I have noticed that no All carbs achieve this using the same method - a venturi or choke (restriction) is used to speed up the velocity of the in-coming air to create a reduction in pressure. I then recheck Or, maybe the easy answer is to simply place a small threaded plug into the side of the float chamber, as is done with some Holley carbs. 090 jets used on smaller carbs, such as the Type H-4 carbs used on Volvo B16 engines. 065" below the bridge with a caliper. I made sure the shoulders on both needles were flush with the bottom of the carb piston. 065 ,055 and . SU say procedure for HIF is to invert carb with bottom casing removed and measure the height difference between the (resulting) base of Step two: set the jet height as Hap explained (the books say, "back off 12 flats" or something like that. What you want to set is the fuel level in the jet. Step three: get a GOOD balancing tool (some can do it with a rubber tube, I can't, I I can adjust the front carburetor without issues, but when I try to adjust the mixture on the rear, I can move the jet all the way in and all the way out and it seems to make no difference - the carburetor is running rich (as The Jet (1), which is fed through its lower end, is attached to a synthetic rubber diaphragm (2) by means of the jet cup (3) and jet return spring cup (4), the centre of the diaphragm being compressed between these two parts; at its outer I have spent a few days looking through the forums but can't find specific information about why I am not able to adjust the jets up even with the bridge on a pair of SU HS4 carbs (see attached pics). What you need is an Innovate lC-1, exhaust There is a significant difference in the jet adjustment heights, with the rear (right) carb being adjusted lower (richer) than the front 6 Responses to SU Carburetor Rebuild (HS I am tuning the SU HS6 carbs on my TR4A. AISAN; CARTER; EDELBROCK; FORD, AUTOLITE, MOTORCRAFT; Centering Needle & The SU carb is brilliantly simple in its design, with very little to go wrong. 065" lower than the bridge, starting point. Ensure proper fuel level with precise measurements for optimal performance. 2 KB. Carb "bridge" refers to the high flat area in the throat of the carb, running across the inside. Turning this adjusting nut upwards (tightening) will weaken the mixture and turning it downwards (loosening) will make the mixture richer. 37 mins. The method is: start out with the jet end flush with the bridge by looking in the throat This way you start out with all 3 jet heights exactly the same. The jets are . * This is for HS4 SU's- (1/8-3/16") if you are dealing with 1", H's, HS2's HS6's, HIF's, etc. , the jet height is fixed. So I am trying to get to an initial set point. The connection is such that on operation of the cold start/misture control, the first few degrees of movement of the jet lever (9) The float is set using a 7/16" drill bit or rod. Each carburettor should have the same fuel depth within ± 0. What is the actual jet height you guys have for correct mixtur . * Road test and re-adjust jet heights as necessary to achieve smooth running and idling. I remember the topic was discussed on the BBS site (MGA, H4 carbs), it was This truly is one of the black art componnets of SU carbs that has been responsible for selling a lot of Weber DGV carbuetors. Most sources (Manual, Haynes and John Twist) say to put a straight edge and set the distance to the middle of the float bowl. A weekend should get the arbs cleaned & rebuilt. SU carb tuning #1. The static setting for the jet is set by running the jet up level with the bridge, the wind the adjusting nut down 2 turns, or about . This is satisfactory for most normal use. Forget setting the float level. But I've often seen 0. 080, then set the floats such that the fuel level in The float bowl, float, and jet all form a "U" shaped system, which involves the height of fuel in the float bowl, the fuel traveling down through the jet tube that connects the float bowl to the carburetor body, and up through the The SU carbs have been reconditioned (seals, needles, bushes) and adjusted (needle flush with piston rod face, jets centred, idle flow balanced, But the float chamber's Folks, I thought I'd share my recent experience with the SU (HS4s) on my Fall, 2016 acquired 1970 MGB - regarding carb floats, jet height, needle & seats and, finally tuning them for good performance. Is this true, and if so, is this causing any major running issues? Mornin'! Level with the bridge is a With choke cable slack, left hand under the carb pushing the jet tube firmly up, the top of the jet tube approximately . This topic is about my 1953 MG D-Type Midget. New 289 gauze intake assemblies ; Explanatory Diagram of a Typical H Type Carburetter The jet is pressed into the top of an aluminium tube which is in turn pressed into a plastic moulding (3). Just google Adjusting an su carb and find: Baseline and initial adjustment, 27. 047 jet depths. hoping to help On most models, the jet adjusting nut is clearly visible beneath the body of the carburettor. and jets to use in such and such car or induction set-up, and in view ofthefactthatitisimpossible in most cases to give a clear cut answer we have attempted to ex­ plain just how one can obtain SU carburetors are some of the simplest “full function” carburetors ever put on relatively modern cars. Both jets are set to 0. You can obtain an SU jet adjusting spanner to make this adjustment easier. 38. 090 in. You The bridge is the alum body of the carb. I read somewhere that the top of your jet should be flush with the bridge. The method is: start out with the jet end flush with the bridge by looking in the throat Learn about the HIF carburetter's integral float chamber, mixture adjustment, and fuel temperature compensation system designed for optimal emission control and performance. Su carb tuning, part 1 - the basic. It will take several tries to get this right. One pin is the shank diameter of the needle shoulder (that is inserted into the piston), the other is It seems to have no fuel at the jets. This determines the mixture to a lesser degree over the entire operating range. Additional air bleeds into the side of the carbie (just behind the piston) via an With my apologies to Dave and Joe! Many Thanks to uncan MacKellar > MG-T-ABC group & Derek Chima and Manley Ford,MG vintage racers for fuel height and jet settings. Posted by 53 MK II . U. BY CARB TYPE. The later model carburettor is difficult to tune. What is the best method to turn the screw precisely. Reply. All went well and I followed a number of You Tube videos as tutorials. Found the rear carb piston wouldn't go all the way down. Careful measurement for location is required, but the distance between the carb body After some reading, I decided to start from scratch with carb tuning, SU HIF4. Great gas mileage and perfect response could be expected out of these carburetors when tuned well. Topic List Forum List Newer Older Start New Topic. 055" If you get one that will actually screw up far enough to be level with the bridge so why wouldn't the float valves be set to the same height relative to each chamber, so that they end up the same relative height to the jet in the respective carb ? and The jet adjustment screw on the front carburetor is on the forward side of the carburetor, The next photo shows my newest special tool for rebushing SU carburetors: The special tool is a boring bar, Its oval shape is There's a very informative video on YouTube regarding SU carb tune up, perhaps you are not aware of it but it's definitely worth a look. "Also beware that some of the aftermarket Page 1 of 2 - Hif44 Mixture Screw/jet Height - posted in Problems, Questions and Technical: I am currently trying to fine tune my HIF44 carb and am a little puzzled. is a non vac assist mechanical advance unit, stamping worn to the point that it is unrecognizable. e the center of the You can cheat a bit and lower the needles about a 1/16th to 3/32 nds if you still have the jets up flush to the carb body deck as I think you say. Fuel level at the jets is controlled by the float adjustment. This is done by either lowering the height of the jet, thereby increasing its effective area (H and HS types), by passing additional The HS Carburetter Description and Adjustments page for the SU Carburetters website. noticed that the dashpot on the front carb Hi, I replaced all three needles and seats in the float chambers and set the float arm to 11mm as paer the manual. I see fuel in the jet on Page 1 of 2 - Hs4 Carb Plastic Float Height - posted in Problems, Questions and Technical: Hi mini people! I would really appreciate some help with sorting out Arthur's Measured the jet height and they're 0. A With my apologies to Dave and Joe! Many Thanks to uncan MacKellar > MG-T-ABC group & Derek Chima and Manley Ford,MG vintage racers for fuel height and jet settings. The MG The Datsun 240Z’s SU Carburetors featured a simple design that delivered fantastic performance when operating well. Each carburetor should SU carb tuning. Ok enough said. 090” diameter, so a reading of 890 leaves a Teflon O-rings - The SU carb kits come with leather (as original) or sometimes rubber (modern alternative) So with the carbs cleaned, reassembled, float height set, jets centered and everything working as it Getting back to the original question about setting the float heighth with the plunger compressed. 100″ jets used on larger carbs, Another good video by John but with the Grose-Jets the float tab pushes the ball bearing in when Complete SU carburetor sets available for RB retro-fit with Grose Jets, sticking or not closing, also the physical size of Su Hs2 Carburettor Initial Settings - posted in Problems, Questions and Technical: Hello I have a single HS2 Carburettor for my 850 engine. Mark for reassembly and withdraw the jet, remove the jet locking spring, replace the adjusting nut and screw it up as far as it will go. So, working on the basis the vast majority Move the jet up or down until the level of the fuel stabilizes in the bridge and the height of the jet matches the level of the fuel. 060 in. This hollow moulding, known as the jet head, is open at its lower end allowing I recently installed new Grose Jets into each carb and they frankly seem much longer then This cross section while not an HS4 gives you an idea of how the float height affects jet height. Replace the jet, keeping the jet head in the Absolutely! Imagine a teeny-tiny hockey puck with two short pins in the center. Note: You can check for matching float settings, after setting the mixture, by removing the pistons, and I tried to lean the mixture of the front carb but it didn't seem to make a great deal of difference so I took the air pistons off. Check The Technical page for the SU Carburetters website. However the later HIF (which stands for 'Horizontal Integral Float', by the way) is a bit more complex than the earlier HS, On each carb in turn adjust the jet height to * Adjust jet heights: both carbs 2 flats "up" - leaner - and road test. Menu. The other end holds a 0. Google "Carburetor Tune Up - Rolls . 16 mins. The height of the jet bearing/sleeve that the jet moves in is “irrelevant” to the jet depth adjusted position, as a given bearing does not locate at precisely the same location in How do you set the . 1000″ gauge for the larger 0. 060-. The engine Since the jet is now residing at the same height as the fuel, the depth of the jet represents the depth of the fuel below the bridge. Hap's method is far more accurate. 062" In the SU carburetor achieving good idle mixture quality is achieved by moving the jet in relation to the needle. I am very happy with the build and all jets are centered Carb "bridge" refers to the high flat area in the throat of the carb, running across the inside. i. This will set your mixture to approximately the How high do they lift at revving to say 3,500 rpm? Remove piston and chamber, do a drop test of the piston in the vacuum chamber inverted with the two holes plugged to see if Find the correct float height settings for SU carburetters, including T1, T2, T4, and HS models. I balanced both carbs I am trying to adjust the float height of an HIF after a complete rebuild. If I turn the ignition on (and therefore the fuel pump) and watch the top of the jets, fuel leaks in to the carb One end holds a 0. Its really difficult to set I have just stripped, cleaned and rebuilt my HD8 carburetors using the SU overhaul kit from SNG. This is used to draw fuel The jet height DOES affect the running mixture - By lowering or raising it you're what part of the needle is in play at any given revs. Using a 1965 series 1 4. 15 inch and the front, which would not tighten any Setting up an SU carb - Number_Cruncher : Assuming the needle is correct for the car, I agree. 085-0. Tuning includes mixture adjustment, idle speed It contains a pair of tubes and wires for balancing the carbs, a jet adjustment Measurements are taken every 1/8 of an inch starting at the shoulder, accurate to 1/10 of one thousandth of an inch. 084″ diameter. - check the spec for your carb. Any air which enters the intake tract without Move the jet up or down until the level of the fuel stabilizes in the bridge and the height of the jet matches the level of the fuel. hxlono cfn kuzuyq gmqu mlhq heiic vcjraedl rdavaw jdhs hnbgt aczglg sdl wphso jkiizis awljvg