Difference between hs2 and hs4 carb. - check the sp...

Difference between hs2 and hs4 carb. - check the spec for your carb. The obvious advantage of a single carb is much easier tuning. These are wonderfully simple designs using a variable main jet/venturi principle. The two steps to adjustment are to ensure that multiple carb setups have proper linkage balance between carbs, then to set the high-speed idle screws that touch the cams. HS2 mounting bolts are aligned vertically with the center-line of the carb. 2 Ball bearing suction chambers (early type). I have a feeling that H2 and HS2 are vertical whilst the offset one may be HS4?? (and not a MM 1098). (´74-´76 fixed jets, ´76 onwards Waxstat jets) 1000cc engines: single HS2 or HS4. Some commonly used carbs on specific engines/cars: 850cc engines pre 1974 single HS2 carb. Is it an HS 2, and HS4, or It is time to rebuild the carburetors, and I realized they are H4 not HS4. The Datsun Z cars also used SU carbs built by Hitachi. Meanwhile, professional rebuilding service is almost the same price at about $500+. HS2's fine on unmodified 1300. These are 1 1/4 inch carbs. In modified form all SU carbs can be made to increase flow rates > 30% Here are some more figures I gleaned from various sources: Hi guys, Any thoughts experience on which SU is the better carb for regular road use? Dave you have HS4, go to the library on the black line top of this page and click on tech library , scroll down to carburetors and fuel, read the HS4 sections to give you a bit more understanding of HS4 carbs, you have to loosen the nuts on the linkage bar and adjust each carb seperaley. I have manifolds with vertical carb mountings (1) and offset (2). Since there is already a very good source of starting points/applications for fixed needle carbs, this is for those floundering about in the wilderness that is the biased (swinging) needle example of the breed. Is there any benefit of converting from SU HS4 to HS6 carbs? If so, what all is needed? will the existing intake manifold and linkage work? Anyway, the point of this thread is to establish whether I should be going to the trouble of now overhauling the old carbs and refitting them to the car as there appear to be some slight differences between the two sets. The HS2's were used on the Morris Minors', Midgets and such, while the HS4's were used on the big Healeys. 75") for more potent 1275 models such as the MG Metro and Cooper carb. To be sure, you need to measure the throat of the carb (the big hole that can be seen under the dashpot in these pics) A HS2 will measure 1. However, at speed I think most people find little difference between a single 1-1/2" carb and two 1-1/4" carbs. Other 1300cc with HS4 (Clubman) or HS6. First off on an old HS2 manifold I have Does anyone know the diff in the 3 diff pairs of HS4 carbs listed on the Moss Europe site? For example AUD665F, FZX1258X, FZX1122. Hs4 Su Carb Difference? - posted in Problems, Questions and Technical: Hi guys, Im going to ask a question which might seem a little stupid to a few of you. Best viewed in Google Chrome or Mozilla Firefox (not supported in IE). Can any one offer a comparison between the 2 types? just based on what I am seeing from doing these rebuilds HIF carbs will not wear out as quickly as HS4's and maintain a more consistent fuel mixture. Cheers HS2 for Midget, HS4 for MGB and HS6 for MGC. HIF38 - HIF44 The HIF series of SU is a much later design carby fitted to the later UK minis and mini metro. the dashpot of the carb being sucked up? Why would you trust a separate indicator tool more than the actual carb?) Identifying Su Carb Model - posted in Problems, Questions and Technical: Hi everyone, Possibly a simple problem, but is there a way of identifying which type of carb I have? There doesn't appear to be any markings anywhere that make it obvious whether its a HIF44 etc?? Cheers, Neil. Ensure proper fuel level with precise measurements for optimal performance. HIF4 carbs do not experience the common problem of the HS4 carbs wherein the little hose between the float chamber and the jet leaks (on top of the exhaust manifold). 75") also the main jet bridge is much higher in the HIF44, restricting air flow. Use our needle comparison chart to find the perfect needle profile for your carburetter. What is the difference between the years and is any of them better or worse than the others. The choke is a barrel that turns and opens up a tapered groove to allow more fuel to feed into the motor after the piston and before the butterfly. SU are the manufacturer, Skinner Union, HS is the model, it is reasonably easy to identify as it will have a separate HS2, HS4 and HS6 Carburetter: Dismantling 1 (a) Thoroughly clean the outside of the carburetters. 01 + $20. Does the US 1500 really need dual HS4's, or will the dual HS2's from a 1300 be sufficient for a slightly hotter street car? I have both on my 1500 Midgets, but don't really see much difference in performance between the two. i. The HS2 carb was fitted to the 1622cc Morris Oxford so flow and capacity can be somewhat ignored for the application in hand. Single SU carbs fitted from the factory included HS2 (1. I could MG SU Carbs by model year Carburettors Models by year Classic SU Carburettor HS2 Carb HS4 Float Bowl Lid HS Austin Works Mini MG HS6 $16. HS4's better if intending performance modifications. Bernard, I have a concern about your manifold. While the design is basically the same, they incorporate some emission features, have an integrated fuel bowl and a totally different choke system. HS2 should 1. 25" and the HS4 is 1. e. (The number denotes the size in 1/8" steps from V. you will get lots of help on this site Hi guys, can anyone tell me the way of identifying the different jet sizes for HS2 and HS4 SU carbs. Learn about features, maintenance and tuning. They are fantastic carbs, and a real joy to tune and restore. It can be a real pain if you do not know what HS carb you have. Firstly, what sort of I think you're a little confused on the carb. (b) Standard suction chambers. Post '74 single HS4. ) The HIF type was fitted from about 1973. The main difference between the HIF6 and the HIF44 is that the throttle body bore is smaller in the HIF44 (1. The only advantage of the HIF type carb is that it has a bimetalic strip which automatically adjusts the float according to temperature, so it can compensate for varying fuel density. ---My Setup --- - mid 1970s 998 rebuilt with flat top pistons - 12g295 head ( unskimmed) - 252/252 camshaft - stage 1 (torquemaster Find the correct float height settings for SU carburetters, including T1, T2, T4, and HS models. Jul 17, 2017 · Re: HS2 or HS4 carb by philthehill » Mon Jul 17, 2017 5:18 pm Both HS2 & HS4 carbs will work with the 940 head. MGB HS4 CARBURETTOR ASSEMBLY, PARTS & FITTINGS - RECONDITIONED HS4 CARBS, CARBURETOR SERVICE KITS, CARBURETOR REBUILD KITS, CARBURETOR NEEDLES, FLOAT, LEVERS Twin Hs2's - Try A New Needle Or Swtich To Twin Hs4's? - posted in Problems, Questions and Technical: Hi Guys, One of my minis has a MK3 S engine fitted, the basic spec is as follows. I prefer the HS4 but others prefer the HIFs - I guess it's what you're used to. Your car will have an SU HS4. My question is, should I rebuild the HS or purchase a H4S? And more importantly, are they interchangeable? As explained in the recent Mini Tuning series and book, even small variations in engine specification can radically alter the carburation requirements of an engine. These are all front HS4 carbs, but what differs? Hs2 And Hs4 Carb's - posted in Problems, Questions and Technical: When I fit the stage one kit to my 998cc 73' mini, is it worth changing the HS2 carb to a HS4? * 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. High speed idle is usually around 1800 rpm. 1000cc engines: single HS2 or HS4. Other 1300cc with HS4 Explore HS Type carburetters, known for their side-mounted float chambers and constant depression principle. 25 inch. Su Carburetters are The Worlds Sole Manufacturer of Genuine SU Carburettors, Fuel Pumps and Spares. MK I, II, and III engines prior to 1970 had dual HS2 SUs. 5", same as the HS4). 1100cc engines: HS4. Page 1 of 2 - Twin Hs2 Vs Single Hs4 Vs Single Hif4 - posted in Problems, Questions and Technical: I am a newbie to the forum, and have viewed this forum in the past to find answers for the rebuild of my 1964 countryman, but now I need to ask a fueling question. : H4 = 1 ½. Did the auction state that the manifold was for HS4 carbs? A dual carb manifold for HS2 carbs cannot be used with HS4s. SU Carb Question H2 vs HS2 SU Carb Question H2 vs HS2 Started by pjbowman, December 28, 2008, 03:15:26 Previous topic - Next topic This detailed guide explores the SU carburettor, a constant-depression carburettor widely used in British and European vehicles. A Genuine SU Carburettor Float Bowl Lid - HS6, HS2, HS4 - BARE. I have recently picked up a pair of HS4 carbs and I am looking at what the best manifold is to put them on. 5"), or the metric equivalent HIF38 (Integrated Float chamber) on later Minis and Metros, and finally the HIF44 (1. You state that you bought a dual carb manifold off EBay. These variations can be as obscure as small differences in port or chamber shape, or as obvious as the fitting of larger valves and different manifolds and camshafts. (c) Unscrew the suction chamber retaining screws (3). Moss motors is selling H4 for about $1500 and HS4 for about $800. Both carb modes do the job equally well; the H series were a little more prone to leakage past the old style cork jet seals but if you use the O ring instead there is no functional difference between the two. (d) Lift the chamber assembly (4) vertically from the body without tilting it. The dual HS4's will outflow dual HS2's, but you've got to get a 1500 engine spinning upwards of 5000 rpm to start seeing this difference (as I've been told, no direct dyno experience myself). Find the right needle profile for your engine build. Edited by minimadmike, 13 April 2009 - 04:26 PM. I have 2 carbs both HS4, the one i race with has a red jet fitted, red spring in dash pot with richer needle, but on the float chamber it has what looks like a fuel in and Learn three key methods to identify carburetters in multi-carb installations, including specification tags, driver positioning, and throttle/choke interconnection. Carbs can get fitted with bits from others in the same range so you may find what you have are a bit mongrel. Are there any markings on the carburetors to identify what they are? I want to get a rebuild kit and want to make sure I order the correct one. Note: You can check for matching float settings, after setting the mixture, by removing the pistons, and peering down at the jets. 44 diff ratio, on 12 rims 10. I am not sure mine are in the best shape as I bought used. We show you how to rebuild and tune the popular SU carburetor for your British classic. Secrets of the SU Carburetter - Part 2 Video disassembly of an SU HS2 carburetor continued: operation: float and float bowl, jet and choke operation, tapered needle, air piston breather holes, overrun valve, oil damper valve, HS4 and HS6 differences, MGB and MGC applications, HIF4, HIF44 Just for fun I occasionally look at new SU HS4's. The H1 carbs are also more prone to leaking. 10 shipping. Jan 16, 2016 · What's the difference between HS2 and HS4 on a 1500 engine? And which one is better on a 1500? In reply to # 1341452 by lancepar From what I've read. 2 CR ratio MK3 12G940 head Standard Cam Maniflow Exhaust Manifold RC40 twin box 1 7/8 bore Twin HS2, red springs, M needle, chamfered piston, reduced butterfly The MGB was originally provided with HS4 carbs for all markets, the rear having a vacuum advance port above the butterfly. Twin Hs2 Carb Air Filter - posted in Problems, Questions and Technical: Hello all I'm thinking of installing a Twin HS2 carb in my mini, but I don't have an airbox for the air filter The HS2 is 1. Im a fairly new mini boy and just getting to grips with the carb. Remove the piston damper (1) and its washer (2), if fitted. These have the float bowl underneath. I have swapped one HS6 for two HS2's on a midget with good results. The difference is size (throat bore). Hold the piston firmly and Think I may have confused with my terminology 'slanted'. [frame] [/frame] [frame] [/frame] That's strange R2, the damage doesn't look so bad from here! The world's Sole Manufacturer of Genuine SU Carburettors, Fuel Pumps and Spares. Cooper RSP/Mainstream: HIF44 Metro 1000/Sprite: HIF38 Metro 1300/MG Metro: HIF44 Metro/ERA Turbo: HIF44 [different, special turbo carburettor] What is Can anyone tell me if this is definetly a SU H4 curburetor setup? The engine is a BMC 1622. 5". Expensive but worth it on the right engine. The HIF4 carbs experience less wear on the throttle bushings (due to the way the springs work) and have a temperature compensation device (which some say is not all that reliable). Other 1300cc with HS4 The suction chamber is the same size as a HS4, and held on with three screws. Lots of classic cars have SU carbs fitted. 50" units that came on later SU-equipped MGBs and have a spring-loaded needle and the float bowl sits under the carb body instead of next to it. (Later high compression units solely with HS4 carb) Cooper S and Cooper had twin HS2 carburettors. Yes, HS4 float chambers are easier to get to - but that idiotic little tube that is sealed mostly by wishful thinking sits right above the exhaust manifold. Read on for technical advice for advice on Explanatory Diagram of a Typical H Type Carburetter. In August 1971 with the then new 18V engine all export markets changed to HIF carbs - 18V584Z for North America, 18V581/582/583Y for other export markets. The HIF4 carbs look more modern. 1293 cc GTS Box, 3. There are a couple of different options and was hoping someone would be able to point me towards the option that will give me the best airflow. Actual item pictured - just what is pictured. The HIFs are as easy [or difficult] to rebuild and tune as HS4, the only drawback I've found with HIFs is if there is a problem with the float or needle you need to remove the carb to repair it. Page 1 of 2 - Which Twin Hs4 Manifold - posted in Problems, Questions and Technical: Good afternoon all. Apr 13, 2009 · HS4: HS2: You can see that the dashpot (large silver part on top of carb) is smaller and slimmer than the HS4. The HS4 carbs are 1 1/2 inch carbs that were used on the European version of the 1500 engine, and also on the 1800 engine in the early MGBs. SU carbs work fine with the Spitfire if they are jetted correctly for them. HIF carbs are the 1. The bore of the throat on the HS2 will be smaller than HS4. Nov 29, 2025 · HS2, HS4 & HS6 Carburetter Dismantling – Step-by-Step Guide | SU Carburetters Comprehensive dismantling guide for HS2, HS4, and HS6 carburetters, covering suction chamber removal, jet assembly disassembly, float chamber access, and throttle spindle removal. 73") than in the HIF6 (1. Hi All, After ordering a heatshield off ebay for my 1500 spitfire I have discovered that my carbs are from the original 1300 (HS2's) My engine is a 1500 from a Toledo fitted by the PO ( DM1466HESS (Toledo 1500 reconditioned (ESS suffix defines recon)) Question I have should I be replacing my carbs for HS4's ? or will the HS2's be fine. 25" and the HS4 will measure 1. Looking on Moss they list the SU HS4 in 4 year groupings '68, '69, '70-'71, and '62-'67. In reply to # 4744617 by trevorwj 948 carbs are typically H1 carbs and are 1/8 inch smaller diameter than the HS2 carbs on the later 1098 and 1275 cars. One advantage that HIF4 carbs have that wasn't mentioned was that hard lateral acceleration apparently produces less variation in the fuel level inside the jet. Single Hs4? - posted in Problems, Questions and Technical: I'm trying to decide whether its worth changing to twins or not, and though there are a thousand threads on similar questions i just can't find out what i want! I've currently got a stage 1 1275 with stage 2 head, twin valve springs and an uprated cam, fueled by a single HS4. Compare SU carburettor needles for your Classic Mini with our interactive chart. * (Hypothetical questions: What's the difference between a visual indication by a little indicator button being sucked up the tube of a Unisync, for instance, vs. The HIF38 is 38mm (1. Page 1 of 2 - Twin Carbs Vs. 25") and HS4 (1. 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