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Car Forum / MINI / June 2004Exhausted!!!!!
OK, ive put on the K&N filter, LCB straight through and twin upswept DTM style back box. Started the engine and frightened all within ershot of me mini!!!!! Runs like s#*% Sorted the timing, still not running right hmmmmmmmmmmmmmm Start engine pull out choke, VERY LOUD and runnning fine, wait till engine gets to temp, put choke in, still wont run but does tick over. Is the engine too lean? Where is the mixture screw on a SU? I'm thinking its too lean coz when I pull out the choke the engine runs fine, but put it in gear, drive away after a cough, splutter and a pop, gets moving, pull out choke and it sets off like a rocket. The LCB is 3 Branch into Y piece in 2" pipe and exiting through a 2" back box I had lying around. Please can anyone help coz I can't find the mixture screw. Is it me being fick. BTW no manual yet but will get around to buying 1 soon Thanks in anticipation. Matt Did you change the needle? Dean. > OK, ive put on the K&N filter, LCB straight through and twin upswept DTM > style back box. [quoted text clipped - 28 lines] > > Matt Nope A: haven't got another B: couldn't see the need as it's standard engine... I really think its just the mixture > Did you change the needle? > Dean. [quoted text clipped - 32 lines] > > > > Matt listen to the man, its the needle jono  SignatureBarspeed Mini`s - Devoted to the Classic Mini "Persisto Transverbero Adversum" Email - barspeed@hotmail.com The Rover Mini Se7en Register - http://www.geocities.com/minise7en2001/ Barspeed Mini`s - http://barspeed.topcities.com Barspeed Mini`s Group - http://groups.yahoo.com/group/barspeed Barspeed Motor Album - http://barspeed1.topcities.com If you have received this email in error please click below. barspeed@hotmail.com > Nope > [quoted text clipped - 41 lines] > > > > > > Matt > listen to the man, its the needle > > jono Yup, 100% Go to Amazon or similar, buy a copy of How to Modify your Mini, or Tuning BL's A series engine, both by David Vizard, read, understand and inwardly digest. The SU carb works in a different way to most, adjusting the mixture only affects the idle mixture, the mixture above idle is controlled by a finely tapered needle. Having changed the air filter and manifolds you have altered your engines fueling requirements, hence a needle change is required. Try http://www.winsu.co.uk to give a needle guide, but to get it absolutely 'spot on' would need a trip to a dyno tuner. Drew. www.rileyelf.co.uk OK I'll give it a go. Thanx 2 everyonr for the help regards Matt > > listen to the man, its the needle > > [quoted text clipped - 14 lines] > > www.rileyelf.co.uk Oh, just had another thought.... these could very well be symptoms of an inlet manifold leak, check your carb gaskets did not get folded in when you re-fitted the carb, or the manifold gasket did't get damaged. Drew. > OK I'll give it a go. > [quoted text clipped - 22 lines] >> >>www.rileyelf.co.uk INSTANT GASKET works wonders for an engine LOL The engine now fires up and runs like a dream........on tick over. But the acceleration is loads better and smoother. There must have been a leak on one of the gaskets. Thanx drew. Just gotta go and find another needle now, oh and some cash to but it. Wahoo pay day next week....... > Oh, just had another thought.... these could very well be symptoms of an > inlet manifold leak, check your carb gaskets did not get folded in when [quoted text clipped - 28 lines] > >> > >>www.rileyelf.co.uk drew <drew@xxxrileyelf.co.uk> wrote in news:40d4afb3$0$8250$ed2619ec@ptn- nntp-reader01.plus.net: > The SU carb works in a different way to most, adjusting the mixture only > affects the idle mixture, the mixture above idle is controlled by a > finely tapered needle. Not entirely true - adjusting the mixture affects it over the whole range ( have looked at this and tested with a gas analyser ), what it doesn't do is change the mixtuxe at a specific point in the range - which is what is required when you're letting a lot more air in at idle and the top end. So yeh - a new needle... Was it AAA or AAM or something someone was suggesting a while back? S. > So yeh - a new needle... Was it AAA or AAM or something someone was > suggesting a while back? yeah - these are the common needle types for a stage 1 kit - which is basically what matt has now got. just slapping one of these needles in is still no good - it will need a rolling road sesh to get all the power out over the rev range. - seriously - i have first hand experience - tried multiple needles with mine, checked gasses on idle etc but finally gave in and took it to rolling road - the bloke got another 10 bhp at the flywheel for me (which is a lot if you only have 55 in the first place!) cheers Ryan >A: haven't got another After finding out which needle you need, buy it from any mini shop. Minispeed or Minisport would be my choice. They are about 8 quid each. >B: couldn't see the need as it's standard engine... Ah, a mistake we have all made (including me). By sticking on a K&N and big exhaust you have massively increased the gas flow. More air will be flowing into the carb, but the fuel flow has not also been increased. The result is a lean top end. >I really think its just the mixture It *is* the mixture, but the mixture screw only adjusts the idle mixture. The needle profile controls the fuel/air vs revs. You will get to a rough ball park with WinSU but a rolling road session is the only real way to get it right. Do not be tempted to run with it lean, you'll do allsorts of damage to your engine and the next MOT emisions test will fail, not to mention sod all power from your new mods. Once it is set up right, then you'll get the big power increase which you are after. Scott OK I'll stop running it now. Ive only ran it for a couple of miles, to try and sort out the little tweeks and stuff. I'll tell you what tho just by putting on the K&N and the BIG exheaust what a difference. Any idea how much BHP its running at the mo? I,m guessing around 50 ish. > >A: haven't got another > [quoted text clipped - 20 lines] > > Scott >I'll tell you what tho just by putting on the K&N and the BIG exheaust what >a difference. Wait until you get it set up right then you'll need a G-suit! ;-) >Any idea how much BHP its running at the mo? WinSU will give you an idea, a decent stage 1 998 (filter+zorst) will give around 50-60bhp, whereas a stage3 998 (+295head) will give about 70bhp. My 1330 with head/cam/allthetrimmings gives 84bhp...better power to weight than a golf VR6! :-) >I,m guessing around 50 ish. a rolling road will tell you, best bet is to join a club and get along to a dyno shootout day, much cheaper than a full tuning session Scott Thanx Scott for all ur help. These newsgroups are brilliant. 4-2 come on INGERLAND LOL > >I'll tell you what tho just by putting on the K&N and the BIG exheaust what > >a difference. [quoted text clipped - 14 lines] > > Scott your first mistake was the one all folk new to Minis and or car tuning make...before you buy "go fast" or modify bits buy a reputable manual so you have some Idea of what your doing...best money you'll ever spend > OK, ive put on the K&N filter, LCB straight through and twin upswept DTM > style back box. [quoted text clipped - 28 lines] > > Matt >OK, ive put on the K&N filter, LCB straight through and twin upswept DTM >style back box. >Started the engine and frightened all within ershot of me mini!!!!! >Runs like s#*% I take it you changed the carb needle? Go to http://www.winsu.co.uk download the prog and find out what needle you need and then buy it. If you stuck a big zorst on, the needle will need changing, else it will be way way too lean at top end and you'll melt your pistons. Scott Creator of The Mini Internet Encyclopaedia http://www.ime.org.uk Nope not yet! Only just got in from work. Need food LOL And a brew oh and a carb needle... TY for asking tho.. Matt > >OK, ive put on the K&N filter, LCB straight through and twin upswept DTM > >style back box. [quoted text clipped - 10 lines] > Scott > Creator of The Mini Internet Encyclopaedia http://www.ime.org.uk > Nope not yet! > Only just got in from work. [quoted text clipped - 4 lines] > > Matt Matt, exactly what carb are you using? The SU HIF series, as others have said, cannot have its mixture characteristics changed throughout the rev range - only the idle mixture can be altered. However if you have the older SU carb (with the float on one side - l/h from the front of car) then it is possible to adjust mixture strength at all revs. If you look at the bottom part of the carb while moving the choke cable you will see that the whole of the bottom part moves down. The choke works by moving the jet further away from the needle - the bigger gap between needle and jet gives the richer mixture. This whole assembly can be moved up (leaner) or down (richer) by screwing the big brass nut up or down. Its easy done - but obviously only on the older carb! A quick service - new filters plugs points etc - and a bit of a fettle with this had my std '72 mini 1000 doing 95 no probs with a single 1 1/4" and std zorst & filter. chris It's the standard carb. 2 Nuts holding it onto the inlet manifold. But I have an ace up me sleeve, got one from a 1275 MG Metro sat waiting in the shed ready to put on when I put the bigger head onto the block. The car itself is a very sorry looking MINI Studio 2, of 1991 Vintage. So the carb is probably of the newer type maybe? > > Nope not yet! > > Only just got in from work. [quoted text clipped - 21 lines] > > chris > Matt, exactly what carb are you using? The SU HIF series, as others >have said, cannot have its mixture characteristics changed throughout the [quoted text clipped - 3 lines] >bottom part of the carb while moving the choke cable you will see that the >whole of the bottom part moves down. I'm sorry, but this is complete nonsense! The HIF also moves the jet down, it is just integral to the float chamber. Neither HS nor HIF allows you to fine tune the mixture at specific rpm. Moving the jet up or down changes the whole range in one hit. If you need more top end relative to idle then this can ONLY be acheived by changing the needle taper. One other thing which is often overlooked is the dashpot spring. A tuned motor will need a stronger dashpot spring or else the needle will 'top-out' too soon. This often makes the mixture go too rich at the top end as the needle stops rising and the air speed keeps increasing (remember it is the air speed over the jet which sucks out the fuel, not the needle lift letting the fuel dribble out). The spring needs to be tailored so that max lift occurs at max revs (6k for road, 8k for race). On top of that 'load' is not the same as 'revs' (up hill in 3rd at 3k can open a carb fully) so you need to think about that too. And then there is 'accelerator pump' effect which is why we put oil in our dashpots. It is trail and error. Patience! This is why a rolling road sesh is money well spent. Carb tuning is not as simple as it looks. I run twin HIF44s and it's taken me years to get them right. Sometimes a laptop and mapped injection looks so much more attractive! <washes mouth out with soap!!> Scott |
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