My lad got his mk2 a couple of months back. Had a new looking weber 32/34 dmtr fitted. First real drive to get mot last week where it failed on emissions. I found all the primary and secondary jets ar5e about face. I swapped them back but now it idles like cr@p. I cant get a good idle no matter what. When you just breath on the throttle it stalls. Jabbing the throttle avoids stalling. All the jets are correct for a 1.3 ie 45 primary and 70 secondary idle. These are good carbs but at this rate im taking my sledge hammer to it!! Any help or advice welcomed
Make sure the idle jet is clear and not blocked with any debris. The jet size is around 0.5 of a mm so does not need much to block it. Be careful when removing the jet stacks as it is possible for the complete idle assembly to fit down the hole that the main jet assembly came out of! I learnt that lesson the hard way. Carb off and turn upside down is the only way to get it out. If the primary idle jet is clear then possibly the mixture screw needs adjusting as it may have been set for the wrong size jet that you have since swapped around. The mixture screw is located right down on the rectangular mounting flange on the primary choke end. It goes in horizontally and is adjustable with a small plain screwdriver that can fit up the casting hole.
THanks Danster. I've made all adjustments comprehendable to man and it's still exhibiting the same issues. Its tricky to see into the idle jet circuit even with the carb off, however we suspected a small ali fragment/swarf might be restricting it. Just lifting the primary idle jet half a turn will solve the problem. Trust me when I say the primary idle jet is clean and clear......cleaned and poked to check it and i can see perfectly thru the hole with my magnifier. This is the nearest digram I can find on the web. Item 44 doesn't exist on ours. The car will idle but its not great, however just a feather weight on the throttle at slow speed will make it stall the engine. In my mind it's the idle circuit but this is also linked to the progressive opening jets in the venturi, around the butterfly.....and it's this system that's not working I believe. I can drive the car ok by snatching at the throttle to drive past the problem, but it's a git.
If the idle jet is clear then possibly there is debris in the carb float bowl that is restricting the flow of fuel to the idle circuit. I presume you are 100% sure of which is the primary and secondary jets. Much as it is a bit of work, a carb strip down to make sure the float bowl and various drillings are clean would be a good starting point. Have you made sure all vac lines are connected? IE servo pipe not leaking, and vac dizzy line too? In fact check the vacuum module on the dizzy as they can fail and allow air to be drawn in through the diaphragm. A good suck on the line to see if it holds a vacuum is a test on that one.
Yes - the primary / secondary jet order has been researched and checked on several websites and they all concur. Originally the jets were ar5e about face. The carb was laid in bits on the kitchen table on Monday night......a few specs of ali and couple of grains of something which were cleaned out of the float bowl.......and then WD40 and oodles of compressed air in all orifices (and holding fingers over jet holes etc......like we were playing bagpipes ) All vac lines are connected and the hoses are new ones. I will test the dizzy diaphragm - will blank off the connection on carb for a start. I don't quite understand how the main jet / air correction / emulsion tube feeds air/fuel mix to the venturi and exactly how it relates to the idle jet and idle mix screw......despite the drawing above ^^^ [:^(]
This is because the art of the carb involves years of focussed study. Only when you truly concentrate on the science of the carb and shun all other wordly interests will you become a master of carbs! Unfortunately there is a drawback as there is little time to engage in more normal life activities such as washing and shaving. Note the angst on this carb guru's face as he takes a break from balancing and adjusting a set of Quad Triple Downdraughts.
Looks like I feel lol ^^^ I'm a mechanical engineer by profession and have studied venturis and jets, but not carbs as such. I still suspect a blockage The mixture screw is about 4x turns out........IMHO this should be 2 or less
I have a sneaky feeling this piece of well engineered moon cheese will succumb to my club hammer shortly......280 of utter boswelox. Have resorted to digging out an old pierburg we have and putting that on for now........autochoke yeukk! But if it works, it works.........having said that - I havent tried it yet.
It doesn't have the electrical cut off solenoid fitted by chance? Some carbs have it and it would be on the far side nearest the bulkhead on a 1300. If so then it will need a 12v supply, they are fitted to stop running on and emission bollox. That would effect tickover if not connected. Weirdly the small block engine mount the carb 180deg out compared to the big block type.
I had looked at this myself already and notice only the 1600 and 1800 DMTR / DMTL have the shut-off solenoid. On this version the port is capped off. I have a feeling there's a blockage on the primary idle circuit..... I may have to prize out one of the drillings copper side caps to get access to the circuit - there seems no other easy way!
Could you not blow back through the idle jet orifice with the jet stack removed. Just be careful petrol does not go eveywhere and get on you or cause a fire hazard. Blowing it clear with an airline would displace any debris back into the float bowl reservoir and it should run clear then. At least till any dirt if there is any finds it way back to a jet. Another thing is that because the carb is reversed so to speak on the 1300, are you 100% the primary and secondary jets are in the right place. It is just that you mentioned they were wrong before, but the carb is on the other way round so could lead to confusion on that. Easy way is just to look down on the carb from above and you can see the passage ways from each choke to their relevant jets. Primary is nearest the bulkhead on your car, secondary next to spark plugs.
Dan I've had the carb completely off the car.......taken the top half off, removed all jets and stared into the orifices for an eternity - and I thought we had washed and blown out the debris we found using my air line and gun.......there was some grainy odds and ends and a bit of Ali swarf. I still think there's a bit we never managed to budge Yes mate I am pretty sure about the jet order.........have checked originally using this image I found on the web;- http://www.flickr.com/photos/55777341@N00/5464599813/ "Having struggled to find a web site that explained how to swap jets in a Weber 32/34 DMTL I thought I'd have a go. 1. The 4 jets are shown in the middle of the picture. Unscrew to remove. 2. Looking from the front of the car with the throttle linkage on the right, the 2 PRIMARY jets are on the left, the SECONDARY 2 are on the right. 3. From left to right they are Idle Jet Primary Main Jet Primary Main Jet Secondary Idle Jet Secondary 4. The Main Jet is made up of 3 parts as in the pictures below. 5. For a Volkswagen 1.8 engine the jets are Air Corrector Primary 145 Secondary 200 Emulsion Primary F30 Secondary F33 Main Primary 120 Secondary 140 Idle Primary 55 Secondary 60 The markings are stamped on each jet, very small. 6. For a VW 1.6 engine the jet sizes are Air Prim 155 Sec 155 Emulsion Prim F30 Sec F25 Main Prim 120 Sec 125 Idle Prim 55 Sec 60" Yes, as you say - the carb is 180 degrees out compared to big block manifold but i've allowed for that. I also double-checked this order by loosening the primary jets at idle and seeing the effect........the secondary jets made no effect at idle.
Ok, the primary is also easily identified as it has the choke butterfly on it. (missing a screw in whoevers pic that is!) You can see the mixture feed channels to the auxiliary venturi in the picture, which are lined up towards their respective jet stacks. This being the case your primary idle jet will be on the right hand side as you look at the carb from the front of the car. Was the car ever running right? I can just make out the petrol pump on the right, meaning this is a hydraulic tappet engine so has electronic ignition, eliminating points and condenser woes. MH or 2G code per chance? Air leaks may be the cause of running issue, are there any open vac lines that would normally connect to the airfilter warm air blend system. They could draw air if not capped whilst the air filter housing is removed and trying to run the engine.
I appreciate your help chap.......... It's a 2G with pump on right....yes electronic ignition (89 year G-reg 4+E in lovely Gold ) I have replaced the small vacuum hoses (I have a 10m roll of the cotton covered 3mm hose.....slowly dwindling!) and checked the unused connection is properly blanked off at the carb. I've jetwashed the engine and let it dry then started it and dumped half a can of WD40 around all the inlet manifold joints and connections but nothing amiss - no obvious vacuum leaks. The car made black smoke like a diesel when we first got it - and this I put down to the idle screw being way out. Driving it to the MOT station - it drove OK low down but was seriously holding back once second venturi was "in play"...... The emissions were way out at idle proving the primary idle jet was oversized. This is when I realised the jets had been swapped around by previous owner :/ I had thought we might have a burned out valve however I've experienced this myself on a Mk1 years ago and it's not got the same type of issues so I have ruled it out. I was just reading a club polo thread and one of the guys on there has his emulsion tubes reversed compared to ours.......but I think this would just affect the main fuel delivery venturi. http://www.clubpolo.co.uk/forum/index.php?showtopic=145786
Well, after another 2 hours faffing about with the carb again in component pieces - I would like to surmise that there's nothing amiss with the carb. Probing with tiny wires into all circuits (as far as we can), and squirting freeing oil into channels - then using compressed air to check and test - makes me think there's no blockage to speak of. Maybe there was some blockage and now there isn't? however we didn't find anything conclusive. Next step is to strip down the intake manifold and check absolutely all possibilities for a vacuum leak. Deep joy...........
OK, well after refitting the carb and a brand new distributor off a polo 1.3, the car seemed to run nicer. The car drove ok, but seemed to have a bit of a misfire but only when labouring the engine in higher gears. The clutch was jeffed so we bought a new one. On Saturday we took the 4+E gearbox off the car. Looked like the original clutch so had done ok for 100k on the clock. The gearbox input shaft was visibly leaking tranny oil and second was a bit crunchy on way down the 'box, so we elected to swap it for a Polo 1.4 geabox we had - with low miles. The selector mech and one output cup needed swapping to make it work - and we found the ratios were same although final drive meant 5% lower revs across range. Got that finished and all seemed nice. Due to serious oil leak from head gasket, we got started on renewing it. Stripping ancillaries and removed head. Removed all the valves and examined them...they were fairly coky on the inlet side, so cleaned them thoroughly and lapped all 8x valves in, renewed stem seals and then replaced everything. Cleaned all the faces thoroughly. New head gasket, new head bolts and torqued down as specs. Replaced cam belt using the marks we painted on...the belt timing was also checked and all correct. The car fired up but was *really* misfiring. After a moment it was better although not great. At idle the car is definately misfiring. We did find one duff spark plug ( a new one!) but that was replaced and still not 100% correct. We have replaced dissy cap, rotor arm, king lead, coil, igniton amp and checked all wiring and connections. Despite the misfire at idle, the car seems to run really fine once its going along.... Going slowly mad here now
Have borrowed a compression tester and the cylinder pressures are within 10% which is great news Have put a third set of plugs in which made no difference. The last thing to swap is the plug leads...........best get some and try 'em.......fingers crossed!
Have tried 3 spare leads we borrowed off a Polo and they made no difference. I am starting to suspect hydraulic tappets, as the valves moved nice and freely in the guides. Jeffed lifters can cause misfires....or so I have read
Have found a spare (used) set of hydraulic tappets in my parts stores..and have taken them apart - cleaned them a bit and removed old oil. Off with the cambelt, and cam....removed the old set and replaced them with the used set...reassembled. Tried the engine and it ran with noisy tappets but *not* a misfire !! So that decided it......off to GSF parts to get a new set. 58 quid later - cambelt off - cam out again.......old ones out and new ones in. Started the car up and what d'ya know....quiet as a lamb and no misfire!! The engine sounds really nice now HOWEVER there is still a problem. The engine sometimes hesitates and flutters when moving away from idle revs. Personally I think it's a minor carb problem still. I am gonna look out for a known working carb and try it. For now the car's usable and running nice
