TooTallMike Posted December 30, 2014 Share Posted December 30, 2014 (edited) Hi folks, I've got an on-going issue with a customer's Dingo on which I would appreciate some advice (in return for which I will happily make a donation to the forum :-).) The vehicle has been off the road for a couple of years and Richard Farrant very kindly gave me his advice on the finer points of replacing the outer hub oil seals, which was not the most fun job I've ever done. The other major job on it was to sort out the poor running - to be blunt it ran like a dog, with clouds of smoke and sooting up the middle plugs. We concluded the carb was at fault and it was rebuilt by a relative of the customer. He found it was full of crud and the diaphragms were all shot. It is now better but still not right. If you rev it up to around 1/3 revs and then hold the throttle steady it will start to back off and will die completely if the throttle remains held at the same setting. With the air cleaner off, covering 90% of the intake causes it to tick over more slowly but it will then rev up much better. I don't believe it's an air leak anywhere as I've sprayed carb cleaner all round the carb, gaskets and inlet manifold joints with no change in revs. It will drive on full choke but is very rough. Unsurprisingly it is un-driveable off choke as there is no power at all and the engine just wants to die. Petrol is mostly fresh mixed with a small amount of old, but smells fine. The idle mixture jet appears to do very little - when screwed all the way in there is a very slight increase in revs, otherwise it appears to have very little effect. It is currently set at approx 1 turn out as this is the least bad position for it. The lift pump is producing a good volume of fuel at a very healthy-looking pressure. I was just wondering if this could be caused by incorrect float level as there is a small amount of petrol seeping from the joint at the top of the float housing. However the manual does not show how to set the float or the lever it operates. I have heard these carbs can be a horror and that Dingo's always run rich - any comments welcome! I hope i've covered all the relevant points. Thanks in advance - MG Edited December 30, 2014 by TooTallMike Quote Link to comment Share on other sites More sharing options...
G506 Posted December 30, 2014 Share Posted December 30, 2014 Mike, is the carb main jet ok? Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted December 30, 2014 Share Posted December 30, 2014 Mike, Welcome to the wonderful world of Dingos! I would check the float needle valve before thinking of altering the float height. Also, putting in new petrol with stale does not "freshen it up", so might be worth rigging up a small test tank with new petrol in it. Yes they do run rich, also you have to check that it is a Dingo carb as the Champ one is very similar but has some differences inside also the jetting. I have come across Champ carbs being sold as Dingo. cheers Richard Quote Link to comment Share on other sites More sharing options...
TooTallMike Posted December 31, 2014 Author Share Posted December 31, 2014 (edited) Thanks chaps, I fitted a gravity-fed supply direct to the carb containing fresh petrol and it made no difference but it still revs up more freely when the inlet is substantially covered which to me points to either fuel starvation or excessive air (ie. a leak). There is still no position in which the idle jet makes any difference except from being fully done up, to just being undone a fraction, when the revs drop a little. I am now going to take the carb off to look inside it. The carb looks like the one in the manual. How would I tell if it the correct one? The vehicle has done considerable mileage in the past with this carb so I must presume it has run better than this at some point previously! - MG Edited December 31, 2014 by TooTallMike Quote Link to comment Share on other sites More sharing options...
Chrisg Posted December 31, 2014 Share Posted December 31, 2014 Blocked main jet ? Quote Link to comment Share on other sites More sharing options...
TooTallMike Posted December 31, 2014 Author Share Posted December 31, 2014 Everything in the carb is new - it was rebuilt using a NOS 40-odd piece kit which replaced pretty much everything apart from the main castings. I've now had the main jet out back and blown it through along with every other airway and orifice. The main jet comprises two tubes, the inner of which is supplied pressed into the outer. It cannot be further dismantled but there is air getting through so it is presumably clear of obstructions. One thing which I think is odd is that today after re-fitting the carb I ran it without the inlet pipe or air filter and I noticed that when revved up, a quantity of fuel appears round the outside of the low speed jet between the brass of the jet and the casting of the carb. I'm not sure whether this is significant or not since it seems to me the problem is a lack of fuel rather than an excess of it. Chris - are you familiar with this carb from your Champ? If so I don't suppose you'd care to come and have a look would you? There's tea and Xmas cake if that helps... Regards - MG Quote Link to comment Share on other sites More sharing options...
Chrisg Posted December 31, 2014 Share Posted December 31, 2014 Tea & cake help I'm free until Monday 5th Quote Link to comment Share on other sites More sharing options...
singaeger Posted December 31, 2014 Share Posted December 31, 2014 Hi Mike if you get no joy in resolving the problem I'm happy to run down to you and lend you a good carb for a day. This will at least prove where the fault lies. That's assuming you are in the gat wick area. might also be able to help with some carb spares can I ask the number of your car. I run the dingo register site regards singe http://www.daimler-fighting-vehicles.co.uk Quote Link to comment Share on other sites More sharing options...
martinsaunders06 Posted January 1, 2015 Share Posted January 1, 2015 Hi Mike, I looked at a dingo with terrible rough running , It excess visible fuel around the lower carb etc - turned out the carb float was porous and partially full of fuel flooding it , tho oddly enough it too ran better with more choke which is the opposite to the obvious . Drilled a hole in it and emptied out and soldered all seams back up . Was ok martin Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted January 1, 2015 Share Posted January 1, 2015 The "choke" on a Dingo carb (and other military vehicles of the era with Solex carbs) is not a choke in the general sense. It is a small metering unit on the outside of the carb and only works when the throttle is shut and draws air in from outside of the main carb body. It is called a Zero Starter. The reason the engine is running better when choke is applied on a rich running engine (ie fuel level too high), is probably because it is actually drawing more air in to it than less. cheers Richard Quote Link to comment Share on other sites More sharing options...
TooTallMike Posted January 2, 2015 Author Share Posted January 2, 2015 Thanks folks, ChrisG and I spent most of today on the Dingo and are none the wiser. We have however established some of the obvious differences between Dingo and Champ carbs which was interesting and seems to be mainly in the accelerator pump. We have now established that putting a hand over the inlet masks the problem rather than curing it, so that should be disregarded as a clue. Essentially it seems to be overfuelling to the extent that it is drowning plugs 3 & 4 which then causes rough running. Both these plugs have a healthy spark when out of the engine but when fitted for any period come out wet, especially no.3. Compressions have been checked and are ok. We cured the fuel leak mentioned in my previous post - it was leaking out between the carb casting and the vertical brass accelerator jet within the inlet orifice. This was cured by fitting a trimmed-down 'o' ring under the register to seal it up. The fuel now comes out of the hole in the jet as it should. However there is a hideous delay between briskly opening the throttle, and the fuel appearing out of the accel pump jet, and then it being drawn into the engine and the revs actually increasing. I presume this is down to the accel pump being operated by depression in the inlet rather than what I would consider to be a more conventional mechanical linkage. Is this delay normal? Singe - PM on its way! To be continued... - MG Quote Link to comment Share on other sites More sharing options...
TooTallMike Posted January 2, 2015 Author Share Posted January 2, 2015 I forgot to mention - ChrisG is going to bring over a Champ float chamber tomorrow as this will replace the main jet and accelerator pump in one go and we'll see if that makes any difference. - MG Quote Link to comment Share on other sites More sharing options...
TooTallMike Posted January 3, 2015 Author Share Posted January 3, 2015 We just swapped in a Champ float chamber which made pretty much no difference to the running. This means it is unlikely to be the main jet or accel pump since these are fitted to it. - MG Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted January 3, 2015 Share Posted January 3, 2015 Mike, Maybe you are barking up the wrong tree and it is an ignition problem? A reverse on the GMC saga :undecided: Quote Link to comment Share on other sites More sharing options...
fv1609 Posted January 3, 2015 Share Posted January 3, 2015 Mike if you have any anxieties about the state the ignition components bring them to the Dallas Sortout & I can use my box of tricks Quote Link to comment Share on other sites More sharing options...
wally dugan Posted January 3, 2015 Share Posted January 3, 2015 following on from Richards post have you checked the spark plug leads are fitted in the right firing order and two have not been swopped over had a similar problem on a morris commercial engine Quote Link to comment Share on other sites More sharing options...
TooTallMike Posted January 3, 2015 Author Share Posted January 3, 2015 Mike,Maybe you are barking up the wrong tree and it is an ignition problem? A reverse on the GMC saga :undecided: Indeed Richard, I am painfully aware of that possibility! Unfortunately we don't know whether the plugs are wet because they are receiving too much fuel, or whether it is because they are not firing. We have happy sparks on all six when they are out of the engine but of course no guarantee of what is going on inside. - MG Quote Link to comment Share on other sites More sharing options...
TooTallMike Posted January 3, 2015 Author Share Posted January 3, 2015 following on from Richards post have you checked the spark plug leads are fitted in the right firing order and two have not been swopped over had a similar problem on a morris commercial engine We re-checked that this afternoon but thanks for the thought! - MG Quote Link to comment Share on other sites More sharing options...
Adrian Barrell Posted January 3, 2015 Share Posted January 3, 2015 I have recently been sorting through a friends Dingo. Rebuilt the carb and it ran well but only for about half a mile! The spark was ok, though seemed to be jumping around the electrode somewhat. I fitted a replacement coil and that sorted it, was obviously breaking down when hot. Quote Link to comment Share on other sites More sharing options...
fv1609 Posted January 3, 2015 Share Posted January 3, 2015 Mike as you know under compression the gas density requires a much higher HT for a spark to occur. It is good that you are getting sparks at the plugs when you can observe them in air. The plug gap of course of is very tiny & you may have an inadequate HT although it is managing to spark at the plug in air. It would be a better test of the HT to remove a plug & cautiously hold the end connector of the HT lead at a distance of about 1cm from an earth point. If can't jump that there is inadequate HT. It would of course be worthwhile doing that to each lead to verify its status. In the last year I have tested at least 6 Dingo coils & I think only 2 of them were satisfactory. Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted January 3, 2015 Share Posted January 3, 2015 We re-checked that this afternoon but thanks for the thought! - MG Mike, Good idea to swap wet plugs to another location and check again, they may be breaking down under compression. If it has the screened plugs, I know from experience they can foul and even with new ones they do not perform as good as when discarding the screened leads and fitting conventional with modern plugs of equivalent heat range. It depends on which distributor it has, as to whether this can easily be done (dustproof v. waterproof). Quote Link to comment Share on other sites More sharing options...
TooTallMike Posted January 3, 2015 Author Share Posted January 3, 2015 (edited) It would be a better test of the HT to remove a plug & cautiously hold the end connector of the HT lead at a distance of about 1cm from an earth point. If can't jump that there is inadequate HT. It would of course be worthwhile doing that to each lead to verify its status. Hi Clive, We did this and all of them jump a good 10mm or more with a nice blue spark and a 'crack' which is audible even above the sound of the engine running. - MG Edited January 3, 2015 by TooTallMike Quote Link to comment Share on other sites More sharing options...
gritineye Posted January 3, 2015 Share Posted January 3, 2015 Sound very much like a progression jet issue to me Mike. Quote Link to comment Share on other sites More sharing options...
TooTallMike Posted January 3, 2015 Author Share Posted January 3, 2015 (edited) Mike,Good idea to swap wet plugs to another location and check again, they may be breaking down under compression. If it has the screened plugs, I know from experience they can foul and even with new ones they do not perform as good as when discarding the screened leads and fitting conventional with modern plugs of equivalent heat range. It depends on which distributor it has, as to whether this can easily be done (dustproof v. waterproof). Hi Richard, Plugs have been swapped about and any plugs fitted into 3 & 4 wet up again immediately while the removed ones immediately work fine in other cylinders. There are also five spare used plugs which have been included in the mix. Plugs fitted in 3 & 4 always come out glistening wet with petrol - my interpretation was that they are receiving so much fuel they are unable to spark, but thinking about it is that realistic or am I mis-interpreting it? I also tried pre-heating the plugs on the stove but again no improvement. The plug lead screening has already been removed and the leads are modern copper-cored type, fitted into the screened distributor and run as exposed black plastic leads up to the right-angle connectors which are screwed down to 'original' screened plugs. I would be very pleased to do away with these and fit standard plugs and lead ends to facilitate testing but I don't think the customer will go for that unless there is a compelling argument. - MG Edited January 3, 2015 by TooTallMike Quote Link to comment Share on other sites More sharing options...
TooTallMike Posted January 3, 2015 Author Share Posted January 3, 2015 Sound very much like a progression jet issue to me Mike. Hi Bernard, I am hoping to take Singe up on his offer of a known good carb as we need to start eliminating components. I also hope to ask him to bring a set of plugs, leads and distributor cap so we can address that side of it too. Rgds - MG Quote Link to comment Share on other sites More sharing options...
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