neil spencer Posted March 17, 2014 Share Posted March 17, 2014 I have a problem with my 1972 mk2 2000. It runs on Stromberg HSE's I believe is the correct title.Whilst driving it gives all the signs of badly out of balance carbs, or timing a long way out. The car lurches whilst accelerating, on the overrun and even when driving at 2-4 thousand revs you can feel it. (never gone above this).The engine has done a genuine 49k from new. Compression is spot on. It burn no oil. It starts instantly when cold with no knocks or rattles etc. I have just had a set of strombergs fully reconditioned and fitted and set up by an old school expert who does this for a living. Balance and readings were perfect. The original set would not richen up enough even fully adjusted. The new set came out spot on with his sun tune up kit- all readings were spot on. We cannot find an air leak anywhere. The engine has a good vacume so eliminating valve timing problems.I don't like strombergs. Sick to death of them on my Stag. I have a 2.5Pi and I swear by this system. This is the first big saloon I have had with carbs, in fact it's my first 2000 as all the others have been 2.5 Pi's so my knowledge is a bit lacking.Any idea's anyone? :(Neil. Quote Link to comment Share on other sites More sharing options...
Richard B Posted March 17, 2014 Share Posted March 17, 2014 I actually quite like Strombergs, although I prefer PI's. Strombergs tend to stay in tune longer than SU's. Are you sure that the diaphrams are ok and there is not a small flaw or tear?Could it be a fault in the choke mechanism on the side, have you tried spraying WD40 on the carbs whilst the engine is running to try an locate any leak? Quote Link to comment Share on other sites More sharing options...
nicmk1est Posted March 17, 2014 Share Posted March 17, 2014 t t t timing ;) Quote Link to comment Share on other sites More sharing options...
Nick Jones Posted March 17, 2014 Share Posted March 17, 2014 Problems with two sets of carbs..... Maybe it's an ignition problem?Nick Quote Link to comment Share on other sites More sharing options...
neil spencer Posted March 17, 2014 Author Share Posted March 17, 2014 The carbs have been completely rebuilt with new parts including diaphragms. The pistons lift smoothly and evenly.We have sprayed easy start to try to locate leaks, plus brushed on neat petrol with a brush on all joints.The choke works freely and has new gaskets.I replaced the original electronic ignition with a new one plus plugs, leads, cap and coil. Removed ballast resistor as coil is 12v sport coil.Timing is now set at 9 degrees before tdc.I am beginning to wonder if I have a sticky valve? Grasping at straws now, but I bet when I get to the cause of this problem it will be something stupid and simple.Neil. Quote Link to comment Share on other sites More sharing options...
nang Posted March 18, 2014 Share Posted March 18, 2014 Are you sure the valve timing is correct or the front pulley marks are corect ? You could try advancing the timing until it pinks then retard it a bit and see where your timing marks are.Tony. Quote Link to comment Share on other sites More sharing options...
neil spencer Posted March 18, 2014 Author Share Posted March 18, 2014 Tried a vacuumed gauge on inlet manifold at servo point. Reading was 15 and to my mind you just wouldn't get that if valve timing was out. Maybe I am wrong but I haven't removed timing cover to check. I would expect fuel to spit back out of carbs too if valve timing was out but I may just have to check this as I have run out of ideas. It's not a 5 minute job though with rad out, fan and pulley before timing cover. I wouldn't want to go that far without replacing the chain etc anyway.Thanks for all the suggestions and keep them coming.Neil. :) Quote Link to comment Share on other sites More sharing options...
DougBGT6 Posted March 18, 2014 Share Posted March 18, 2014 15 sounds a tad low, I would have thought up around 19/20 was ideal. You can set the timing using the vacuum gauge, here is a link. http://www.classic-car-magazine.co.uk/articles/tuning-with-a-vacuum-gauge.html Quote Link to comment Share on other sites More sharing options...
neil spencer Posted March 18, 2014 Author Share Posted March 18, 2014 Sorry in my despair I have got confused. The reading was actually 19 on the vacuum gauge, and the hydro-carbons were at around 250, where if the valve timing had been out they would have been around 1000? Am I wrong on that? Not sure of anything any more.I am getting rather frustrated and annoyed with myself over this problem as I am convinced it will be simple when I get to the answer. The old grey matter has seen better days I think.Maybe I should just buy an MGB? ;)The link was very interesting and I have learned something new today. Trouble is I have had to un-learn 4 things just to fit it in my head. :BNeil. Quote Link to comment Share on other sites More sharing options...
DougBGT6 Posted March 18, 2014 Share Posted March 18, 2014 Don't despair, you know more than you think. I know nothing of these hydro-carbons of which you speak! :K) I've had body work done at an MG garage. MGs seem more solid to me than triumphs but heavier, not as fast and not as pretty. Other things to check, manifold gasket, unlikely with a vacuum of 19 but could be leaking when you put your foot down. Also when you put the carbs back did the gaskets have a strange cut out which should align with a hole in the carb and manifold? I've put this back wrong twice! Quote Link to comment Share on other sites More sharing options...
Straight Six Posted March 18, 2014 Share Posted March 18, 2014 Is the centrifugal & vacuum advance/retard mechanism free to move & working correctly? Quote Link to comment Share on other sites More sharing options...
Richard B Posted March 18, 2014 Share Posted March 18, 2014 Coil? Quote Link to comment Share on other sites More sharing options...
neil spencer Posted March 18, 2014 Author Share Posted March 18, 2014 Distributor works as it should both on centrifuge and vacume.The coil has been replaced but I will change it again today just in case I have a duff one.I am going to check timing again too though it's been checked at least 4 times!!!!Keep em coming lads, someone will make the right suggestion I am sure.Neil. Quote Link to comment Share on other sites More sharing options...
nicmk1est Posted March 18, 2014 Share Posted March 18, 2014 is the rotor arm in good condition/has it been changed,,,load of crap arms out there(beware) Quote Link to comment Share on other sites More sharing options...
neil spencer Posted March 18, 2014 Author Share Posted March 18, 2014 I changed the rotor arm along with the electronic ignition very early on in this saga.It is a red one that came with the powerspark electronic ignition kit.Needless to say it made no difference.Neil. Quote Link to comment Share on other sites More sharing options...
nicmk1est Posted March 18, 2014 Share Posted March 18, 2014 seeing as you have checked everything,carb,ign system etc what about the fuel pump? is it feeding enough pressure to keep up with demand Quote Link to comment Share on other sites More sharing options...
Russell Posted March 18, 2014 Share Posted March 18, 2014 I know you said the distributor works as it should both on centrifuge and vacuum, but have you tried running without the vacuum advance connected?The Mallory on my Rover Engined Stag was giving me erratic behaviour on pulling away and removing the pipe cured the issue. It probably has a weak mechanism, but in the end I just blocked up the ports at both ends.Failing that, I would be tempted to try another distributor if you have one.You could also try putting 12v direct to the coil from the battery, to elimitate any issues with the ignition circuitry. Quote Link to comment Share on other sites More sharing options...
neil spencer Posted March 18, 2014 Author Share Posted March 18, 2014 I haven't actually checked the pressure but I don't think this is the problem to be honest.It's not a fuel starvation type of symptoms really.On the original carbs we couldn't get the Co up over 3% so I was convinced the carbs were leaking air. A new reconditioned set were easy to set at 4% and I thought we had cracked it, but on the test drive it was no different!I am fairly sure ( though not completely) that I have eliminated the carbs and ignition, and the valve timing so I think the heads going to have to come off unless someone can point me to something else.I am very grateful for all these replies from you guys and I still suspect I am going to be a bit red faced when the eureka moment happens. Quote Link to comment Share on other sites More sharing options...
neil spencer Posted March 18, 2014 Author Share Posted March 18, 2014 I will try that after I have changed the coil again a bit later on today.Thanks.Neil. Quote Link to comment Share on other sites More sharing options...
DougBGT6 Posted March 18, 2014 Share Posted March 18, 2014 I'd test with a compression meter before taking off the head. More Important that all are around the same rather than a particular level, all around 150 or 140 or 130 etc is OK, but one at 150, one at 110, one at 130 etc. aint so good! Quote Link to comment Share on other sites More sharing options...
thescrapman Posted March 18, 2014 Share Posted March 18, 2014 Neildid you time it before you fitted the electronic ignition, or afterwards?CheersColin Quote Link to comment Share on other sites More sharing options...
andyfosters Posted March 18, 2014 Share Posted March 18, 2014 enough/any oil in the carb dampers? Quote Link to comment Share on other sites More sharing options...
neil spencer Posted March 18, 2014 Author Share Posted March 18, 2014 I tried timing again today and it is at around 9 degrees.Took battery off to change coil and fit new battery mat and of course that has turned in to a rust removal and paint exercise for the battery tray so won't be testing until tomorrow when paint is dry and I have roused from slumber after my night shift.Neil. Quote Link to comment Share on other sites More sharing options...
69vitesse Posted March 18, 2014 Share Posted March 18, 2014 Start the car in the dark and see if any of the leads are arcing.Had a real headache with the wifes old VW, when it got hot, splutter and hesitate. Home, check it over, all fine, off she'd go, after a while, cough, splutter.Insulation was breaking down in one of the leads when it got hot. Quote Link to comment Share on other sites More sharing options...
Richard B Posted March 18, 2014 Share Posted March 18, 2014 Steph's Dolomite was running like a dog, and would not want to start.Finally tracked it down to a fractured lug on the coil for the Lucas spade connector. Only sussed this when it finally gave up the ghost and broke off. Aghhhh! :B Quote Link to comment Share on other sites More sharing options...
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