Mad.ideas Posted May 10, 2020 Share Posted May 10, 2020 Hi All, Hope everyone is staying safe and well. I was hoping someone could help. For my sins I'm trying to get a Mk1 432 running which suffers from all four horseman of mechanical apocalypse (being old, british, petrol, and neglected), last running about 2 years ago after replacement contactors, would start (with a bit of difficulty) idle ok, but point blank refused to accelerate. Fast forward to the last few days, points, rotor arm and contactors cleaned, old fuel drained (complete system as best I could), new fuel chucked in, fuel system bleed (again as best I could), couple of plugs pulled and checked for spark (plugs seem ok, as does the spark), pump ticks away and seems to provide pressure, lines from the carb to the dizzy connected, disconnected, crossed and generally played about with, and today I pulled the carb off and stripped it down to check for blocked jets, varnished up floats/chambers or anything obvious but all seems normal, it seems to try and start and will occasionally catch but wont sustain and dies off again, occasional backfire and seems to try a bit harder while the throttle is being pumped but still wont run, i'm suspecting timing or ignition in some way shape or form, dizzy hasn't been removed (only split to clean everything up) it ran reasonably about 7 years ago and hasn't been messed with by anyone but me in the mean time. For those who know the B81 (I don't, but i'm picking up bits slowly!) it appears to my slight untrained eye to have a fixed dizzy cap so unless i'm mistaken no adjustment there... Anyone any ideas? Thanks Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted May 10, 2020 Share Posted May 10, 2020 2 hours ago, Mad.ideas said: For those who know the B81 (I don't, but i'm picking up bits slowly!) it appears to my slight untrained eye to have a fixed dizzy cap so unless i'm mistaken no adjustment there... Anyone any ideas? Thanks The distributor body does move to adjust timing, it has a limited arc of movement where it is attached to the cyl. block, two hex head screws, just release, from memory, I think if you turn it anti clock that is advancing the ignition. Quote Link to comment Share on other sites More sharing options...
Mad.ideas Posted May 10, 2020 Author Share Posted May 10, 2020 Excellent! hadn't spotted that even with my head and half my body stuck through the kidney hatch! 🤦♂️Will give that go 🤞🤞 Quote Link to comment Share on other sites More sharing options...
mtskull Posted May 10, 2020 Share Posted May 10, 2020 (edited) Having experienced a steep learning curve myself with RR B series engines over the last couple of years (and benefitted from some excellent advice via this forum), may I suggest the following: 1. Get ALL the plugs out and replace (or at least make sure they are thoroughly clean). 2. Replace the carburettor diaphragms as a matter of course. They are the devil’s own invention and you would not believe how badly these engines run when the diaphragms are not in tip-top condition. It would not surprise me if this turned out to be the whole and entire source of the problem. 3. Replace condensor(s). Other things to consider: Were the points correctly set up with a dwell meter when they were changed? You are probably best off leaving the ignition timing alone; if incorrect it might cause loss of power but is unlikely to be causing such profound symptoms as you describe. Good luck Andy Edited May 10, 2020 by mtskull Quote Link to comment Share on other sites More sharing options...
Mad.ideas Posted May 10, 2020 Author Share Posted May 10, 2020 Hi Andy, Great bunch of very knowledgeable and helpful people here! picked up a lot of useful and interesting bits lurking. Ill definitely have another look at the plugs, had them all out a couple of years back but another clean an test cant hurt Any recommendations of a source for diaphragms and condensers? Re the points I have to admit being of the younger generation and also more familiar with gas turbine engines (as well as being away for work at that time) my old man did the points, so I suspect not. Thanks Sam 9 minutes ago, mtskull said: Having experienced a steep learning curve myself with RR B series engines over the last couple of years (and benefitted from some excellent advice via this forum), may I suggest the following: 1. Get ALL the plugs out and replace (or at least make sure they are thoroughly clean). 2. Replace the carburettor diaphragms as a matter of course. They are the devil’s own invention and you would not believe how badly these engines run when the diaphragms are not in tip-top condition. It would not surprise me if this turned out to be the whole and entire source of the problem. 3. Replace condensor(s). Other things to consider: Were the points correctly set up with a dwell meter when they were changed? You are probably best off leaving the ignition timing alone; if incorrect it might cause loss of power but is unlikely to be causing such profound symptoms as you describe. Good luck Andy Quote Link to comment Share on other sites More sharing options...
jpsmit Posted May 11, 2020 Share Posted May 11, 2020 I can't help with what it is but it probably isn't the timing. If it was running 7 years ago and if no one has touched it since, it seems more likely fuel system or electrical. Timing doesn't just change nor carb settings. Can you run it off a can of gas with a hose? then you have cut out the fuel system all together Quote Link to comment Share on other sites More sharing options...
jpsmit Posted May 11, 2020 Share Posted May 11, 2020 Interestingly I just went to the opposite end of the spectrum - my Austin 7 forum and there is a thread about restarting cars after a wait. - he identified plugs. This is what it said: "I have experienced no problem with six month old petrol, but I did have a problem with a car that had been inactive for eighteen months. It would start up easily enough, and idle smoothly, but at anything more than a light throttle under load it would misfire and die. I initially thought it was dirt in the system, and thoroughly cleaned everywhere without any improvement. I then turned my attention to the electrics, and suspected the condenser; since it is a rare car in the UK I consulted the Green Spark Plug Company for advice and Tim Green immediately diagnosed stale fuel, and suggested a cure was a new set of spark plugs. I doubted the diagnosis, but tried the solution anyway, and with fresh petrol and the new plugs have experienced no further problems. Tim said that the rich mixture of stale fuel on start-up coats the plugs with a varnish which does not respond to any normal means of removal (although he did say that someone had suggested domestic oven cleaner - neither he nor I have tried it so cannot comment further on that idea)." 1 Quote Link to comment Share on other sites More sharing options...
ianevans Posted May 13, 2020 Share Posted May 13, 2020 Hi I would also suspect carb diaphrams also the ballast resistor and main HT lead Quote Link to comment Share on other sites More sharing options...
mtskull Posted May 13, 2020 Share Posted May 13, 2020 On 5/10/2020 at 9:54 PM, Mad.ideas said: Any recommendations of a source for diaphragms and condensers? Banister’s: https://www.milweb.net/go/banister/ I have always found them very helpful and are the “go to” people for all things B series. Quote Link to comment Share on other sites More sharing options...
Mad.ideas Posted May 13, 2020 Author Share Posted May 13, 2020 Hi all, sorry for the lack of replies, been attempting to slog through with what i've got, but no real progress to report until today. Thanks for all the suggestions! 24 minutes ago, mtskull said: Banister’s: https://www.milweb.net/go/banister/ mtskull, thanks for the pointer! I had tried Marcus glenn, but alas out of stock so ill try banister's I've reassembled and re-installed the carb, pulled and cleaned the plugs (they looks to be ok but never hurts to clean) once I cleaned the plugs I checked them only to find 1,2,3 and 5 only sparking intermittently!!! (I swapped the plugs just to check them out) Re-did the gaps on the point (19-21 thou from what I could find on the internet), still no real improvement so I thoroughly cleaned the old ones which I had saved luckily put those back in and reset the gap, all plugs seem to spark as they should. reassemble everything gave it a go and it fired!! not for long, didnt seem to want to sustain and with a couple of spectacular backfires from the disconnected air inlet, but progress none the less! pretty sure I've ran out of fuel, so ill get some more tomorrow when I do the weekly shop and see what happens. I'll still change the diaphragms, and condenser but hopefully I can coax it into life in the mean time! Will keep you all updated Thanks again! Sam 1 Quote Link to comment Share on other sites More sharing options...
fv1609 Posted May 13, 2020 Share Posted May 13, 2020 Sam do not buy an official B Series condenser. Even unused it will be quite old & will have deteriorated internally. Even years ago I remember people paying around £50 for the "proper condenser" an utter waste of money. Use any new 0.2mfd distributor condenser that will fit inside. You must use a distributor condenser as it will be rated at 500v, do not use 0.2mfd condenser other than one designed for a distributor. 1 Quote Link to comment Share on other sites More sharing options...
Mad.ideas Posted May 13, 2020 Author Share Posted May 13, 2020 Hi Clive thanks for the advice, I would not have thought about that! It sadly seems to be a common theme with MV spares, that NOS isn't always the superior option, can be a bit of a mine field weighing up the pros cons. I have a couple of m151 Mutt projects (an A1, A2 & m825) and seen several debates about on the facebook group about NOS and modern reproduction parts. Great gen and always appreciated! Thanks Sam Quote Link to comment Share on other sites More sharing options...
attleej Posted May 14, 2020 Share Posted May 14, 2020 Dear Sam, Further to Clive's advice I had a problem with a B81 in my Leyland Martian recovery on exercise in BAOR. The exhaust manifold gasket had failed and flames were overheating the distributor. It was so bad that the solder on the condenser melted! To get around this I used a Landrover condenser mounted on the air cleaner and connected with a bit of wire. It worked fine. Then the points pivots started to seize if I worked the engine too hard! Obviously I tried to make shielding to protect the dizzy from heat. Personally, I think that the most important thing is for the condenser to be designed for a 12 or 24 Volt system, be of new manufacture and good quality. Like Clive, I don't think it matters which one is used. I would put a cupful of petrol straight down the carb and try to start it with throttle wide open. When the mixture becomes right it should run quite well for a very short while (seconds). If it does nothing, you obviously have an ignition problem. Fire extinguisher! Like others, I would not touch the timing. I would put my money on the carb diaphragms as I have similar problems with the 'J60' on the Conqueror, ie very poor starting etc. John Quote Link to comment Share on other sites More sharing options...
fv1609 Posted May 14, 2020 Share Posted May 14, 2020 John wow melted solder that was getting hot! Picking up on your point about a newly manufactured good quality condenser, I agree but it doesn't matter whether the condenser was intended for a 6v, 12v or 24v system. I just use condensers for a car (ie 12v) in 24v systems. It doesn't matter what the voltage is of the LT energising the coil, it is the Back EMF that comes from collapse of the magnetic field when the LT is turned off (ie points open) that counts. This is typically 300v so condensers for distributors will usually be rated for 500v although they rarely state that! If you see any sparks as the CB opens that is the 300v, it is not the LT supply. I've met a lot of people over the years who have wasted good money on "24v condensers" when a normal car one will do provided you find one of a similar size & clamp configuration. Because of the high ratio of secondary coil turns to primary turns, the Back EMF on the secondary is much higher than on the primary. Provided the coil is one designed for the earth system of your vehicle then this 300v will be of the correct polarity & be added to your HT. If you have vehicle where the earth polarity was changed & someone has just swapped over the coil LT connections then this 300v will be of the wrong polarity & detract from the overall HT output. Using a coil of the wrong polarity for your earth system means your HT system is 600v worse off than using the correct polarity coil. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.