| Author | Message | ||
     John Grieve Experienced User Username: john116 Post Number: 19 Registered: 4-2012 |
I have recently done a top end rebuild and cannot get the engine to run smoothly. It sounds like it is misfiring and a fair amount of water is coming out the exhaust. I never really ran the engine before the rebuild so I don't know if the problem is new or pre-existing. The problem appears to be on the A-side carburettor and the cylinders it feeds. Using a Gunson Colortune I cannot get a nice blue flame and the mixture screw seems largely ineffective. They are newly rebuilt carburettors, new spark plugs, new spark plug leads and ignition coil. I have checked there is a strong spark at each lead. I have disconnected all vacuum connections and tried as best I can to check for air leaks downstream of the carburettor. I have also done a compression check on two of the four cylinders the A-side carburettor feeds (I can't get the gauge to the other two). | ||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 1161 Registered: 6-2006 |
Is the fuel new and free from water? If you look at the jets are they moving up and down when adjusting them? Put right the way up so flush with the top then 1.5 turns down. Can you see the fuel level down the jet? Throttles synchronised? Did you block the vacuum hoses? Triple checked the firing order? Leads and cap OK? | ||
| John Grieve Experienced User Username: john116 Post Number: 20 Registered: 4-2012 |
Hi Paul, Thanks for your reply and advice. Yes the fuel is new and I have triple checked the spark plug leads to ensure correct firing order. The leads and distributor cap are new. I set the jets to the factory preset (3.05mm below the bridge) initially, also set the needle valve floats as per the manual. The jets do move up and down when adjusting the mixture screw and I can just see fuel down through the jet. I can get the Colortune to show a rich mixture if I wind the jet a LONG way down (e.g. 4-5 turns), which doesn't seem right. Also can't then get a nice blue flame or smooth running when I back it off. I have synchronised the throttles and I disconnected all vacuum hoses (main vacuum take-off, choke stove pipe, ported vacuum and transmission vacuum modulator). The B side carburettor and cylinders it feeds are running beautifully, it's the A-side that is giving me trouble. If you have any further thoughts that would be great. Thanks so much again for your advice. John | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 357 Registered: 5-2012 |
John I would re-visit the synchronisation of the throttles unless you are really sure they are correct. I bought a Unisyn Carbalancer for around 30 bucks and find it invaluable in checking the synchronisation of the carbs. I mention this as I had the same problem on SRX18501 and found, on using the carbalancer, that all the work was being done by the B bank. Geoff. | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 881 Registered: 9-2004 |
Remember that balancing of one carb does two cylinders on each bank. Did the engine have rough consistant running before the top end was overhauled. The electronic distributor if failing can also give these symtoms. would first do a cylinder leak test to clear up other points not mentioned as yet. | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 358 Registered: 5-2012 |
Patrick I clean forgot about that. When I was using my colortune I had selected the correct cylinder on each bank, but since it was a while ago I forgot to mention the two pots per bank. It occurs to me we could configure our cars to run in economy mode for motorway cruising by shutting off the fuel to the one carb. Great idea? No, thought not. Geoff | ||
| richard george yeaman Prolific User Username: richyrich Post Number: 149 Registered: 4-2012 |
Hi all. It would be very helpful in this instance to myself and others to know which of these cylinders is operated by which carburettor. Richard. | ||
| John Grieve Experienced User Username: john116 Post Number: 21 Registered: 4-2012 |
In terms of which carburettor feeds which cylinders, this is as follows: A bank side carb feeds cylinders: A1, B2, B3, A4. B bank side carb feeds cylinders: B1, A2, A3, B4. | ||
| John Grieve Experienced User Username: john116 Post Number: 22 Registered: 4-2012 |
It wasn't run for long before being rebuilt. That was over 2 years ago now. It wasn't as rough as it is now, but by no means smooth either. Have done a test on two cylinders which are OK, but will do the other two. How does the electronic distributor components fail? And what is a good replacement to use? Thanks everyone for your suggestions. | ||
| Carl Heydon Frequent User Username: car Post Number: 62 Registered: 2-2004 |
Have you checked for an intake leak? | ||
| Chris Browne Prolific User Username: chrisb Post Number: 133 Registered: 2-2010 |
John, I'm not sure what fails in the electronics of the distributor but fail they do! I had an issue last summer with my 1979 Shadow 2 when the engine would suddenly cut out. This could be when the engine was cold, warm, hot, when the car was stationary or on the move. It was totally unpredictable and the engine just cut out without warning. Clearly, this was not ideal, especially if you are in traffic in town as, apart from everything else, you lose the power steering. What was even more infuriating was that after the engine cut out, it would usually start again straight away and run normally until it cut out again. The fault was spoiling my enjoyment of the car as I could not rely on it keeping going. I took advice from a Shadow expert and was told it was most likely to be an ignition problem. I bit the bullet and gathered together replacement plugs, leads, distributor cap, rotor arm, coil, ballast resistor and electronic module, all on a sale or return basis. The plan was to replace one item at a time until the fault went away. As luck would have it, I replaced the electronic module first and that immediately solved the problem. The engine has not cut out since I changed the module and I am happy again now I can rely on the car. I believe there are after market modules which will fit but I fitted a Lucas one, which has been updated since the original, incidentally. It was not cheap but it has given me peace of mind. Hope this helps. Kind regards, Chris | ||
| Mark Aldridge Prolific User Username: mark_aldridge Post Number: 126 Registered: 10-2008 |
Chris on my 1982 Spirit, the ignition module failure was due to the wires breaking inside the insulation , where they enter the module. this is due to the continual movement of the advance/retard.By removing the sealer from the module it was possible to solder new wires in,with difficulty.I have now converted to the Pertronix unit which uses a conventional coil and no Ballast resistor- seems fine.The loss of the ballast cold start has no effect. Mark | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 882 Registered: 9-2004 |
John the failing with the distributors are many. The first to check is the reluctor air gap that should be 8thou however I would do the leak down test first. This is not a compression test but more of a check on piston blow by,head gasket leak, cracked head,valve blow by, sticking inlet exhaust valves!. This is carried out with a whistle to find TDC then compressed regulated air one cylinder at a time. When TDC is found lock the engine and pressurise the cylinder doing each one in turn listening to the exhaust tail pipe, inlet manifold,oil filler cap removed,blow by from piston check and the radiator cap removed to check for air bubbles. If ok then check carbs etc with manometer and co tester. If all ok then check in more detail with rotor arm distributor timing etc. | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 359 Registered: 5-2012 |
Patrick I did not realise you could run a blow by test without sophisticated equipment. Obviously you need an air compressor. What is the method - what air pressure do you use and can you buy a line that screws into the spark plug hole. Could you use a tire inflating pump? Geoff. | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 883 Registered: 9-2004 |
Geoff in the UK you can get a DIY one here: http://www.ebay.co.uk/itm/Sealey-Cylinder-Leakage-Tester-2-Gauge-Cylinder-Leakage-Tester-Tool-DIY-/360802906053?pt=UK_Hand_Tools_Equipment&hash=item5401876fc5 In the States one may well cost under 100 bucks. A compressor will be needed but an electric tyre pump may do the job with a storage tank provided it does not overheat. | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 360 Registered: 5-2012 |
Patrick Many thanks for the info. Geoff | ||
| Mark Aldridge Prolific User Username: mark_aldridge Post Number: 127 Registered: 10-2008 |
http://www.ebay.co.uk/itm/Sealey-Compressed-Air-Adaptor-Use-with-VS160-Vehicle-Service-Tools-Engine-Cyli-/290771863742?pt=LH_DefaultDomain_3&hash=item43b35a88be#ht_0wt_0Geoff ,I have used this to pressurise cylinders Mark | ||
| John Grieve Experienced User Username: john116 Post Number: 23 Registered: 4-2012 |
Checked all 8 cylinders, compression all ok. | ||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 1162 Registered: 6-2006 |
have you checked air intake blend flap , distributor vac advance and gearbox modulator vacuum lines are all good and sealed if you suck on them? | ||
| John Grieve Experienced User Username: john116 Post Number: 24 Registered: 4-2012 |
Yes, checked all those too. Running out of things to check.... | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 361 Registered: 5-2012 |
Hi John I hope it's not this, but are you sure the valves are timed correctly. You said you did a top end rebuild which means you would have removed the camshafts. Are the camshaft and crankshaft timing gears meshed correctly to give the right valve timing. Geoff. | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 884 Registered: 9-2004 |
John what were the plugs like when taken out ie any sooted up? If ok could you start up the car and run for a short time and then check the fuel level in the float chamber on A side carburettor? Have known the float needle valve to have a blockage. How is the coil primary and secondary resistance oms? Ps a compresson test will not show up a cracked head or gasket failings! | ||
| John Grieve Experienced User Username: john116 Post Number: 25 Registered: 4-2012 |
No soot, looked all OK. Float chamber fuel levels all seem ok too after car running for a while. Haven't measured coil yet, although it is new (doesn't guarantee it's OK I know) | ||
| gordon le feuvre Experienced User Username: triumph Post Number: 26 Registered: 7-2012 |
When you overhauled carbs did you take off union on float lid to check gauze filter behind this to make sure not blocked? It is important that carbs are synchronised, i.e both butterflys are closed at idle and bypass volume screws set. As Paul Yorke has intimated, it does seem like a vacuum leak. The diagnosis does seem to be a weak mixture, is the jet set correctly in piston? | ||
| John Grieve Experienced User Username: john116 Post Number: 26 Registered: 4-2012 |
Gordon - thanks for the posting, will check all you mention this weekend. Updates to follow. | ||
| Jan Forrest Grand Master Username: got_one Post Number: 537 Registered: 1-2008 |
You say "I have recently done a top end rebuild" and "a fair amount of water is coming out the exhaust". Have you had the heads or inlet manifolds off? Is the coolant level dropping? If the answer to both is 'Yes' then I would be looking for a water leak into one or more cylinders. |
