Classic cars forum & vehicle restoration.
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Ralphg
Joined: 06 Oct 2014 Posts: 30 Location: Clarens Free State South Africa
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Posted: Thu Jan 14, 2016 2:59 pm Post subject: Morris 8 Series "E" engine |
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Hi all, I took my car out for the first time after working on it for two years, it had not been on the road for some 30 years. The car surges badly under load and I wonder if anyone can help. New plugs and leads have been fitted and I've removed the electronic ignition and reverted back to original condenser. The carn & Pump have been overhauled. Help please. Ralph. |
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ukdave2002
Joined: 23 Nov 2007 Posts: 4104 Location: South Cheshire
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Posted: Thu Jan 14, 2016 4:40 pm Post subject: |
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Do you actually mean "surges" under load ? I suspect what you may be describing is a kangaroo type movement? which is nearly always intermittent fuel starvation, could be some dirt in the carb jet, badly centred carb jet, sticky carb damper, wrong oil in carb damper, sticky float chamber valve, dirt in a fuel line filter, vacuum in the fuel tank, problem with the fuel pump....
Dave |
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Ralphg
Joined: 06 Oct 2014 Posts: 30 Location: Clarens Free State South Africa
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Posted: Fri Jan 15, 2016 7:04 am Post subject: Morris 8 Series "E" engine |
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Hi Dave, yes "kangaroo" movement, I've overhauled both the carb & pump checked the float level and there's plenty of pressure from the pump. I'll recheck the float valve and the pump filter and see what happens. Many thanks. Getting anything 6 Volt here is a major problem. Ralph. |
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ukdave2002
Joined: 23 Nov 2007 Posts: 4104 Location: South Cheshire
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Posted: Fri Jan 15, 2016 8:44 am Post subject: Re: Morris 8 Series "E" engine |
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Ralphg wrote: | Getting anything 6 Volt here is a major problem. Ralph. |
Hi Ralph
If you are a Morris Register member, you can take advantage of the spares service, that now has an online shop and ships world wide.
Cheers
Dave |
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goneps
Joined: 18 Jun 2013 Posts: 601 Location: Auckland, New Zealand
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Posted: Fri Jan 15, 2016 10:56 pm Post subject: |
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Ralph,
Does this happen all the time, or only after restarting a hot engine? On unleaded fuels the M8 can be susceptible to fuel vaporisation after a hot start, or even while driving under heavy load in hot conditions. Considering that it's the middle of summer for those of us in the southern hemisphere...
Richard |
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Ralphg
Joined: 06 Oct 2014 Posts: 30 Location: Clarens Free State South Africa
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Posted: Sat Feb 13, 2016 10:27 am Post subject: Morris 8 Series "E" Engne |
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Hi Richard, Sorry for the delay in replying, I don't think its particularly engine related as I've been tinkering round that and the engine runs fine, hot or cold, have overhauled the pump again but that's not the problem. I have now found that the front springs are solid and may be the cause of the hopping especially on our gravel roads??. Ralph. |
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goneps
Joined: 18 Jun 2013 Posts: 601 Location: Auckland, New Zealand
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Posted: Sat Feb 13, 2016 1:42 pm Post subject: |
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Well, Ralph, we're really working blindfold here. I think you need to describe the symptoms in a much more detailed and unambiguous way. We're anxious to help, but it's hard enough to diagnose faults from a distance even with clear and accurate information. Originally you appeared to be saying that engine is cutting out intermittently—is it, or isn't it?
I don't understand how the front springs can be "solid" unless the original suspension dampers have been replaced with different units that are themselves either seized or much too hard. The latter is often the case when telescopic units are substituted on such a lightweight car.
My Tourer and I used to be in South Africa (Pietermaritzburg) so I'm quite familiar with gravel roads, and they're by no means uncommon in New Zealand and Australia. The car should ride acceptably regardless of sealed or unsealed surfaces.
Richard |
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Ralphg
Joined: 06 Oct 2014 Posts: 30 Location: Clarens Free State South Africa
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Posted: Wed Feb 17, 2016 9:53 am Post subject: |
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Hi Richard, Sorry to be seem to be going round in circles, the only way I can describe the problem is surging or "kangaroo hop". I did think that the piston was fluttering but having checked the oil in the damper and ensuring that the piston was free, I'm at a loss as to what the problem is. The front springs seem to be quite hard and this may be from the telescopic shocks that have been fitted as they may be too hard for this application. Ralph. |
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goneps
Joined: 18 Jun 2013 Posts: 601 Location: Auckland, New Zealand
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Posted: Wed Feb 17, 2016 11:54 pm Post subject: |
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Ralph,
We need to know under what circumstances the surging occurs. Describe exactly what you have to do to make it happen; eg. engine hot/cold, accelerating or on steady throttle, at what speed, which gear, etc., etc. There cannot be too much or too detailed information if we're to get to the bottom of this.
As regards the suspension, try driving the car without the telescopic dampers. Leaf springs have quite a lot of inherent damping from the friction between the leaves. It will be a bit 'bouncy', but should be quite controllable; don't try racing around bumpy corners in this condition, though.
The original Armstrong pear-shaped dampers give only a modest damping effect, and there is less damping on the bump (upward) stroke than the rebound (downward). This is exactly what a small car with leaf springs needs, whereas most telescopic units seem to offer equal resistance in both directions and nearly all are too firm anyway. The only telescopics that seem to work reasonably well on a Morris 8 are those for the original Mini.
Richard |
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ka
Joined: 03 Dec 2007 Posts: 600 Location: Orkney.
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Posted: Thu Feb 18, 2016 8:36 am Post subject: |
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Do you have a friend or colleague you can let drive the car, or at least sit with you to be able to diagnose the issue that has at least a wiff of mechanical knowledge? _________________ KA
Better three than four. |
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Ralphg
Joined: 06 Oct 2014 Posts: 30 Location: Clarens Free State South Africa
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Posted: Thu Feb 18, 2016 9:22 am Post subject: |
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Hi Richard, Driving with a steady throttle, the surging occurs at all speeds and gears although I've not got beyond about 30 mph as yet. I normally allow the engine to warm up a bit before I drive off so although it may not be at optimal temperature, it is not cold. I still suspect that it is fuel related and as I've said, I've overhauled the pump with the help of Brian in the Uk who sent me detailed instructions on the SU Pump and how to correctly set it up. The needle & seat have been checked for correct setting as has the needle. The only thing I've not done so far is to drive with the petrol cap removed to see if there is any vacuum there that has any effect. I take your point about the shocks and will remove them and see what happens. Hope this adds to what I've already said. To KA, I've rebuilt and restored 5 vintage & old motor bikes (one to concourse) and 4 vintage and old cars over the years so have some mechanical knowledge. Ralph. |
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goneps
Joined: 18 Jun 2013 Posts: 601 Location: Auckland, New Zealand
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Posted: Thu Feb 18, 2016 1:02 pm Post subject: |
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Ralph,
Good thought about driving with the fuel cap off—try that and see what happens. Does the surging occur constantly, or only intermittently? What effect does applying half choke have? Does it improve with more throttle or less, or make no difference? Surely you've tried these standard measures?
How long does a surge cycle last—a second off and then on again, or longer? Does it jerk your neck, or is it more subtle?
It's unlikely to be the fuel pump; that will usually stop working altogether and the engine will then run for 15 or 20 seconds until the float chamber is empty, then stall. You should be able to check whether it's working by watching the ammeter needle, which will flick towards the discharge side every time it cycles.
If it's happening with an engine that's only warm then it's not vaporisation, which will usually occur after a hot restart.
Another thing you could try is to remove the cap with damper from the carburettor dashpot. Earlier models of SU worked perfectly well with no damper, so it's not essential. Use only very thin oil in it, such as 3-in-1 or sewing machine oil.
Has the jet been correctly centred, so that the piston drops with a click when lifted with a finger and released? Remove the damper before testing this.
Do you know what jet needle is fitted? What fuel are you using? 91 unleaded is all that's needed. How old is the fuel in the tank? Have you tried draining and refilling it with fresh fuel?
Richard |
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Rick Site Admin
Joined: 27 Apr 2005 Posts: 22438 Location: UK
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Bitumen Boy
Joined: 26 Jan 2012 Posts: 1735 Location: Above the snow line in old Monmouthshire
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Posted: Thu Feb 18, 2016 2:42 pm Post subject: |
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Rick wrote: | It's not something simple like the points closing up, that's causing problems? or perhaps the shaft in the dizzy spinning slightly out of true?
RJ |
Or, perchance, a duff old - or new aftermarket - condenser? Problems with those can feel awfully like fuel problems at times. |
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Rick Site Admin
Joined: 27 Apr 2005 Posts: 22438 Location: UK
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Posted: Thu Feb 18, 2016 3:20 pm Post subject: |
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Bitumen Boy wrote: | Rick wrote: | It's not something simple like the points closing up, that's causing problems? or perhaps the shaft in the dizzy spinning slightly out of true?
RJ |
Or, perchance, a duff old - or new aftermarket - condenser? Problems with those can feel awfully like fuel problems at times. |
I had a problem recently with a newly-purchased rotor arm. After a very very short period of running, the rivet began to wear, allowing the brass contact on the arm to move inwards and outwards slightly when spinning, randomly opening and closing the gaps to the contacts in the cap.
RJ _________________ Rick - Admin
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