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RobH last won the day on July 8

RobH had the most liked content!

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About RobH

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  • Location
    Newbury, Berkshire
  • Cars Owned:
    MG M type
    ex- AH Sprite
    ex- Saab 900turbo
    ex- an assortment of 'grey porridge'

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  1. Andy, I found this info on tuning distributors (link below) which says the stronger (secondary) spring should be loose. Quote: Because the primary spring is in control of the lower end of the advance curve, it must be in tension under static conditions. The secondary spring must be loose to allow the primary spring to work and produce the characteristic advance curve with two different rates of advance as shown. Perhaps 'nipping them up' as you suggest is not a good idea? http://mgaguru.com/mgtech/ignition/pdf/tuning_lucas_dist.pdf
  2. +1. There's no use in putting electronic ignition on a worn distributor hoping it will fix things. It still uses the mechanical weights and springs and the vacuum advance, so those have to be working properly before you start.
  3. Yes that's right. Each graduation on the shaft by the diaphragm housing represents 4 degrees of advance.
  4. The distributor weights and springs determine the basic advance at any given engine speed. The vacuum advance unit provides additional advance beyond that if the throttle is at a low opening. The additional advance is lost when you open the throttle wide but it only reduces to that amount of advance set by the weights. It does not 'retard' below that. The distributor position should be set without the vacuum pipe connected anyway, so losing the pipe does not require any adjustment of the timing. There are retard units which do what you say but those are mounted on the other side of the distributor.
  5. I guess he is saying that because when you are looking at a quickly varying voltage a digital meter shows just a blur of numbers. Much easier to watch movement on a needle.
  6. A challenge! Well the main trick would be in getting a signal proportional to road speed. The easy way is to buy a pulse generator that fits between the speedo cable and the speedo (at a price!). https://transmissioncenter.net/shop/54mg-eight-pulse-signal-generator-for-your-electronic-speedometer-head/ If the cost of the pulse unit it is a problem then a cheap crank position sensor looking at a rotating component - perhaps a brake drum flange with a hole in it would do, though there's more work in getting that going. It's fairly simple to make a circuit that will switch on a relay if the pulse rate drops below some threshold value.
  7. Mine does that if the petrol is old, so perhaps something to do with poor vapourisation until the carbs and manifold get properly warm. As you say, it goes away as the engine warms up.
  8. Only if you lean on it !
  9. Well effectively that is what the filler neck on the sidescreen cars does Pete, and why it throws water out if you overfill it. Perhaps the modern bottle system was cheaper than a special radiator !
  10. Not on the early cars I think John. I believe they work the other way round. Your description is right for a meter with bimetallic operation, maybe not for the moving-magnet meters in 2s and 3s. ? This link is from the dark side but the info on troubleshooting is good: http://www.mgaguru.com/mgtech/electric/fg104.htm
  11. For a TR3A the sender resistance is 70 Ohms when full and zero when empty, according to this site: https://www.britishcarforum.com/bcf/showthread.php?33663-fuel-gauge-sender-TR3A
  12. The ONLY time it makes a difference is in cruising where the throttle is only partially open. It does next to nothing when you are pressing on. The idea is to advance the timing during cruise to get better mileage. I think you may find there is a metal olive on the end of the tube. That squashes down onto the tube to make a seal so you may not be able to feed any slack through. As James says, if you leave it you need to plug the carb end of the tube else the air drawn in will be weakening the mixture.
  13. RobH


    The type (25D/45D) is just the basic style. The advance curves are something else and will vary depending on the engine the dizzy was intended for. There were even different advance curves for the DM2 and 25D for the TR4 depending on the engine so it's unlikely a 45D from another car will be right:
  14. There is a company in Lincoln called Vehicle Electrix who own the site 'vehicleelctrix .co.uk' but they do electrical repairs and don't appear to sell cars. Nothing listed in Ipswich under that name.
  15. Probably just a fatigue failure of the joint due to old age. Too many thermal cycles. It can happen with any type of fuse, not just these ones.
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