Steve Cureton Posted February 23, 2008 Share Posted February 23, 2008 My dizzy advance unit isn't working as there's no resistance if I suck on the pipe. The pipe is in good order so the unit itself must be scuppered. This is one of the few jobs I've never even looked at before, I presume it's just a matter of buying a replacement advance unit and swapping them over but any advice gratefully received as the Haynes manual is next to useless for this task. Link to comment Share on other sites More sharing options...
Nick Jones Posted February 23, 2008 Share Posted February 23, 2008 Steve,You don't say what car this is on - I presume your Vitesse. Physically it's very easy to swap. There is a little wire clip on the end of the threaded shaft that sticks through the external timing adjuster nut. Pop this off and unscrew the adjuster nut. Take care not to loose the little springclippy thing that gives the click effect. Under the cap, use a screwdriver to pop the loop off the peg on the points plate and you should be able to remove it. Refitting the reverse etc etc. Check ignition timing when complete.The hard part will be getting a replacement. Note that not all vac advance capsules are the same -they have different advance characteristics. the numbers are marked on the can.See http://www.teglerizer.com/mgstuff/advance_curves.htm for info on how to interpret them and what they should (probably) be.Note that the Vitesse has fairly aggressive characteristic which could be a disadvantage in that on my car at least it used to cause severe light throttle pinking on unleaded. I fitted a different one (can't remember what offhand but still have it somewhere so can look if you're interested). This means that spending ages hunting down exactly the right one is probably a waste of time!CheersNick Link to comment Share on other sites More sharing options...
Steve Cureton Posted February 24, 2008 Author Share Posted February 24, 2008 Thanks Nick, that's an excellent detailed reply and it sounds like an easy enough job. The car is a 1200 Herald but I expect the principle is the same, just got to find the right unit now. I have got a spare Herald awaiting restoration so I'll take a look if that's the got the right reference number (assuming it's working of course). I prefer to locate one from elsewher if I can as I don't want to end with a Herald in so many bits I can't rebuild it when the time comes.Steve Link to comment Share on other sites More sharing options...
Nick Jones Posted February 24, 2008 Share Posted February 24, 2008 Ah, 1200 Herald. Remember fitting a working vac advance to my Herald years ago when it was still 1200 and being amazed at the difference it made. So much more torque at part throttle! Well worth it!Nick Link to comment Share on other sites More sharing options...
Steve Cureton Posted February 24, 2008 Author Share Posted February 24, 2008 Just fitted the one off my spare engine and it has made a big difference as it now runs much smoother - I had a great 25 mile test drive through the Shropshire countryside. Thanks Link to comment Share on other sites More sharing options...
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