cliff.b Posted August 15, 2021 Report Share Posted August 15, 2021 Just want to confirm that I should noticeably see the dizzy baseplate move if I suck on the vac tube? It isn't doing so, although I have lubricated everything & the vac operating rod is free to move. Assuming I should be seeing movement, is there anything else I can try doing to it? Link to comment Share on other sites More sharing options...
johny Posted August 15, 2021 Report Share Posted August 15, 2021 I take it you can rotate the backplate by hand quite easily? The sucking does take a bit of effort as you have to progressively pull vacuum through repeated sucks without letting it escape. If your not pulling air in, the pipe and diaphragm must be good (or blocked?) so difficult to see what else could be wrong... Link to comment Share on other sites More sharing options...
cliff.b Posted August 15, 2021 Author Report Share Posted August 15, 2021 5 minutes ago, johny said: I take it you can rotate the backplate by hand quite easily? The sucking does take a bit of effort as you have to progressively pull vacuum through repeated sucks without letting it escape. If your not pulling air in, the pipe and diaphragm must be good (or blocked?) so difficult to see what else could be wrong... Yes, the baseplate moved manually. Perhaps I'm not sucking hard enough 🤢 If it's the vac mechanism itself, can anything be done? Link to comment Share on other sites More sharing options...
johny Posted August 15, 2021 Report Share Posted August 15, 2021 well its just a diaphragm so if punctured wont operate the rod but then air will be sucked in to the pipe. I suppose the rod could have become detached from the diaphragm which would then give good vaccum but no operation - can you hear the resistance of the diaphragm being operated when you twist the backplate? You might even feel the slight pressure that generates at the end of the pipe... Link to comment Share on other sites More sharing options...
johny Posted August 15, 2021 Report Share Posted August 15, 2021 The sucking action is like that for a boiled sweet rather than a drinking straw... Link to comment Share on other sites More sharing options...
cliff.b Posted August 15, 2021 Author Report Share Posted August 15, 2021 9 minutes ago, johny said: well its just a diaphragm so if punctured wont operate the rod but then air will be sucked in to the pipe. I suppose the rod could have become detached from the diaphragm which would then give good vaccum but no operation - can you hear the resistance of the diaphragm being operated when you twist the backplate? You might even feel the slight pressure that generates at the end of the pipe... Many thanks. I will investigate further. Link to comment Share on other sites More sharing options...
chrishawley Posted August 15, 2021 Report Share Posted August 15, 2021 Needs a lot of suck. I use a 100ml syringe (and 2 ft plastic pipe to attach). Handy for testing on the bench but also handy for testing with the engine running when (with a strobe) one can observe the timing marks moving as one sucks. Not precise, but provides general confirmation the vac unit is functioning ok and not leaking down. Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 15, 2021 Report Share Posted August 15, 2021 yes pucker up and suck and a mouth full of oily petrol is normally found ...nice as said if you just get air the thing has a leak then its a replacement needed if the vac unit doesnt spring back the spring has failed it needs a replacement if all is well it will pull the rod and turn the base plate do make sure a long screw has not been fitted in the points as this can jam the top plate from moving this if a common fault Pete Link to comment Share on other sites More sharing options...
Andy Moss Posted August 15, 2021 Report Share Posted August 15, 2021 If you disconnect the vacuum unit from the dizzy (only 2 screws) and suck the end you should see the leaver that operates on the base plate gradually move towards you as you continue to suck. If it does not move or moves a couple of millimetres then is faulty. Should move 1/2” or more. Manual usually had spec for degrees of advance for a vacuum unit. Spit3 is around 10degs, yours might be similar. Cheers. 1 Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 16, 2021 Report Share Posted August 16, 2021 if its a lucas the numbers on the capsule ei like 7 -11-12 is the HG vac starts the vac it stops and the amount of advance it gives delco are not marked Pete Link to comment Share on other sites More sharing options...
Stratton Jimmer Posted August 16, 2021 Report Share Posted August 16, 2021 I concur with Chris that a 100ml syringe is ideal for the job. It produces a much greater degree of vacuum than the human gob can achieve. Link to comment Share on other sites More sharing options...
cliff.b Posted August 16, 2021 Author Report Share Posted August 16, 2021 Ok, after further investigation I have applied vacuum with a syringe and there is slight movement but no noticeable change in timing if I do this when looking with the strobe light. Also, although the timing does advance with increased revs it's not as much as I was expecting. I have found a reference for the advance curve of a spit 1500 which suggests the following and wondered if anyone can confirm this Link to comment Share on other sites More sharing options...
johny Posted August 16, 2021 Report Share Posted August 16, 2021 Sounds like your dizzy needs a complete overhaul to be sure its working as well as possible... Link to comment Share on other sites More sharing options...
cliff.b Posted August 16, 2021 Author Report Share Posted August 16, 2021 9 minutes ago, johny said: Sounds like your dizzy needs a complete overhaul to be sure its working as well as possible... Since I last posted I have dismantled further & the weights have 8 stamped on them which I believe means they give a max of 8 Deg distributor advance which would be 16 Deg at the crank. Add the 10deg static advance and that gives 26 Deg which I don't think is enough. Reading online suggests the weights should say 14 which would give a max crank advance of 38deg (14x2)+10 I would buy a replacement if certain I was getting the correct part but can't find any 45d dizzys specifying different advance curves or any availability of different weights. Just one generic for all applications. Link to comment Share on other sites More sharing options...
chrishawley Posted August 16, 2021 Report Share Posted August 16, 2021 Figures from the 1975 Triumph ops manual are; • static 10 degrees BTDC Additional centrifugal advance (crankshaft rpm and crankshaft advance) 600 - nil 1100 - 2 to 6 degrees 1400 - 6 to 10 degrees 2000 - 8 to 12 degrees 3200 - 12 to 16 degrees That's for a 45D4 distributor Lucas model 41449 The figures you have suggest a somewhat sharper advance curve. A thing maybe to check is whether those figures are from an American source. If so they may reflect the 1500 engine in its 'strangled' American iteration and not relate well to the UK configuration. Getting 'on spec' is good but much is determined by the driving experience as well. Link to comment Share on other sites More sharing options...
cliff.b Posted August 16, 2021 Author Report Share Posted August 16, 2021 12 minutes ago, chrishawley said: Figures from the 1975 Triumph ops manual are; • static 10 degrees BTDC Additional centrifugal advance (crankshaft rpm and crankshaft advance) 600 - nil 1100 - 2 to 6 degrees 1400 - 6 to 10 degrees 2000 - 8 to 12 degrees 3200 - 12 to 16 degrees That's for a 45D4 distributor Lucas model 41449 The figures you have suggest a somewhat sharper advance curve. A thing maybe to check is whether those figures are from an American source. If so they may reflect the 1500 engine in its 'strangled' American iteration and not relate well to the UK configuration. Getting 'on spec' is good but much is determined by the driving experience as well. Ok, that makes a lot more sense and would appear to reflects what I am actually seeing. I just need to sort out the vac advance now. Many thanks 👍 Link to comment Share on other sites More sharing options...
cliff.b Posted August 17, 2021 Author Report Share Posted August 17, 2021 22 hours ago, cliff.b said: Ok, that makes a lot more sense and would appear to reflects what I am actually seeing. I just need to sort out the vac advance now. Many thanks 👍 Removed the vac advance and even applying force in the garage I can't get the actuator to move more than a couple of mm. I am sourcing another one. Link to comment Share on other sites More sharing options...
daverclasper Posted August 18, 2021 Report Share Posted August 18, 2021 Distributor Doctor has many parts I think (not sure for Delco). Also does rebuilds, as do others Link to comment Share on other sites More sharing options...
cliff.b Posted August 19, 2021 Author Report Share Posted August 19, 2021 Bought a new vacuum advance unit for £8.50 from Powerspark Ignition and the car is transformed. Much livelier and can now get a consistent tickover👍 Many thanks for all advice offered. Link to comment Share on other sites More sharing options...
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