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+--- Thread: auto advance Lucas distributor springs (/showthread.php?tid=1353)
auto advance Lucas distributor springs - JonE - 18-06-2018
Somewhere on the old forum I read about someone who found Morris Minor series 2 springs good for the advance weight mechanism
I've just fitted some NOS lucas springs to a DK4A and there is slack before the springs start to hold the lead weights in check .. i.e. until they are about 4/5mm apart. Is this normal, or are these springs perhaps wrong? I'm thinking that if they dont retract to touching in the centre, then they can't be right... although they do look exactly like whats come off, but a bit more tight!
I also wondered what the purpose of the second hole in the little brass pivot retainer is for. Does that give an adjustment (i.e. using the one a bit further away) if springs get worn?
What other sources of springs have people utlised, other than Distributor Doctor?
RE: auto advance Lucas distributor springs - Chris KC - 18-06-2018
Jon, I can't answer whether you have the 'right' springs but I do know some advance springs are deliberately 'slack' to give the desired characteristics.
RE: auto advance Lucas distributor springs - Ian Williams - 19-06-2018
Jon, I have obtained the best result using two differing weight springs, a light spring controls the initial advance and the heavy spring takes over as the revs build, as Chris quite rightly points out the heavy spring needs some slack to allow the light spring to do its job. If you use two heavy springs with slack on both you will effectively lose a portion of your advance at tickover, careful examination will show wear on advance weight and cam quadrant the pins as well as the bores of the little brass spring anchors and this needs to be eliminated. I would hazard that the majority of sevens on the road today are running constantly at almost full advance, hence my comments on the other thread, get it to work as intended and feel the punch in your back from all the raw power you unleash!!!
RE: auto advance Lucas distributor springs - Chris KC - 19-06-2018
(19-06-2018, 04:20 AM)Ian Williams Wrote: Jon, I have obtained the best result using two differing weight springs, a light spring controls the initial advance and the heavy spring takes over as the revs build, as Chris quite rightly points out the heavy spring needs some slack to allow the light spring to do its job. If you use two heavy springs with slack on both you will effectively lose a portion of your advance at tickover, careful examination will show wear on advance weight and cam quadrant the pins as well as the bores of the little brass spring anchors and this needs to be eliminated. I would hazard that the majority of sevens on the road today are running constantly at almost full advance, hence my comments on the other thread, get it to work as intended and feel the punch in your back from all the raw power you unleash!!!
You explained that much better than I did Ian!!
Must admit this job is on my 'to do' list - where did you get those NOS springs Jon?
RE: auto advance Lucas distributor springs - JonE - 19-06-2018
Thanks all.
Chris - a lucky find on ebay! (I may sell one of them now to fund buying an original Grasshopper, or perhaps swap for a Nippy crankcase and cash?)
https://www.ebay.co.uk/itm/5-PIECE-DISTRIBUTOR-ADVANCE-SPRING-SET-FOR-LUCAS-DISTRIBUTORS-TT1903/142808227000?epid=713733157&hash=item2140089cb8:g:nLcAAOSwEYBaZfFB
these are the items that came up when I googled Morris Minor mk2 advance springs. Ian - would some of these things give the early advance required? Indeed, they may, within them, have the charactersitics for the heavy ones too...?
I'm also presuming I should, whatever happens, be able to actuate the full advance manually by moving the rotor arm.. and that from what you have said, coming back to the weights are touching in the middle may not be required?
At present, even if I change one for a lighter spring to do the initial, the other is not going to 'return' that last few mm.
RE: auto advance Lucas distributor springs - Chris KC - 19-06-2018
I'd say not overpriced Jon IF they do the trick...
Just a thought but don't the Accuspark units have similar bob weights and springs? In which case these would presumably be tuned to the 'correct' advance curve for a Seven?
RE: auto advance Lucas distributor springs - Ian Williams - 19-06-2018
Jon, I would suggest the spring set would give you a good selection of spring weights to experiment with. As you would when setting up a carb find a nice long quiet stretch of road and do some timed acceleration tests over a fixed distance, but eliminate the wear first otherwise you are wasting your time! You will also find the best point for maximum advance in a similar way, measurable timed runs rather than subjective, oh that feels better.
RE: auto advance Lucas distributor springs - jansens - 19-06-2018
This is what the inside of mine looks like:
RE: auto advance Lucas distributor springs - Ian Williams - 19-06-2018
It looks like they have a conventional lobed cam, if this is accurate then a points base plate could be fitted and we would get a genuine comparison of the two systems on the same distributor with no other changes, worth the experiment if feel. Accuspark could market the unit in standard form for those who do not want to go electronic, now that is something worth considering, I think the only issue could be life expectancy but if the price was right one could accept a more limited life than the Lucas original.
RE: auto advance Lucas distributor springs - JonE - 19-06-2018
It's worth adding here that if you factor in the discount for those with a code, if you take off the 40-50 quid for the electronic kit which is sold separately, then a spare distributor - or spares for distributors - are plentiful, for not that much money... especially when you see the cost of the little springs alone when you need to get hold of them.
We do have to think about what is realistic in what we are discussing. If we had remanufactured units to Austin quality in this day and age, they would surely be 350-400 quid?