Davemate Posted April 4, 2015 Share Posted April 4, 2015 It was a standard 2ltr mk1 Now that a 2.5 is in place do I just replace all the feeds to coil and dizzy. Would the original system had a ballast resistor thing in place and will it stay there or do I have to remove it for the 2.5 or do I need to fit one Quote Link to comment Share on other sites More sharing options...
Nick Jones Posted April 4, 2015 Share Posted April 4, 2015 Don't think the 2000 Mk1 would have had a ballast resistor. The 2.5 might have done, depends where it came from. Simple solution, swap coil from 2000 :) Alternatively, measure the resistance of the primary winding on both coils (across two spade terminals). If they are the same, you can use either.Nick Quote Link to comment Share on other sites More sharing options...
Davemate Posted April 4, 2015 Author Share Posted April 4, 2015 I'm useing the 2000 coil but I wasn't sure if the 2.5 dizzy had anything that required the ballast thingy to be fitted,or not Quote Link to comment Share on other sites More sharing options...
piman Posted April 4, 2015 Share Posted April 4, 2015 Hello Dave, no it will all fit and match what you have.Alec Quote Link to comment Share on other sites More sharing options...
Davemate Posted April 4, 2015 Author Share Posted April 4, 2015 Cheers Alec Quote Link to comment Share on other sites More sharing options...
Tony68 Posted April 10, 2015 Share Posted April 10, 2015 I have a feeling the advance curve is not the same between 2000 MkI and 2500 engines (cam profiles are different - less overlap on the MkIs?) but probably neither are exactly right anyway for modern fuels, esp if you've done any tweaking to head or exhaust. I'm told most tuners reduce the total mechanical advance (the RR did for mine). I can recommend a rolling-road tuneup - from somebody who knows about these cars - *when* the engine is running okay to start with. Quote Link to comment Share on other sites More sharing options...
piman Posted April 10, 2015 Share Posted April 10, 2015 Hello Tony, there are many variations of distributors between the different 2500 engines, never mind between the 2000 and the 2500. I don't think the curve will be affected greatly by the fuel as that is determined by the internal combustion characteristics of the engine, although it may be advanced or retarded due to the fuel? An engine with poor combustion characteristics will end up needing a lot of total advance and vice versa.Alec Quote Link to comment Share on other sites More sharing options...
RobPearce Posted April 13, 2015 Share Posted April 13, 2015 piman wrote:I don't think the curve will be affected greatly by the fuel as that is determined by the internal combustion characteristics of the engine, although it may be advanced or retarded due to the fuel?The characteristics of the fuel make a HUGE difference! It's the fuel that is burning so of course the characteristics of the fuel make a big difference to the speed of burn, and to how much that's affected by in-cylinder pressure. These are the fundamental governing factors of ignition advance - not just the static value but the slope of all the adjustments (mechanical and vacuum advance). Quote Link to comment Share on other sites More sharing options...
dazzer Posted April 13, 2015 Share Posted April 13, 2015 Yep For the 2000 with high comp 11:1 and TR5 cam the dizzy is set at 13 deg max advance. Goes like stink and at that you can run it on 95 when supers not available and even under load not a sign of pinking. Quote Link to comment Share on other sites More sharing options...
piman Posted April 13, 2015 Share Posted April 13, 2015 Hello Rob, the burn speed is a factor but the physical engine characteristics are what determine the curve, if it was simply fuel rate all engines would have the same curve. That is why I said that the curve may need further or less advance depending on the fuel.Alec Quote Link to comment Share on other sites More sharing options...
RobPearce Posted April 14, 2015 Share Posted April 14, 2015 Alec,Nothing in what I wrote could possibly suggest I wasn't fully aware that the combustion chamber design is ALSO a very major factor. You seemed to think it was the only one, and that the fuel made no difference. If so, you were mistaken.Rob Quote Link to comment Share on other sites More sharing options...
piman Posted April 14, 2015 Share Posted April 14, 2015 Hello Rob, as I said in my first comment on the subject "although it may be advanced or retarded due to the fuel?"Alec Quote Link to comment Share on other sites More sharing options...
RobPearce Posted April 14, 2015 Share Posted April 14, 2015 OK, but if you agree that it will affect the advance, why did you say Quote:I don't think the curve will be affected greatly? If the fuel is affecting the burn rate (time) then it's definitely going to have a different amount of effect on advance (angle) at higher RPM than it does at idle. Quote Link to comment Share on other sites More sharing options...
piman Posted April 14, 2015 Share Posted April 14, 2015 Hello Rob, because it will still follow the basic burn characteristic of the engine, e.g. a P.I. will still require less advance than a TC for instance, The reason I made the comment in the first place is I hear all the time that as the fuel is different then the old curve is valueless, more or less, I still believe that it is a good basis to start from.Alec Quote Link to comment Share on other sites More sharing options...
RobPearce Posted April 15, 2015 Share Posted April 15, 2015 I'm not saying anything about different engines not being different, nor am I saying the original curve is "valueless".I think we're probably not really in disagreement. It's merely that you're fixated on not throwing out the baseline and it came across as "you don't need to change it", whereas I'm saying that if you need to change the base advance for any reason then you should consider the effects on the curves too. A fuel that burns fast enough to shift the idle advance from, say, 10BTDC to 6BTDC will almost certainly need the 40BTDC at higher speed to become less than 36BTDC - 25BTDC would be a more likely value. Quote Link to comment Share on other sites More sharing options...
Rod 2500S Posted April 17, 2015 Share Posted April 17, 2015 Hi GuysGiven that we have established that the advance curve will need to be changed for differing engines fuel etc, how do we go about this given the fixed mechanical nature of the original dizzy? e.g the centrifugal advance system.CheersRod Quote Link to comment Share on other sites More sharing options...
piman Posted April 17, 2015 Share Posted April 17, 2015 Hello Rod, whilst not entirely agreeing with your first statement, Lucas distributor total advance can quite easily be changed, either get a different rotor (There is a number stamped on the beak of the rotor in distributor advance degrees), or modify the existing rotor by filing or welding to increase and decrease advance respectively, alternatively a collar can be fitted to the stop pin to decrease advance. Different springs can be fitted but you really need a test rig to determine what the effect is? Also be aware that vacuum units have their own setting, look to see what numbers or on the side, they are minimum vacuum, maximum vacuum and advance at maximum vacuum in engine degrees advance (Twice distributor advance) You can only alter those by replacement. See here:- https://www.britishvacuumunit.com/The hardest part is actually evaluating the effect of curve and really needs a dynamometer to do properly.Alec Quote Link to comment Share on other sites More sharing options...
dazzer Posted April 17, 2015 Share Posted April 17, 2015 The Distributor Doctor http://www.distributordoctor.com is good if you wanted your original dizzy sorting. Just give him the overall spec of the engine and what you are wanting to do and he'll give it an appropriate curve. CheersDazzer Quote Link to comment Share on other sites More sharing options...
Rod 2500S Posted April 18, 2015 Share Posted April 18, 2015 Thanks LadsThis might be of interest an electronic approach on a budget. http://www.siliconchip.com.au/Issue/2007/March/Programmable+Ignition+System+For+Cars%3B+Pt.1and a simpler approach which doesn't allow advance curve programming but will definitely improve overall performancehttp://archive.siliconchip.com.au/cms/A_112976/article.html Ahh I here you ask, why bother when you can buy a simple module to drop in the dizzy??, because this does heaps more, dwell control, coil protection etc.(I'm just assembling and installing this one into the old boy in the next few days)HTH CheersRod Quote Link to comment Share on other sites More sharing options...
piman Posted April 18, 2015 Share Posted April 18, 2015 Hello Rod, while swapping the points for an electronic module has certain benefits, if the distributor is worn out then it still won't be right? Also, don't forget even with electronics it still needs the occasional drop of oil to keep it functioning.Alec Quote Link to comment Share on other sites More sharing options...
Rod 2500S Posted April 19, 2015 Share Posted April 19, 2015 Hi Alecyes the dizzy must be in good mechanical condition. I can tell you from past experience with these modules that you can reasonably expect a 3-5% increase in fuel economy and some extra power, and given that these kits cost the equivalent of 30 quid here in OZ it's brilliant value.CheersRodPS oil? where does that go?? Quote Link to comment Share on other sites More sharing options...
piman Posted April 19, 2015 Share Posted April 19, 2015 Hello Rod, on Lucas distributors with an after market electronic switching unit as opposed to a full solid state distributor, remove the rotor arm and add couple of drops onto the securing screw. Ideally lift the base plate and lubricate the weight pivot points also.Incidentally I tried Google to see if I could find some information on burn rate between 60's petrol and today's but couldn't find any scientific data. I did fine web sites that stated that modern fuel burns much less slowly and that it burns faster! I gave up after a few pages.Alec Quote Link to comment Share on other sites More sharing options...
Davemate Posted April 19, 2015 Author Share Posted April 19, 2015 Well just to confuse things I've been advised to disconnect the vacuum advance if I don't want my engine to pink Quote Link to comment Share on other sites More sharing options...
thebrookster Posted April 19, 2015 Share Posted April 19, 2015 Dave - trial and error!!Run it with vacuum, then if it starts to pink pull over and remove the pipe (block the carb end though).It has also been mentioned to me on a few occasions that keeping the vacuum advance is not always conducive, mainly cause on older cars they have stopped working!Cheers,Phil Quote Link to comment Share on other sites More sharing options...
Davemate Posted April 19, 2015 Author Share Posted April 19, 2015 Both my heralds and the saloon has always had it connected and none of the above pink. Quote Link to comment Share on other sites More sharing options...
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