riverstar Posted March 31, 2015 Report Share Posted March 31, 2015 I read that Accuspark are offering a programmable ignition box for under £100. I have been using a Accuspark system for three years and am very happy with the result however as most owners I want my engine to run as efficiently as possible and at the same time offering the best performance. As my knowledge of the more technical aspects of ignition is limited I would be grateful others views also what should I expect if fitted. I run a standard 4A engine re built two years ago following a split liner also professionally re built carbs four years ago. Chris Quote Link to post Share on other sites
TriumphV8 Posted March 31, 2015 Report Share Posted March 31, 2015 From the theory a ignition timing as precises as +/-3 degrees compared to the theoretically perfect timing at any engine working point is required to get the best results. The required timing relies on filling of cylinders and rpm of the engine if the engine is seen as a black box to make it not too complicated. (Any change of compression, mixture by the carbs or cam as the main influence would change the timing requirements) That will require a full 3D ignition table with rpm and MAP/TPS at the axes like MegaSquirt and Megajolt can provide. The question is how deep somebody is willing to step into that topic and how precise he will be able to get the required data. The accepted minimum for ignition advance is the rpm advance, nearly every 4-stroke engine will provide that. Next step is the vaccuum advance that most engines provide but at this stage the first different opinions occure. It is showing the above mentioned filling of the cylinders. Especially when carbs like Weber DCOE are added, the vaccuum is often disconnected. Unknown by many is that even a connected vaccuum advance on a conventional distributor will fail to work perfectly when the cam is changed seriously. So many tuned engines run without or with a limited vaccuum advance system what more or less costs some fuel and crispy response to the throttle. If a vaccuum advance is preferred and a Megajolt is too complicated I would fit a 123 where the "tune" version is the better one. Besides the timing a modern ignition should also control the dwell time because if changed to electronis I would do that perfect. Most of the "Cheap Charlys" only swap from points to electronic without dwell control. The added boxes for timing control often do not provide vaccuum advance. Both should be checked before buying something that can not offer all necessary features. Anyway even the swap from point to electronics is a good step forward and its upon each individual judgement how far somebody wants to enter that topic further. For me with the MegaSquirt it was no question because I had the datafields and had to fill them all with data that make sense. Quote Link to post Share on other sites
peejay4A Posted March 31, 2015 Report Share Posted March 31, 2015 I think the Accuspark box does dwell control but I'm not sure how it deals with vacuum advance, if at all. Quote Link to post Share on other sites
Steves_TR6 Posted March 31, 2015 Report Share Posted March 31, 2015 Interesting topic. I'd like to move to programmed ignition on my 6, as much for the fun of it as for the potential improvements. Presently am favouring a 123Tune or a full distributorless system, but this AccuSparc does sound interesting. Steve Quote Link to post Share on other sites
seanlen Posted March 31, 2015 Report Share Posted March 31, 2015 Chris There are some demo videos on youtube for product you are talking about just type in accuspark and you should find the guides. Sean Quote Link to post Share on other sites
Peter Cobbold Posted March 31, 2015 Report Share Posted March 31, 2015 I think the Accuspark box does dwell control but I'm not sure how it deals with vacuum advance, if at all. Pete, I agree. Nowt here mentioning vac advance: http://www.accuspark.co.uk/Blackbox.htm Nor boost retard !! The Programmable 123 does both those. Peter Quote Link to post Share on other sites
Lebro Posted March 31, 2015 Report Share Posted March 31, 2015 Having just looked at the web page above, I would venture to suggest that the vacuum advance already present in the distributer can be retained. To disable the centrifugal advance you just need to lock up the bob wieght system, but this will not affect the vacuum advance which rotates the whole baseplate. Still not convinced I need one though ! Bob. Quote Link to post Share on other sites
TriumphV8 Posted April 1, 2015 Report Share Posted April 1, 2015 Good idea and without the opportunity of these electronics availiable a suitable way to go! But why todays combine technique from the Stoneage with modern electronics and suffer from both disadvantages? I was always wondering about the success of the 123 where electronics is supposed to bad climate in the engine compartment. Than I learned that 123 needs only 3 cables to be connected and thats it. Probablay one of the main reasons for its success. On each step away from a full programmable solution like Megajolt you sacrifice something like possibilities of setup or reliability. What you get back buying a cheap Charly is a few bucks saved and little bit of brain saved to get in touch with the details of a more complicated system. From my experience the money will be long forgotten when the owner runs into limits of setup that will meet him every day again..... Quote Link to post Share on other sites
riverstar Posted April 1, 2015 Author Report Share Posted April 1, 2015 If I was starting from scratch I would go with the 123 Tune however I have a Accuspark fitted which is working just fine and I find it hard to justify scrapping especially as I have some other jobs I plan to do on my return to the UK Quote Link to post Share on other sites
Nick Jones Posted April 3, 2015 Report Share Posted April 3, 2015 Accuspark system is 2D only with no load sensing. This is fine for competition applications where full throttle is the dominant driving mode but is really a downgrade from any system that includes vacuum advance. While I take the point that it may be possible to retain the mechanical vacuum advance, for me this is a very poor substitute for having full 3D control. One of the greatest benefits I found when I went to programmable ignition was to be able to tinker with the advance at part throttle for best torque in normal driving and best cruising economy. This would also be true even on systems where vacuum advance is not used (eg some PI variants) as I think the reason for not using vac advance on them was the crude vacuum systems not being able to make very good use of the fairly limited vacuum signal. For my money, the best systems are distributorless. The Megajolt/squirt based on Ford EDIS hardware being the DIY entry-level one (and none the worse for that functionally). These are more work to install but can be pretty cheap if you are DIY able. Next comes 123-Tune which offers nearly all the advantages of the dizzy-less but is much easier to install. There are other add-on boxes which do offer 3D control (Aldon do one) but these are more costly putting them near the 123-Tune bracket. Nick Quote Link to post Share on other sites
John L Posted April 3, 2015 Report Share Posted April 3, 2015 The Aldon one will do both vacuum and boost, but in separate boxes. http://www.aldonamethyst.co.uk/ John Quote Link to post Share on other sites
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