Peter Henry Andersen Posted September 24, 2020 Share Posted September 24, 2020 Hi, I have old CDI unit and my RPM needle is bouncy at idle and more bouncy at speed/movement... I suspect the CDI unit as it's old, but my attention is also to the coil. When I bought the car it had a black BOSCH coil worked fine, but wanted to replace it with anew on. So bought a Sliver BOSCH from rosepassion. This was 1,5years ago. After a drive 300km the RPM needle started to act funny / bouncy. Got home. Next it was fine again, but start to bouncy some days later and now it's not stopping. Car feels tired.... So my question. Which coil is the best with this CDI+ unit. I want the best for my 911. I found this one from Perma tune: https://www.hovwdiaudi.dk/product/?id=1691600500&cbrand=porsche&cmodel=911/930 And there is a black BOSCH and a SILVER - Which is the best and give the best spark. Thanks in advance. Best regards Peter Henry Andersen 1 Quote Link to comment Share on other sites More sharing options...
classicretrofit Posted September 25, 2020 Share Posted September 25, 2020 Hi Peter Bouncing tach needle is often a sign of a failing voltage regulator so check that out. We've tried all sorts of coils with our CDI+ and the original is currently the best. So you might find that old black coil and refit it. Silver coils are not good. I could tell you a few stories about aftermarket vendors but let's just say the only way forward for us was to make our own unit, which we have done. The good news is that we have several brand new Classic Retrofit prototype coils in test with engine builders in the UK and US and we are also running a prototype coil on our own car. Handbuilt to a very detailed specification, it comfortably outperforms everything else. We expect a product launch in Q2 2021, subject to more testing hours clocked up in the interim. Next week's video will give a look at the coil - watch out for that! Quote Link to comment Share on other sites More sharing options...
HX911 Posted October 28, 2020 Share Posted October 28, 2020 I had a very similar experience, car ran fine, then suddenly lack of power and tacho needle all over the place. Searched for electrical faults, swapped CDI, no help. Then my mechanic had a feel of the distributor button - the bearing was worn, causing the cam to wobble, causing irregular sparks. New old dizzy fixed this! Still upgrading to the CDI+ though, so many advantages, and how long will my original CDI last.....? 1 Quote Link to comment Share on other sites More sharing options...
classicretrofit Posted October 28, 2020 Share Posted October 28, 2020 1 hour ago, HX911 said: Still upgrading to the CDI+ though, so many advantages, and how long will my original CDI last.....? Many advantages and we are always chipping away, adding more features and refining the design. It is a great product 😉 Quote Link to comment Share on other sites More sharing options...
HX911 Posted October 29, 2020 Share Posted October 29, 2020 Of course it is!😇 - xmas cant come soon enough, so I can fit it! Any suggestions how to disable the centrifugal advance on a 74 911, the old style distributor? As I understand it the suggested method, and locking collar only works on the later ones.... Quote Link to comment Share on other sites More sharing options...
Jonny Retrofit Posted November 1, 2020 Share Posted November 1, 2020 On 10/29/2020 at 11:29 PM, HX911 said: Of course it is!😇 - xmas cant come soon enough, so I can fit it! Any suggestions how to disable the centrifugal advance on a 74 911, the old style distributor? As I understand it the suggested method, and locking collar only works on the later ones.... Correct, the locking collar is only for the SC and Turbo distributors. Locking an earlier distributor is fairly easy. If you remove the vacuum unit, points, side clips and the 'spade' connector, you can pull out the internals to reveal the weights. I am not sure if all units are the same but on the early ones, there is a rectangular steel plate with the weights beneath. Put the unit in a vice, to stop the gear rotating and turn the centre shaft and watch the weight move. You want to lock the weights so they are fully out. best way is to drill and tap an M4 hole in the steel plate and insert an M4 screw as shown (top right of steel plate). 1 Quote Link to comment Share on other sites More sharing options...
HX911 Posted November 1, 2020 Share Posted November 1, 2020 great, thanks. Quote Link to comment Share on other sites More sharing options...
Steve Posted January 17, 2022 Share Posted January 17, 2022 Do you drill through the weight so the M4 screw will go through the weight? And I would think you remove the spring? Quote Link to comment Share on other sites More sharing options...
Jonny Retrofit Posted January 20, 2022 Share Posted January 20, 2022 No, not drilled through, the screw is positioned to stop the weight from moving. Quote Link to comment Share on other sites More sharing options...
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