All the manuals I have in my library, some of the names are confusing like Singer Roadster…but which Roadster ? you will have to open them and decide on your own if its the one for your car. You can see the front cover to help decide. Also, as far as I know there was not dedicated Singer 4AD workshop manual, there is a Hunter manual and a Roadster supplement which is the correct engine. From that, you can figure out the entire manual. Also, I have a absolutely flawless 4AD owner’s manual that NASOC reproduced a good 15-20 years ago, I know I have it, still in the plastic bag., I just can’t find it, but I will scan it when I find it and add it here.
Click on picture to download PDF
 A Mini 4AD Manual |  Hunter Technical Service Manual |  Singer SM 1500 Supplement to the Hunter manual, to include 4AD engine. |
 Singer Gazelle Manual |  Singer 9, 4A and 4AB Manual |  Singer SM 1500 Catalog of Spare Parts |
 SM 1500 Technical Manual |  Singer Roadster Manual |  Singer 9 Roadster Manual |
 Singer Bantam and 9 Coupe Manual |  Singer 1.5,14hp and 2 Litre Manual |  Singer 1.5 Litre and 9 Manual |
 Singer 9hp Roadster Manual |  The Motor Trader 4AD article, very complete short manual |