Triumph Repair: Spitfire valve rattle, vacuum advance, deep pockets

Question
Hey Howard,
  This is a follow up of my question (Spitfire 1500 Valve Rattle). The engine came out of a Spit built for racing. It orginally had a Mallory Elec Dist and I changed it to a 45D4 with elec ignition. After much reading and thinking I decided to reset the timing back to 10 BTDC but this time I disconnected the vacuum advance. The care runs much stronger through all rpms and the rattle noise is gone. The Mallory dist it came with did not have vacuum advance. The question is this, can I leave it that way or do I just need to swap it back to the Mallory?

Answer
Hi Mark,
Any time you modify any engine, you change the ignition advance and timing. The advance curve is different as well as total timing. The ideal timing and advance curve is always just short of detonation. Many new street cars have knock censors that give feed back to an ECU to back the timing up just a little and some even have that on each individual cylinder. You can buy those systems in the aftermarket to fit any engine from MSD and Electromotive but they are expensive. (Well over $1000.) If you don't have deep pockets you can get a LED display of a knock censor so you can see high RPM detonation (ping, knock, rattle or what ever you want to call it)(MSD and it is only a few hundred bucks)(well worth it) With that you can get total advance and work your way down the RPM/load range and adjust the advance curve to get the most out of the engine without the worry of detonation that can destroy an engine. Some detonation can not be heard like what you heard but is destroying the engine. It is a complex process to get the best advance curve and total timing after modifying an engine. Armed with the right tools and a little knowledge of what you are doing will get you in the ball park.
Howard