learned something today Options

[TheCabinetmaker]

I have a 2056 with raby 9550 cam, and 9:1 compression ratio. I've recently had some problems with pre ignition with a fully warm engine. It usually happens when transitioning from cruise to WOT. I tried retarding the timing to no avail. The engine has been increasingly hard to tune and inconsistent. I could just not get the timing, dwell, and afr to work together at idle.

Whist searching the net for something unrelated, I stumbled on a page at the ngk website. Now, I've always used ngk BP6es plugs with never a problem. the article explained the causes and effects of pre ignition (or detonation). With the info from the article, I deduced that my 6's were too hot, and that my.034 plug gap was too great. This morning I replaced the 6's with 7's and reduced plug gap to 28. The difference upon startup was quite pronounced. The idle smoothed, I was able to obtain 12.7 afr at idle with the ecu knob, and re advance the timing to factory specs. the results were a smoother acceleration with what felt like(butt dyno) increased power in the upper rpms, and no detonation. I'm shocked at the difference a cooler plug made.

Hope this helps if your having a similar problem