Any of the calibration software (like LT1 Edit or HP Tuner) gives you more knobs than you know what to do with. Tuning in the WOT ranges is a good place to start. However, without a chassis dyno equipped with a wideband O2 sensor, your tuning will be hit and miss at best. Also, you said you have the "rest of the goodies" on your car. That would lead us to believe that you have a set of headers, high flow cats, and a performance after-cat exhaust system. If you don't have these components in your build, you need to start there. Adding all those performance upgrades up front and nowhere for the exhaust to go is a power-killer. Get your car on a chassis dyno and tune the WOT fuel for the 12.5 to 1 air/fuel ratio. This is a safe place to start. Next, step up the ignition timing 2 degrees at a time. Watch the knock sensors through your software and tune it to peak horsepower, or back off the spark about 2 degrees when you find knock on the knock sensors. This should give you a good starting point. Also, look for spark retard because of inlet air temperature. There will be a spark table that relates inlet air to degrees of spark retard. As the inlet air temperature increases, the computer pulls spark out of the calibration to prevent knock. Most of the factory calibrations were overly conservative in this area. As the car heats up, and the cooling system blows hot air across your cold air intake, it kills the spark advance. Check that out first.
You could probably sell tickets to the light show under your hood at night. I'm surprised after that many sets of wires and plugs you haven't come across a combination that has taken care of your flashover. You said you have tried many plug gaps. Well, the wider the gap, the more spark energy is required to jump the gap. The spark is looking for the easiest path, and in your dry climate it must be to the plug shell. Gap your plugs at 0.035 inches and apply MSD Spark Guard to the spark plug boot. This is dielectric grease that helps prevent flashover. You can pick up a tube of Spark Guard under PN 8804. For more information contact MSD at (915) 857-5200, or online at www.msdignition.com.
Fuelish PleasuresQI have a 454 Chevy with oval-port open-chamber heads, a Team G manifold, Holley 750 double pumper, a Lunati cam (0.540/0.558 inch max lift, and 237/247 duration at 0.050 lift), and a MSD 6AL box with a Blaster coil. My spark plugs are almost black after running the engine for about 10 minutes. I've tried changing the plugs, which made the car sound different and seem to rev quicker for about 10 minutes, at least until the rich smell of exhaust came back with black plugs. Also, I'm using a new carb out of the box with Autolite #25 plugs. I am 60 years old and have not been on the track for about 35 years, but I have the bug again. By the way, I didn't build this car. I bought it from someone two months ago. Thanks in advance for any help you can give.Lee RobinsonVia e-mail
A.Your combination shouldn't be loading up the plugs that quickly with the factory calibration. First you need to check out all the adjustments on the carb. Have the float levels been set since the carb came out of the box? Remove the sight plugs from the float bowls one at a time and adjust the floats until the fuel level is right at the bottom of the sight hole with the engine idling on level ground. If you find that the floats are adjusted properly, we'll bet you have a blown power valve. This is usually caused by a backfire through the carb. Now, it may have never done this to you, but if the carb was too lean for the previous owner and it backfired, the power valve could be at fault. You should only have a power valve on the primary side of the carb.