Hi, what is a good spark plug gap for my car. I have a 1972 455 stage 1 motor whit a hei. I have ngk ur-5 plug and all my plug look very white whit this plug. thanks mat
.045 is a really good gap to run with an HEI. It may take many miles for plugs to color. I wouldn't worry about it. I run the UR-5, at .045. I really like that plug.
But whit my plug are very white. my carb is to lean ? do I have to have less advance whit those plug ?
It may not be too lean. With good spark and combustion, it may take awhile to see color on the plugs. You may find the motor needs less advance with a projected nose plug. The best way to find out how much advance your motor likes is to run it at the track, or on a chassis dyno. The timing that gives the most horsepower, or the most trap speed will be your optimal total timing.
how can I know when the car is too lean because my car ping even if I put less timing, it ping only at full throtle.
The best way is with an exhaust gas analyzer. You can get an idea though with this trick. Warm the car up to full operating temperature. Then raise the engine speed in neutral to around 2000 RPM. Block open the throttle, or have someone help you. Then slowly close the choke a small amount. If the engine slows down, the mixture is good, if it speeds up, you are lean. You want the engine speed high enough so that the carburetor is running on main metering. This will give you a rough idea if you're lean or not. Sometimes you may need to mix in a little leaded race gas to stop detonation. I know my motor needs 2-3 gallons of 110 leaded race gas to a tank full of 93 pump gas.
