The Ford Barn - View Single Post - !952 Mercury with 255 Flathead V-8 Will Idle But Not Gain RPM.

vincent · 02-27-2025, 04:22 AM

Opening the throttle raises the compression. Therefor the spark needs more energy to ionise the air between the plug gap in order to jump and ignite the mixture. Wet plugs give a less resistant path for the energy down the porcellan so they tend to spark when out of the engine but will not when working against compression.

02-27-2025, 04:22 AM	#2
vincent Senior Member Join Date: Jun 2020 Location: Germany Posts: 242	Re: !952 Mercury with 255 Flathead V-8 Will Idle But Not Gain RPM. Opening the throttle raises the compression. Therefor the spark needs more energy to ionise the air between the plug gap in order to jump and ignite the mixture. Wet plugs give a less resistant path for the energy down the porcellan so they tend to spark when out of the engine but will not when working against compression.