[john walker's workshop]

adding air to the exhaust just as it exits past the exhaust valve actually makes the exhaust hotter, the object of which is to help burn any unburned fuel that otherwise would be discharged into the atmosphere. cars with air pumps run just the same as those with it removed. they do get in the way of valve adjusts and sparkplugs, and the engine does look better with it gone. emission standards for the engines that had the pumps are fairly loose, so most can be adjusted to pass smog without it, unless there's a visual test required.