In fact, Terry, they originally were before the tubeless and steel belted radial tires, back when an air pump and a tube patching kit routinely rode with the jack and lug wrench, and a road trip of any length could count on a few stops to change a flat. Charles > Them things were about before the advent of the cheap plug-in compressors > Jeff - they were popular as an alternative to hand pumping back in the > 70's - also pre electronic ignition, oxygen sensor and catalytic > converter. > > > >> This is NOT a good idea for the reason you mention and several others. >> Depending on the type of car, and how you do it, you may also damage the >> electronic ignition, oxygen sensor and catalytic converter. >> >> If you need a cheap and dirty small air compressor, go to a DIY auto >> store >> and get a $10 USD one that plugs into the cigarette lighter on the car. >> It >> is meant to pump air to 75-80 psi or more and probably costs less in time >> and money than buying or making a check valve and possibly damaging the > car >> using it. >> >> Good luck, Jeff Dayman Waterloo Ontario Canada >> >> > Actually, Tony, you COULD replace one of the spark plugs in your >> > automobile >> > with a check valve and use that cylinder as a compressor. MODEL ENGINEERING DISCUSSION LIST. To UNSUBSCRIBE from this list, send a blank email to, modeleng-request@xxxxxxxxxxxxx with the word "unsubscribe" in the subject line.