I was working on my 72 deville 472 and decided to hook up this old dwell meter my uncle gave me. It's a craftsman thing with all these different tests on it. I set it to dwell and with the engine running at as low an idle as it ever goes (not sure of the actual rpm) it read 24 degrees. So, I put an allen wrench in the adjuster window and turned the screw counter clockwise until I got as close to 30 as possible - every time I removed the allen wrench it seemed to move to 31 degrees, so that's where I left it for now.
The engine seemed to get a little bit smoother after the adjustment, but maybe that was all in my head. Assuming this old meter is working properly and giving an accurate reading, was adjusting from 24 a big deal? I don't know if 24 is way off or if that was just a slight adjustment - I know very little about how dwell being off actually effects engine performance (fuel economy, power, etc).
Can anyone comment on this?
also, i hooked up the inductive tach (one clip, tried it on a couple different wires) and switched the meter to Tach, and the tester wouldnt show any reading. i tried playing with all the settings but nothing worked.. i guess that part of the tester could be broken
this tester has individual plugs that you insert into the tester, one for amps, one for volts, one for rpm, etc, and the rpm pickup is just a clip that looks kind of like a small stapler - there are no 12v + or - on this setting, and the unit does have a 9v battery in the back which is used for something. what do you mean bu flipping the inductive pickup?
the battery was a little low when i tested the meter to begin with - still enough juice to measure dwell and voltage, though. for some reason the rpm inductive pickup mode nor the resistance mode would work. ill try with a new battery tomorrow.
well it turns out that adjusting my dwell was important, or did something else important, because now my 72 idles a lot better than it did before, and at a lot lower rpm. when i hit the gas it no longer cuts out, it returns right back to idle, and it sounds very quiet. the only problem now is that there's a white mist of smoke billowing up from the exhaust pipe that goes from the driver's side over to the passenger side straight pipe. im not sure why this exhaust is grey, because the exhaust coming out the back is colorless. maybe this is a good excuse to run two straight pipes and some cheap mufflers for $150 or so?
The dwell is surprisingly important. If it is too far off when you hit the gas, if there is any play in the distributer at all, and the dwell is too far gone, the spark from the points has a chance of actually missing the spark plug wire, and never delivering it to the cylinder (that's probably why it no longer cuts out when you hit the gas). Making sure the dwell is right on ensures that you will get an even spark to each cylinder consistantly. I'd say give it a little while because if it was off for too long you might have leftover gas in the cylinder, see if it goes away when the engine warms up. Also you might try an oil change to some higher grade oil because when the dwell is off and the engine is rough it can cause seal damage, which some good oil might fix. However I have a custom dual exhaust with flowmaster mufflers and it sounds great