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I did some research awhile back concerning Engine Tuneup and noticed that the more modern engines use something that most of us are very unfamiliar with. The item I am referring to is the Oxygen (or O2) Sensor. The idea of knowing EXACTLY where the sweet spot is as far as fuel mixture was very intriguing to me. I went about learning about this technology and then proceeded to install one in my 235 Test Engines Exhaust System.
The O2 Sensor makes its own voltage based on the amount (or lack thereof) of fuel to oxygen ratio. A 14.7:1 ratio, or 14.7 parts oxygen to 1 part fuel is THE sweet spot and you will find this correlates to the best possible gas mileage, the best possible engine tuning, and will help keep Valves cleaner and give the very best engine performance possible. This is because dumping too much fuel into your engine just causes it to drip out of the exhaust as unburned fuel, or worse yet, soot that coats all of your engine internals. More fuel than the air mixture can deal with does not provide a performance boost. More air than fuel is also not desirable.
Us old Chevy Truck owners with 216/235/261 engines are at a disadvantage because we just turn the carbs mixture screw out a turn and a half (recommended) to start, then adjust more or less by how the engine is running. I thought it would be cool to try this technology out, so I purchased a one wire, first generation O2 Sensor. It is a Standard SG5. You also need to drill a 7/8" hole in your engines exhaust pipe about an inch or so down from the flange. As close to the manifold connection as possible. Then, you need to install a Bung. It is just a 3/4" threaded Nutsert that is welded into the pipe, then the SG5 is screwed into it. The SG5 has a probe that sticks down into the exhaust stream.
Where the Tip comes in this week is, you do not need a special gauge for this setup. All you need is a Multimeter set to DC Volts that can read between 1 volt and 100 millivolts. The one wire coming out of the SG5 is the Red (Positive) lead and engine ground is your Negative Lead. 1 Volt means way too rich, while 100 millivolts means way to lean. 500 Millivolts is your 14.7:1 sweet spot. Fire up the engine, and let it get good and warm, then watch the meter at idle. Adjust your fuel mixture screw on the Carb for the sweet spot and now you have a way of fine tuning your engine that you didn't have before.
Want to watch a movie starring a 1959 235 Engine that goes through this? Here you go...
https://www.youtube.com/watch?v=zz7Osir2mQQ
Between being able to fine tune my fuel mixture at different RPMs and the HEI Ignition, this test engine is always getting comments from the locals on how smooth and how quiet it is. Have a great week!
The O2 Sensor makes its own voltage based on the amount (or lack thereof) of fuel to oxygen ratio. A 14.7:1 ratio, or 14.7 parts oxygen to 1 part fuel is THE sweet spot and you will find this correlates to the best possible gas mileage, the best possible engine tuning, and will help keep Valves cleaner and give the very best engine performance possible. This is because dumping too much fuel into your engine just causes it to drip out of the exhaust as unburned fuel, or worse yet, soot that coats all of your engine internals. More fuel than the air mixture can deal with does not provide a performance boost. More air than fuel is also not desirable.
Us old Chevy Truck owners with 216/235/261 engines are at a disadvantage because we just turn the carbs mixture screw out a turn and a half (recommended) to start, then adjust more or less by how the engine is running. I thought it would be cool to try this technology out, so I purchased a one wire, first generation O2 Sensor. It is a Standard SG5. You also need to drill a 7/8" hole in your engines exhaust pipe about an inch or so down from the flange. As close to the manifold connection as possible. Then, you need to install a Bung. It is just a 3/4" threaded Nutsert that is welded into the pipe, then the SG5 is screwed into it. The SG5 has a probe that sticks down into the exhaust stream.
Where the Tip comes in this week is, you do not need a special gauge for this setup. All you need is a Multimeter set to DC Volts that can read between 1 volt and 100 millivolts. The one wire coming out of the SG5 is the Red (Positive) lead and engine ground is your Negative Lead. 1 Volt means way too rich, while 100 millivolts means way to lean. 500 Millivolts is your 14.7:1 sweet spot. Fire up the engine, and let it get good and warm, then watch the meter at idle. Adjust your fuel mixture screw on the Carb for the sweet spot and now you have a way of fine tuning your engine that you didn't have before.
Want to watch a movie starring a 1959 235 Engine that goes through this? Here you go...
https://www.youtube.com/watch?v=zz7Osir2mQQ
Between being able to fine tune my fuel mixture at different RPMs and the HEI Ignition, this test engine is always getting comments from the locals on how smooth and how quiet it is. Have a great week!
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