If you're changing the oil pressure sending unit for the dash gauge or light, you don't have to drain the oil. A little will dribble out. You just don't want the engine running while you do that or you'll have a dandy surprise.
You're the third Ford owner today to ask about more power. What do you mean by "more lean"? The Engine Computer monitors the fuel mixture in the exhaust and it fine tunes that mixture for the lowest emissions. There are some things you can do to trick the computer into commanding more fuel, but you'll be lacking the additional air needed to get any power from that gas. You're limited by the volume of the cylinders.
One thing we used to do on racing engines was to change the camshaft timing. Two degrees makes a huge difference in the personality of an engine. Your camshaft sprocket is positioned by a dowel pin in the camshaft. You used to be able to buy a new sprocket with multiple dowel holes. You selected the hole that provided the amount of change you wanted. They were really meant for "blueprinting" an engine which just means building it exactly to very tight original specifications, but they were available to build the engine for specific purposes too. You also used to be able to buy offset dowel pins to accomplish the same thing.
If you remember "T" for "tight, "T" for "top end", and "T" for, ... Uhm, ... "Advanced", if you would tighten the pulling side of the timing chain that would advance the camshaft making the valves open sooner. That would increase torque at the high end of the rpm range.
If you remember "L" for "loose", "L" for "low end", and "L" for "late", a loose timing chain will make the valves open late and that will increase low-end torque while sacrificing high-end torque. This is typically done in motor home engines that need the torque on the low end to get going at stop signs. You won't pass anyone at highway speeds with those engines without a mile head start.
I have a 440 c.I. Out of a highway police car. Everyone knows those are major powerhouses, but mine goes from 0 to 60 mph like any old 318 c.I. From 60 to 90 it comes alive and just about tears the seats off the hinges! It was made for highway pursuit and the cam timing was tailored for that.
I also have a 318 c.I. That I totally rebuilt, and used a gas mileage camshaft. Come to find out it was the exact same part used in motor home engines. I could squeal the tires all over the place with the additional low-end torque, and it did increase the fuel mileage on that big old station wagon.
A lot of people notice their tired old engines seem to have lots of power when taking off but they have a hard time passing other cars on the highway. That is due to a worn timing chain that makes the valve timing late. Simply replacing the worn chain and sprockets will restore the high-end power.
Thanks to the politicians and tree-huggers, there isn't much else you can do. The exhaust system is already plenty free-flowing even with the catalytic converters. Anything else you can modify to get more power is going to increase emissions, and that's where the rub comes in. We used to install camshafts with different valve overlap and duration but those just moved the power band around to the desired range for a specific purpose. You have to increase the compression ratio or the volume of the cylinders to get more power. Short of adding a turbocharger to stuff in more air, there's no practical way to get more power.
Wednesday, February 12th, 2014 AT 7:11 PM