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Post by Scoutpilot on Aug 1, 2015 11:18:55 GMT -5
Please review the "Tools" board. Everything there is useful in basic troubleshooting. I wanted to get a start on this section. Hints, what to look for, and both easy and hard fixes will come a bit later. As well, I invite everyone here to contribute whatever tips or tricks they may have learned over the years so that others may learn.
Oh, and there is one other obvious point I must make.
For those of you who were raised on computer-controlled electronic fuel injection. You were told "Do not pump the accelerator pedal when starting the motor." This is all well and good for a motor without a carburetor. One that has fuel, under pressure from an electric fuel pump, at the ready to go through the injectors, in the precise computer controlled quantity based on temperature and several other measurable factors and into the computer controlled air flow, based again on temperature and several other measurable factors.
BUT!
With these old carbureted, normally aspirated, points and condenser controlled spark, with a fuel supply totally dependent on a small mechanical pump, you WILL have to pump the gas pedal a couple of times and maybe even three. You will probably need a little choke, maybe as much as half, even on a warm day, applied at that very first start of the day. YOU are the computer for this old "Go Devil".
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Post by Scoutpilot on Aug 29, 2015 5:39:26 GMT -5
Let's get started with a practical reality we are all faced with. The Air/Fuel mixture.
A lean fuel mixture can cause an engine to have a surge or miss at idle and part throttle stumble on acceleration, leading to engine overheating and lack of power. A rich fuel mixture can cause an engine to “load up” at idle, foul the spark plugs, and also lack power or run sluggish.
If the A/F mixture that is delivered to the engine is excessively rich for too long the engine could leave leftover fuel from the combustion process, washing the oil off the cylinder walls. Without the oil to act as an anti-wear agent, the pistons and rings will make metal-to-metal contact with the cylinder walls. Also, if enough fuel gets past the rings and into the crankcase the oil can become diluted and lose much of it’s lubricating properties and accelerate engine wear.
Theoretically, the ideal stoichiometric A/F mixture (the chemically ideal mixture of air and fuel that is required to provide a complete burn) for a properly tuned engine running on pure gasoline is 14.7:1; that is, 14.7 lbs of air to 1 lb of fuel. However, because of operating losses in the induction system due to intake runner and cylinder wall wetting, plus the fact that fuel may not fully vaporize in the combustion chamber, a 14.7:1 A/F mixture is often too lean for actual operating needs. A more realistic light-load, cruise A/F mixture for a stock carbureted engine running on reformulated unleaded gasoline is in the 14.1:1 range.
The A/F mixture always varies from cylinder to cylinder, therefore we tend to tune the average A/F mixture slightly on the rich side to avoid engine misfire in the leanest cylinder. It is possible to target an A/F mixture leaner than 14.7:1 for maximum fuel economy but this can lead to driveabilty problems if any one cylinder is leaner than the others. The power mixture we target for maximum horsepower is in the 12.2:1 – 13.5:1 A/F range, depending on the engine package and its combustion chamber design.
The modern reformulated conventional and oxygenated gasoline of today will cause the A/F mixture to shift leaner when compared to the leaded gasoline of the 1960s and 1970s. This means if the A/F mixture was lean with leaded gasoline it will be even leaner with today’s gasoline blends.
Back in the days of leaded gasoline an experienced tuner would adjust the A/F mixture the engine was getting from its carburetor by reading the color the fuel left on the insulator of the spark plug in the exhaust port and in the first 6 inches of the exhaust header. The reformulated unleaded gasoline we have today has made reading spark plugs almost impossible because it leaves little or no color on the spark plug insulator.
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Post by Scoutpilot on Sept 5, 2015 4:53:09 GMT -5
Here's an "Oldie but Goodie" I post over at the CJ2A Page a few years ago. It never hurts to review a few things.
OK. Let's do this again. The L-134 can only run properly and efficiently when ALL systems are complete, solid and functioning correctly. The properly functioning generator or alternator produce power that runs your ignition and charges the battery (which powers your lights and other accessories) then, through the ignition system energizes the coil. The properly functioning coil discharges it's high voltage to the clean and properly insulated and functioning distributor. In the properly adjusted (timing) distributor is the properly functioning condenser, which stores that energy until the circuit is broken by the properly gapped, clean opening points. The charge is transferred to the properly maintained rotor and then through the electrodes in the clean, un-cracked distributor cap. The electrodes have clean, un-corroded sockets into which fit clean, un-corroded, properly insulated male spark plug wire electrodes. Originally all spark plug wires were copper cored. They were and still are subject to corrosion and eventual failure. Now we have graphite/silicone cores. Longer lasting, but not as conductive. And yet, still subject to break down due to heat and chemicals and age. At the other end of the wire is another electrode. A female end that should be clean and un-corroded. It fits onto the tip of another electrode. The humble spark plug. porcelain and metal, if you're lucky, or smart you have copper core, non-resistor plugs that are clean with un-cracked insulators and have positive and negative poles that are solid, clean and properly gapped. A spark.
This where the electrical system meets the fuel system. The fuel comes from a clean steel or polyethylene tank with a properly situated 'J' tube to pick up the clean dry fuel. It then flows through steel, but too often rubber, tubes to a fuel filter (hopefully) which picks up dust, dirt, lint, insects and other detritus which found its way into the gas station's tank and then to yours. Especially if you were fueling at that station while it was having a delivery (Fresh flow into the tank disturbs the detritus on the bottom and, well, think of swimming in a silt-bottomed pond.) The fuel pump which, whether mechanical (my favorite) or electrical, needs to be properly maintained. An inline filter should be installed to protect it and its delicate valves and diaphragm. The pump pushes the fuel up to the carburetor, which, without any filtration, takes all that crap into the fuel bowl. UGH! One of the jets has an orifice that is only slightly larger than a period.↵ The extremely small passages within the carburetor are subject to all manner of mayhem and blockage if the fuel is not clean and dry. Deposits form and block these passages, jets and valves. A speck of grit no bigger than a period will stop you dead in your tread marks. Once through the clean and properly adjusted and functioning carburetor, the fuel is mixed with air in the venturi of the carburetor.
Bear with me, we are almost to your answer.
The fuel is sucked into the intake manifold which is mounted with the exhaust manifold for a reason. That reason is heat. Exhaust heat to be precise. The two passages (in an out) are separated by the cast iron base of the intake manifold. The heat riser, when properly installed and maintained is open at the cold start allowing warm exhaust to flow up and directly at the intake manifold. As the warm air passes by the intake manifold it warms the manifold and thereby warms the fuel/air mixture so it can properly atomize in the cool intake, pass through the properly adjusted intake valve supported and restrained by the solid spring, the shaft passing through the properly lubricated and sized valve guide and bathed by clean dry oil from the crankcase, and then into the properly lubricated, clean, unscratched or gouged cylinders, where it is compressed by the properly maintained piston and its rings at the proper point the properly function aforementioned systems will unite to create an explosion. Found also in that compressed mix are volatile gases and moisture which have accumulated in the crankcase and because of the heat riser properly functioning are here because that heat causes pressure in the crankcase. The suction of the intake, possible in no small way due to the properly functioning heat riser, allows the PCV valve to open and suck those gases and moisture out of the crankcase. If left there they would cause sludge and rust. Both enemies of your motor's crank, cam, bearings, piston rods, etc. Now then, it is time to expel the burned gases. The properly maintained and adjusted exhaust valve, supported and restrained by it's properly lubricated spring, slides through the properly lubricated valve guide because the heat riser is working.
But I'm not finished.
The hot exhaust gas exits through the exhaust manifold and now encounters a heat riser valve that is closing and is more fully directed out the exhaust pipe because the motor has warmed sufficiently to warm the fuel/air mixture all by itself. So the excess hot gases are no longer needed. While this is happening, the PCV valve is relaxing on it's spring because it is now only needed at acceleration.
I'm still not finished.
The exhaust usually passes through the manifold past a properly tightened and gasketed connection to a pipe and then through a (hopefully) unrestricted and solid muffler. The back pressure is absolutely required.
My point here is that ALL systems must be properly maintained and adjusted in order for the ENTIRE motor to work correctly and efficiently in conjunction with the clutch/transmission/ transfer case group. If one is out of spec, it eventually brings every system down.
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Post by Scoutpilot on Feb 19, 2016 13:12:58 GMT -5
The Vacuum Gauge is an invaluable tool when it comes to diagnosing problems. The level of vacuum and the movement of the needle on the gauge will tell you pretty much what you need to know about the health of the motor. I use a Vacuum Gauge in my day to day testing of the carburetors I rebuild. Not only does the gauge tell me if the carb is leaking air it also gives me a daily check on the condition of the motor. For more information on how to interpret the vacuum gauge just check out the chart below.
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