Over the course of the last few months I have learned a tremendous amount about our Landy - a Series IIIS Land Rover (R6 model) with a 4.1 litre Chevrolet engine. I have decided to note down a few of things, mostly as a reminder to myself so I don't forget. Perhaps someone else might find this information useful or interesting as well.
I set the final timing in Windhoek, which lies at an altitude of about 2000 meters. The timing is therefore set to about 10 degrees. At sea level the timing should be retarded to about 6 degrees but if there is no "pinging" I probably will not bother adjusting it. The mechanical advance, advances the timing by another 12 degrees and the vacuum advance by a further 10 degrees to give a total advance of about 32 degrees. The vacuum advance is only effective at cruising speeds as under load or slower speeds the vacuum falls away.
To set the timing, simply loosen the one bolt underneath the distributor and turn slightly. Counter clockwise advances the timing and clockwise retards the timing.
The vacuum advance will give you improved fuel consumption at cruising speeds. I had to replace the vacuum advance as the diaphragm had deteriorated. Unfortunately the replacement was a used unit and soon failed as well. As I could not find another replacement, I decided to attempt fixing the broken vacuum advance. The unit is held together with a metal lip on one half that is pressed and sealed onto the other half. I carefully bent the lip open and the unit came apart. Inside there is a pin that is riveted through the rubber diaphragm and extends out of the casing with a slot or hole at the end where it connects to the distributor. I ground the pin off with a dremel and replaced the deteriorated rubber with a 0.8mm thick rubber material. Instead of a rivet, I used a short bolt and nut with lock-tite to secure the pin through the diaphragm. I then assembled the unit, ensuring that the lip was folded down tightly on the periphery of the rubber to secure the seal. To test the unit, just suck on the small pipe coming out of the vacuum advance and see that the pin coming out of the other side moves.
The lower the octane you are using, the more the timing needs to be retarded to prevent "pinging" and pre-ignition. For example, at sea level with a relatively low octane you may need to retard the timing to two degrees.
There are many factors that contribute to fuel consumption! Generally if your fuel consumption is too high, you are running rich which either means not enough air or too much fuel entering the engine. However, running too lean can cause an increase in fuel consumption as well!
You can get a good indication of how your engine is running by looking at the tailpipe. Dark gray is a healthy colour in the tailpipe. White residue in the tailpipe is generally an indication that your engine is running too lean and black residue is an indication of running too rich.
Possible causes of high fuel consumption include:
You should ensure that your timing is set properly and that the vacuum advance works. See the above section.
To improve your fuel consumption, you want your engine to run leaner - but careful here, too lean and you will risk overheating and could end up using more fuel as well! Check your air flow is correct by ensuring your air cleaner is clean and not restricting the flow. Make sure the choke cable moves freely and does not stick and remain partially closed as this too will restrict the air flow and cause higher fuel consumption.
Depending on the carburettor, there are various setting that can be adjusted which can alter the fuel consumption and performance. Also, various parts can wear which will cause higher fuel consumption. Worn jets and needles will cause the engine to run richer and thus use more fuel. In this case these should be replaced. Setting the float level is fairly simple and should be set to spec or can be fiddled with, trial and error style, until a better consumption is achieved. Setting the float level lower will cause the engine to run leaner. The height of the needle also plays a role and can be adjusted by slightly bending the metal bracket to which the needle is attached. Lowering the needle will cause the engine to run leaner.
The carbon monoxide (CO) level present in the exhaust gas can be checked with a gas analyzer and is a good indication of fuel consumption. The higher the CO level, the richer your vehicle is running. Generally, at idle the reading should be between 3-4 percent. As you pick up the revs and the carburettor switches from the idle jet to the intermediate jet and then to the power jet, the CO level should actually drop to around 2 percent for best fuel efficiency.
Other factors that could contribute to higher fuel consumption include:
Overheating can be caused by a wide variety of factors or a combination of them. It can be something simple and easy to remedy such as a loose fan belt or much worse, a blown cylinder head gasket or even worse, a crack in the cylinder head itself. Start with the simple things like checking the water level, fan belt tension and condition and then perhaps the thermostat. Take the radiator cap off and see that the water is circulating through the radiator. Often an overheating problem is radiator. Some of the symptoms of a blocked radiator can be the same as those for problems with the cylinder head. Don't make any assumptions!
Plausible causes of overheating:
Do you suspect a blown head gasket or crack in the cylinder head? The following are some of the symptoms to look for:
If you exhibit any of these symptoms or combination of them, it is likely that you have a blown gasket or a crack in the cylinder head. A quick test that you can have done at a radiator shop is to test for exhaust gas in the coolant. A plastic vile is filled with a blue chemical that turns yellow with very low levels of exhaust gas. The radiator cap is taken off and the vile is sealed on to the radiator with a rubber one-way valve. Exhaust gas present in the cooling system will turn the blue liquid yellow with the car running at low revs. Careful though! The coolant will also turn the blue liquid yellow. Therefore, if you have a restricted radiator, there will be extra pressure build-up in the system and it is quite possible that the coolant gets forced up into the vile, giving a false reading. Make sure this test is done properly!
If the common and simple things have been checked and you are uncertain whether there is a problem with the cylinder head or gasket, I would recommend having the radiator checked before you commence any engine work. Make sure the radiator shop takes the tanks off and checks that all or most of the channels in the core are not obstructed.
I had to replace the entire suspension on the Land Rover, which is generally a fairly straight forward task except for the chassis bushes! With the right tools - a hydraulic press, the removal of the old bushes and installation of the new bushes is fairly easy. Without the proper tool, it becomes a bit of a mission. I didn't have the proper tools.
To remove the chassis bushes, I used a drill to remove the rubber part of the bush between the outer casing and the inner tube. Remove enough rubber so that you can punch out the inner tube. Next take a hacksaw and cut through the outer casing of the bush but be careful not to damage the vehicle's chassis. Once the casing is cut through all the way, take a metal punch and fold in the casing next to the cut until it pops out of the chassis. To install the new bush, I used a threaded rod with thick washers and nuts. First, sand the hole in the chassis to remove any burrs that you may have caused with the hacksaw. Lubricate the hole and the bush with an agent such as copper slip. Thread the rod through the bush and through the hole in the chassis, use a large washer that completely covers the hole in the chassis and thread on a locking nut on the inside end of the rod. put a washer and nut on the outside end of the rod and slowly turn the nut, pressing the bush into the chassis. Occasionally tap the bush to ensure it is going in perfectly straight!
Alternatively you can install poly bushes, which each come in two parts and install in a matter of seconds.
The brakes on a Series III Land Rover are a bit of a pain. I have had at least six mechanics, some that have had years of experience, try to fix my brakes. After eight months and still not decent brakes, I've taken matters into my own hands.
Adjusting
Series III brakes appear to need an abnormal amount of adjusting to maintain proper operation. Each brake bad has a separate adjuster at the back of the drum. The adjuster is simply a snail cam which moves a post on the brake shoe either closer or further away from the drum. These adjusters have a tendancy to seize, fall off or strip. If the adjuster seems like it is just spinning and you don't feel any change in tension or hear anything, chances are the adjuster is stripped. Remove the brake shoes and install a new adjuster. Make sure the snails face the same way when you install them. When you install the new snail, hold the main adjuster bolt from the back with an appropriate socket and turn in the screw holding the snail into the adjuster bolt. The adjuster bolt has a serrated edge which pressed into the snail.
Once the adjusters are functioning, install the drum and wheel. Adjust the wheels one at a time. Have someone depress the brake pedal and tighten both adjusters to their max. Careful not to force the adjuster. In some cases you may be able to turn the adjuster past the max at which point you will hear a click and ease of turning. Release the brake pedal. The wheel should now be unable to turn. Undo the adjuster bolts slightly so there is just a little friction of the brake shoe touching the drum. Having someone hold down the brake pedal while you set the adjusters ensures that the brake shoes are seated properly.
Removing/Installing Brake Shoes
The front shoes are relatively straight forward to remove/install whereas the back ones are a little more difficult. Both upper and lower springs hook from the back of the shoe. Hook the two brake shoes together with the lower spring and slide assembly over the hub. Twist the assembly slightly so that you can install the upper spring. Turn the brake shoe assembly into correct orientation and press the top of the shoes into the slots on the pistons. Make sure you do not damage the piston dust covers in the process. Use a large screwdriver to hook the bottom of the shoes into their respective slots. The bottom of the second shoe requires quite a bit of force.
Bleeding