first Land Rover????

[redhawk8391]

Gregor:
Thank you for the info re the diff. I should have the tool you described (if I can find it ) left over from the days when L/R was a full time thing. I am reserving judgement on the prop shaft until I can drive the vehicle. It seems ok, but a cfm is in order. I have removed the spk plugs. They are gapped at .035 . My spec sheet says .025 for the 24V. Who had it right?
It was interesting to read the many comments re the 24V-12V voltage reduction. The use of diodes and a heat sink etc. would be the way I would expect a "solid state" device to be constructed, but finding the components around here will get you a little more than a "peculiar look" and the question what do you want that for? Will try the address provided by Sheldon. If one examines the principle by which a charging system works, it is obvious that tapping one of the 12's is not going to work unless you have a shed full of batteries.
David

[greenmeanie]

David,
.035 sounds like it used the 12V set up. .025 would make sense although I don’t have my manuals here to check it.

A simple explanation.:
The ignition system is designed to make a spark at a set time relative to piston motion in order to initiate combustion. The timing of this spark is controlled by the position of the dizzy and its amperage. (Ability to build potential on the plug electrode.) If you still run points then there are some other factors such as points gap and dwell that have an effect. The spark will jump the gap when the potential exceeds the dielectric (Air gap). This potential has to be rebuilt every two engine revolutions in a 4 stroke cycle. The amperage of the dizzy dictates how quickly the potential can be built. A 24V system has lower amperage than a 12V so takes longer. In order to have the spark jump at the right time you close the gap so that less potential is required. I am no expert on combustion but it is my understanding that it is spark intensity and not size that is the important thing so the actual gap being reduced does not less performance. Someone will no doubt chime in with more detail/better explanation.

Having said all that if it is working and emissions are good I wouldn't mess with it. The last 5 minute tune up I did turned into a 1 1/2 year rebuild. Damn the shipfitter's disease. Still it does mean that I have her stripped down to the roll hoop and spare while I bed the engine in. The 101 is the most fun convertible I've ever driven.

The beauty of converting to a 12V system is that you can ditch the points and ballast resistor and replace them with an electronic ignition and sport coil. I say this only because I have not seen a 24V equivalent. This gives an almost maintenance free system (rotor and cap occasionally) with a more consistent spark as there is no mechanical wear/adjustment in the points. In theory you will have a faster ramping system with the ability to develop more potential in a shorter time thus allowing you to increase the air gap for a fatter spark and higher performance. In reality we are driving an army truck so any gain here most likely is not noticeable. I keep mine at the stock setting.

Contrary to some opinions electronic ignition is reliable. There is some infant mortality due to manufacturing errors but, generally, if it works in the beginning it will work for a long time. For justification, look at the number of posts regarding issues with points ignition vs electronic.

Cheers
Gregor

[redhawk8391]

Gregor

Thanks for the tech explanation. Very interesting. I am wondering if it is feasible to use a 24 - 12 V converter for ignition. There is a formula which I have lost long ago. I would like to "ditch" the breaker points, they were definitely a problem. Most likely the best solution is to do this simultaneously with the full conv to 12V. I removed the plugs to check their condition and look for telltale signs of head problems. The carbs were in sad shape - I had the feeling they were being removed for the first time since assembly at new. The air filter is a dinosaur - looks like something from a tractor.
I saw a 12-24V convertor on the net with a capacity of 700 watts for $99. Am wondering about the capacity of the black box described by Erin. The device described by Pieco appears to be the easiest way to go, although I would need to know the design of the heat sink.
What did you find of significance when you stripped your engine? I have cracked exhaust manifolds - same area both sides.
TTLY
David

[greenmeanie]

The significant things I found on my engine strip were:

• The cam was almost round. The truck ran well enough and I had not noticed the performance dropping but that's because it was a very gradual thing over time. The faces of the tappets were fatigued as well. It still sounded fine but the entire valve train was shot.
  The main and big end bearings were shot with the copper colour showing.
  The cylinder bores were smooth with just a slight lip. I had them bored .020 over and honed.
  The valve seats were pretty worn but were easily brought back up to snuff by the machine shop. The valves themselves were good although the inlets did have a significant amount of encrustation although this was probably due to the worn cam preventing correct breathing.
• The timing chain looked OK but I replaced it with a JP set anyway as I was going that deep.
• I have not cracked the manifolds yet. I put in the dicsovery metal exhaust manifold gaskets which seal well, used the funny metal tabs on the bolts and made sure I use the correct torque. It has been successful so far.
• My carbs were fine beacuse I have been in there before several times as I have to pass emissions in Phoenix.
• The radiator was pretty much shot with signs of leakage along the bottom where the tubes meet the header tanks. I had had problem with cooling in the summer (It DOES get to 118°F) so pulled it and had it recored. It cools very well now.
• The radiator bottom hoses were completely shot. They were swollen and had fine cracks all over. I don't think they would have made another summer.
• The fuel filters were not bad at all for the age of the vehcile. I have since had to replace them twice in one tank full due to buying 13 gallons of fuel with a special on 2 gallons of silt.
• The head gaskets (tin type) did not appear to be leaking but there might have been a little evidence of blowby into the valley. When I rebuilt her I used composite gaskets (Skimmed the heads to maintain compression) and left off the outer row of head bolts per the advice of several of the UK specialists.

That's about it. Incidently I checked the manual at the weekend and the spark gap is the same for vboth 12V & 24V at .025" so some of my first prargraph of explanation was wrong. The principle of operation, however, is correct. The more modern plugs have some advances such as copper electrodes etc. which allow for better performace. The comment about the electronic ignition is still true.

Cheers
Gregor

[redhawk8391]

Gregor -

Your 5 minute tune-up was extensive! This is excellent info - gives me an insight into what to look for and/or expect. Can you tell me how many miles (or kilometers) were on your "clock" at the time? Am still sitting on the fence, but am leaning toward the conversion to 12V, which means more questions. Is this done piece meal (with ref to the ign system). Do I require a different distributer? Are those small (fuel) filter elements available as an after-market item? Am also wondering about the fuel (leaded or unleaded) intended for this engine. The cracked manifolds sometimes indicate this. I don't know exactly what year the fuel here became unleaded. My vehicle is a 77. You had mentioned emissions testing. I do not see any pollution controls or devices of any kind on the engine. What is the test based upon? The regulations here are different.
Thanks
David
btw - due to the tech nature of some of my posts, and I am new to forums, should I have started a new thread or is posting here ok?