Sw-em service notes electricity outage compensation


Doing a road test goes back to not having a dyne at my disposal…and this technique is my own and based on my experience (with a number of stock and performance moded 122s and 1800s)…appreciate that it is tricky to relate and that everyone’s experience, and car is different… having stated my disclaimers, I’ll try to explain my technique…

I find that once idle has been set (once off choke and fully warmed up), blipping the throttle should result in a decent response and rise in the revs…(in this case the engine is working against rotational inertia load only…the best I can do without a dyne and parked, so there’s also no need to hold it at high revs…Important – the point is: The info is gained while getting to high revs, not by holding it there!). [A car with a lightened flywheel would respond faster, etc.] While doing this test, a lean condition will cause a

noticeable delay ) and bogging, and possibly even a lean backfire…and don’t forget, this test is somewhat air temperature influenced…colder air would push the results toward the lean side…makes sense (cold air is denser [huh] and SUs being a constant velocity design have no mechanism for air density compensation)…that’s why I find myself adjusting the jets down three flats for the cold season and back up three flats for the warm season (but other than that, I

satisfactorily performing one) from the lean side, and leave it set to where I get that satisfactory perf….so I won’t cover the rich mixture result too much except to say that if you think you might be rich, back off on the jets in half turn steps, and redo the test…I think you’ll find those

For checking the midrange mixture (probably the most interesting operating condition to me), I’ll take the vehicle out on the road, and at a steady midrange speed, quickly floor the throttle (this is probably the maximum load I can put the engine under – up the steepest hill around is even better as it allows a prolonged highload condition…if I get a slow response, that suggests lean again (see above) and I’ll richen both carbs by three flats. Obviously, this assumes ignition (including timing and advance) fuel system (including balance, float height, fuel pressure, metering needle selection, fuel delivery [i.e. no obstruction by sediment in bottom of bowl or some other

weirdness – I’ve seen it!]), and other little details like that are all under control and mixture is the only parameter in question at this point. Once you’re close to being satisfied with the pref., pulling a plug after a prolonged run of a particular operating condition which you want to check,

adjustment business…doesn’t that make a great point for all the things a modern fuel injection/engine management system does for you…sniffing all the temps, pressures/vacuums, your throttle input and whatever else, and looking up and dispensing just the right amount of fuel for each cylinder…most impressive when it works…then again OBDII never got anybody home when something crapped!

positive terminal (by way of the ignition switch and fuse 1) and the generator output terminal. I suggest yours came on full, probably due to a generating system failure, although a blown F1 (or associated terminal or wire) will result in the same symptoms. In addition to checking f1 therefore (which I understand checked OK), you should check its circular contact points, terminals, and terminal connectors, preferably with an ohm meter. The

Finally, I understand you need to put a certain amount of effort into trying to repair the charging system with its original components, but when you are done fiddling around with that genny/relay regulator based system, you should consider the alt/electronic regulator upgrade I developed. A lot of people are very satisfied with the result (see SwEm site). There is additional info in tech articles regarding the dim AMP light you also wrote of.

gauge!….mine have yet to fail, whereas I’d be willing to bet MOST original "Voltage Stabilizers" have died a miserable, electrically violent death long ago (taking gawd knows how many of the instruments with them as well!). I wonder what FMEA (Failure Modes, Effect Analysis) engineer signed of (if any) on that marvel of electrical engineering? [NOT!!] BTW…Was that thing made by Lucas?

cycling between 12 and 0V…and that’s the reason it starts of at 12V…the heating element has just been energized and so has not yet caused the contact to open. This module is located behind the big instruments (held in place by the same thumbscrew which holds on either tach or speedo…don’t recall which). John is right…if they fail in the contact closed mode (12V out), your instruments are doomed! I recommend you loose it, and replace it with a solid state replacement available from

A slow wiper can be caused by among other things, a low voltage to the motor caused by a corroded fuseblock (specifically a voltage drop across F1 and associated connections, which supply the wipers). I suggest you check the voltage to the wipers (engine on, wipers on, at fat red wire at wiper switch). It should be at least 12…better yet 12.5. If low, and caused by fuseblock corrosion, or your AMP light comes on a lot with the blower, it is time for a fuseblock rework!

smooth out readings (as on modern cars (even later Volvos with the infamous Voltage Stabilizers) where you typically have to wait a few minutes after filling the tank for the gauge needle to rise and the full tank to be accurately indicated…or totally electronic cars where you may even need to cycle the ignition for the computer to make a new interrogation of the fuel sender). This causes relatively fast float changes such as fuel sloshing on cornering to be indicated as a bouncing needle.

I actually use this information…occasionally, when I get really low on fuel, I may give the steering wheel a fast flick from side to side…if I see fuel needle bounce indicating slosh, I know I still have a bit left and I’m OK for the moment, but if there is NO bounce at all, I know I better refuel IMMEDIATELY (no offense intended, but women wouldn’t understand, their fuel gauge never drops below 1/2…why is that?). Of course, this effect is