Tick Over / Idling rpm

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Julian B
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Tick Over / Idling rpm

Post by Julian B »

Anyone know what the "ideal" tick over speed should be set at? Should I aim for 800, 900 or 1,000 rpm? And does it matter whether I set it when the engine is cold, warm or hot?

I do have an accurate strobe gun with tacho display, so it should be easy to set it fairly accurately. At the moment my engine is ticking over at ~950rpm when warm, but wonder if this is slightly higher than it need be.

FWIW the red charging light is going out at ~1,200rpm.

Many thanks!

Julian
Julian B
W Sussex, UK

| '62 Early Series I SWB | '72 Series II LWB |
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heinkeljb
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Re: Tick Over / Idling rpm

Post by heinkeljb »

Julian,

Both the repair manual and the operators handbook I have suggest slow running (Idle) speed of 700 RPM and fast idle is at 800 RPM. If your engine is in good condition (compression, no parts worn - carb, oil pump, rings, valves etc) then with a warm engine it should be possible to get an even tick over at 700 RPM.

The problem with this will normally show it self when you try and accelerate from idle (particularly under load) when the engine will "gasp" before picking up revs. It should pick up revs cleanly.
This is normally down to wear in the carb, places where it is difficult to correct. The pre-drilled holes in the carb body for example.

The usually way out of this "hiccup" on acceleration is to increase the revs slightly, so the transition phase in the carb is at a slightly different point. So increasing the revs towards 800 RPM might result in a smoother engine pickup from idle.

Certainly I would be aiming for less than 900 RPM with a hot engine at idle.

The red charge light going out at 1200 RPM seems to be a bit high, but only because the only reference I can find in the repair manual to RPM is 1000 which I believe relates to the "0" voltage point between the dynastart using electricity and it making electricity.

There is a section in the repair manual which explains various tests which you can carry out and how you can alter some of the settings so maybe it can be made to start charging at a slightly lower engine speed.

John
Last edited by heinkeljb on Thu Feb 06, 2014 7:20 am, edited 1 time in total.
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AustHaflinger
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Re: Tick Over / Idling rpm

Post by AustHaflinger »

Hi Julian - basically as John has said - my engine will idle at less than 700rpm but will then stall when coming to a stop at lights etc. 900rpm is Ok but is a bit high and then often the reverse happens - when stopped at lights it goes up to higher revs. The sweet spot does seem to be 800 and it tends to stay within a narrow range of revs in all conditions whether it be hot or cold.

My charging light goes out at about 1200rpm which is a bit annoying but the charging system is strong and easily charges my battery so I have not worried about it.

Cheers

Garry
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Julian B
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Re: Tick Over / Idling rpm

Post by Julian B »

Thanks both - I will try to get it to tick over at 800+/-.

Garry, when you say that your charging system is "strong", how do you determine / measure that? Whilst I always keep the battery fully topped up with an Accumate Smart Charger, I have no idea how well (specifically) the dynastarter charges the battery when in use.
Julian B
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AustHaflinger
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Re: Tick Over / Idling rpm

Post by AustHaflinger »

Julian B wrote:Garry, when you say that your charging system is "strong", how do you determine / measure that?
I have had my Haffie for 16months and never charged the battery (Canberra winters are as cold as the UK) and I do go for drives at night particularly on hot nights so use lights a lot. I have a volt meter on my dash and when driving it shows 14v and even when idling with the charge light on, the battery has always showed over 12.5 volts. I have even had the misfortune to have to crank the haffie off a busy road on the dynastarter (not recommended) and the volt meter was still showing 12.5v. So the generator is keeping the battery well charged even if the light does come on a bit.

I have not yet experienced a low battery even on cold mornings.

Garry
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Re: Tick Over / Idling rpm

Post by heinkeljb »

Julian,

Do you have a multimeter? If not, time to buy one! Obviously charging the battery is a combination of voltage and current. The simplest test is to use the multimeter on the voltage setting. Make sure it will allow 10 to 15 volts to be shown.

Then connect the black negative lead of the meter to the negative terminal of the battery. The red lead of the meter goes to the positive terminal of the battery.

Record the reading (should be around 12.5 volts)

Start the engine, observe the meter reading - it should go up as revs increase but hit a peak at about 13.7 / 14.0 volts.

I have a special meter which allows you to measure the current without having to break in to the circuit. In order to measure the current with your multimeter, some have the ability to measure 10AMPs, you have to disconnect one of the battery leads, put the meter in the circuit by connecting the leads to the battery terminal and the lead going to wiring loom.
10 AMPs is not enough especially during starting! It will blow the fuse or the meter depending on the design. My meter is specially designed to show much higher currents without having to break in tot he circuit. If you want to borrow it, let me know.

Just from the voltage readings you should be able to tell if your Dynastart is charging the battery and at what point it is doing so in relation to the red light going out.

John
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Julian B
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Re: Tick Over / Idling rpm

Post by Julian B »

John,

I have a fairly basic multimeter (like this one), but I only know how to use some of the very basic functions. :oops:

I've just checked my battery (with ignition off & Accumate switched off) and it reads 13.42v. The battery is 12-15 months old, and has spent the vast majority of its life attached to an Accumate.

The instruction book specifications state "Overload Protection: Diode & 250v 0.5A fuse", and in the "DC Current Measurements" section it says "Range ... 2mA, 20mA, 200mA 20A (mA inputs 0.5A/250v fuse; 20A input unfused)". Would it be man enough to check the charging rate? And if so, would I do this with all of the other leads still connected to the battery, or do I still need to disconnect one terminal and put the multimeter in series?

Cheers,

Julian
Julian B
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heinkeljb
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Re: Tick Over / Idling rpm

Post by heinkeljb »

The Dyanastart is rated at 240 watts output: so using the dreaded school electrical formulas (I.E. simplistic calculations) Power = Current x Voltage.

Turning things around gives you: current = power divided by voltage > 240 /12 = 20 (Amps)

That would be near the maximum output from the regulator into a completely flat battery. As yours has a good voltage to start with it is unlikely to draw that sort of current, so you meter should be able to cope with what we are going to ask of it.

The first thing to do is find out the standing current loss and the current when you have various electrical items on. This will help you get the hang of how the cables are to be connected.

First off, every thing off,
Undo the positive connection to the battery.
Attach the positive lead from the meter to it. If you can make a connection system that allows you to leave it connected without having to hold it on to the terminal, that makes things much easier. A longish piece of bare copper wire wrapped round the terminal and then around the probe tip from the meter should do the trick.
Now the negative lead from the meter to the positive lead that went to the battery.
Meter on.
Hopefully you have 0.00 Amps showing.
Now turn on the side lights - this should show (2 x 3 watts front side lights, 2 x 5 watts rear side lights, 1 x 3 watts speedo light, you don't have a fuel gauge on this Hafi do you? if you do then you have to include that in the calculation - 2x3 + 2x5 + 3 = 19 watts:- so using the formula above; 19/12 = 1.583 Amps. So the meter should now be showing numbers very near to 1.6 amps. (Don't fret if the numbers are not exactly that - remember the battery voltage is not exactly 12 volts and there are loses in resistance at the joints etc)
The readings should be - 1.6 Amps as the power is being taken from the battery. If the reading was + 1.6 Amps then we have got the wires on the meter connected the wrong way round - I can never remember which way they should be, but I know I am expecting the reading to be a negative value!

You can add the headlights in now if you want to see what current that circuit uses.

Things get a little bit tricky now, as when the Dynastart is in starting mode it will draw up to 300 Amps which if you hadn't guessed will burn your meter out quite quickly!
The way round this is by having two people. one is going to do the standard starting sequence, the second has the cables from the meter to deal with.
You start by having every thing off of course.
Take the same setup as you had above with the meter connected in series with the battery cables. Take the positive cable (still with the meter wire connected to it) and touch it to the battery positive terminal - You have now "shorted out" the meter from the circuit.
Start the engine - the huge current will flow across the easy metal to metal path and not through the meter as the meter wire go the same place so there is no difference in voltage between the two meter cables.
Once the engine has started and the Dynastart has become a generator, you can "separate" the battery terminal and its original wire so the current has to go through the meter. There is no interruption of electricity so you should not have any strange hiccups or possible bad things happening to the engine or Dynastart.

You should now have a reading on your meter - if it has gone beyond 20 - then it will have blown the meter as your meter has an "unfused" 20 Amp setting. In which case it will show 0 or 1 and it will not change.
If everything has gone according to plan you will have a figure showing the charging current going into the battery. If the number is negative then we have the wires connected the wrong way - see above. With your digital meter this is not really a problem as it will show negative numbers as well as it shows positive numbers. With the old needle based meters more of a problem - which is why the ammeters you see in cars have both positive and negative sides for the needle to move to!

Anyway, to get back to your issue. with the engine running your figure should change as the engine revs go up and down. Hopefully not by a lot.

Remember we measured the current used by your side lights right at the beginning? The figure you are seeing now should be higher than that and if you turn the side lights on now, you should still see a reading which shows that the Dynastart is putting power INTO the battery. If the value changes from positive to negative (or the other way round) when you turn on the side lights, then you have a PROBLEM! :shock:

I'll leave the answer to that for another post if needed - this is long enough. :)
Last edited by heinkeljb on Sat Feb 08, 2014 10:32 am, edited 2 times in total.
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Re: Tick Over / Idling rpm

Post by AustHaflinger »

Julian - do you think you actually have an issue? From what you have described you only seem to be concerned about the 1200rpm being the point that the charging light goes out - remembering it is a generator and not an alternator so as a general statement the faster it revs to more it generates. My light turns off at the same revs and I have no issue.

I know through personal experience that it is easy to go looking for things when there is nothing there - so unless you do have something that does indicate a charging issue then I would be tempted to leave things as they are - after all if something does show up the relevant parts are easy to get at.

The other thing is that when driving a haffie around it is normally full on so the only time the engine gets down to around 1200rpm is when coming to a stop and taking off.

I am lucky having a volt meter on the dash so can see at a glance what is going on - if I was you I would just run the car when you actually get it on the road and occasionally just check the voltage across the battery when stopped and as long as it remains above about 12.5v everything is fine. If all Ok then just drive and enjoy.

Garry
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Range Rover Sport TDV6 (07)
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Landrover Series 1 SWB Station Wagon (57)
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heinkeljb
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Re: Tick Over / Idling rpm

Post by heinkeljb »

I agree.

It is nice to know that your electrical system is correctly setup, but other than you doing a set of replacement wires. You didn't do anything to the regulator box did you?

The point of zero EMF (the point the light goes out) in relation to engine rev's will be higher in a dynamo system than in an alternator system. The reason modern cars all have alternators!

I presume the engine starts easy enough, in other words the Dynastart can turn it over without struggling? If yes, then the starter solenoid part of the system is working correctly. Sticking a meter set to volts across the battery terminals and noting the voltage with engine off, engine on and when engine is reving beyond idle will generally tell you if things are alright.

John
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Julian B
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Re: Tick Over / Idling rpm

Post by Julian B »

John, my head hurts just reading that! But thanks for posting it and I have printed it off and will have a play with my meter over the next few days.

Garry - you are right, and I have some more pressing issues to resolve first ... like being able to engage reverse!

Will let you all know how I get on ...


[UPDATED TO ADD ... John, yes the engine turns over on the starter nicely, and fires up quickly]
Julian B
W Sussex, UK

| '62 Early Series I SWB | '72 Series II LWB |
| '56 Citroën Traction Avant |
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