240 General: New (to me) 1980 Volvo 244

[Stephen Edwin]

Originally Posted by Othen

Whilst I know the intentions were all good, I don't really need people telling me to change belts, hoses, plugs and so on when I either know or can see they are perfectly fine.

Always paddle your own canoe ....



.

[Othen]

In order to check the veracity of the Royal Barge's tachometer I've ordered one of these:



It looks simple enough, and for under a tenner is worth a punt.

[Othen]

Originally Posted by Stephen Edwin

Always paddle your own canoe ....



.

I don't own a canoe.

[Laird Scooby]

Originally Posted by Othen

In order to check the veracity of the Royal Barge's tachometer I've ordered one of these:



It looks simple enough, and for under a tenner is worth a punt.

That looks a useful bit of kit for less than an Ayrton Alan - have you got a link please?

I've got an old AVO branded digital automotive multimeter that was originally about £400 when new from RS plus the genuine leather case (another £80~) that i sometimes use but that needs connections to be made.

Fine for idle speed adjustments when there's no OE tacho in the car and similar but for a quick check or on something that doesn't have an electrical impulse to measure, it's a chocolate teapot.

Originally Posted by Othen

I don't own a canoe.

No, just a barge............

[Othen]

Originally Posted by Laird Scooby

That looks a useful bit of kit for less than an Ayrton Alan - have you got a link please?

I've got an old AVO branded digital automotive multimeter that was originally about £400 when new from RS plus the genuine leather case (another £80~) that i sometimes use but that needs connections to be made.

Fine for idle speed adjustments when there's no OE tacho in the car and similar but for a quick check or on something that doesn't have an electrical impulse to measure, it's a chocolate teapot.

No, just a barge............

Hi Dave,

Yes, of course:

https://www.ebay.co.uk/itm/LCD-Digit...53.m2749.l2649

It would appear to work by sensing a little bit of reflective tape (comes with it) that one sticks on the rotating part (I'm thinking one of the bottom pulleys).

It it works for under a tenner than I'd be pretty happy with it as a one use item, but I think there might be lots of uses for something like this and it might live in my box of useful but rarely used instruments (digital micrometer, dial gauge, IR thermometer, inductance clamp ammeter, Ed 17 multi-tester...).

I've tried a few different add on tachometers in the past (mostly the inductance type on motorbikes) without a huge amount of success, the back EMF tends to make them very slow to react and they are not accurate at all.

PS. Very good about the canoe/barge :-)

[Laird Scooby]

Thanks Alan, i've used them a fair bit over the years but when i last looked, they were upwards of £80 from RS and i couldn't justify the expense purely for my own use.

Reckon you had the last one from your listing, it said sold out when i tried but found an identical one for a similar price so have aded it to my Watch list.

The reflective tape is right but i have also used Tipp-Ex if/when i've run out of it, usually they come with a small reel of reflective tape. Can't find any reels of relfective tape on fleabay at the moment, maybe i'm using the wrong search wrods, i'll have another go later.

[Othen]

Originally Posted by Laird Scooby

Thanks Alan, i've used them a fair bit over the years but when i last looked, they were upwards of £80 from RS and i couldn't justify the expense purely for my own use.

Reckon you had the last one from your listing, it said sold out when i tried but found an identical one for a similar price so have aded it to my Watch list.

The reflective tape is right but i have also used Tipp-Ex if/when i've run out of it, usually they come with a small reel of reflective tape. Can't find any reels of relfective tape on fleabay at the moment, maybe i'm using the wrong search wrods, i'll have another go later.

I think there were a number of different sellers of what appeared to be the same product - all from around Manchester (perhaps it will turn out to be the Manchester in China?).

I was thinking it might well pick up the little bit of white paint I put on the pulley timing mark when I checked the ignition timing. I'll try that first, and if not it should not be too hard to put a square of the reflective on the steering pump pulley, it only has to stay there for 5 minutes while I check the idle speed.

I know I'm being a bit obsessive about the idle speed, I'm pretty sure it is spot on as it is and the analogue display of the tachometer is just reading a bit fast (100 RPM could easily be a parallax error, or maybe just not a very accurate instrument). The lock down means I have plenty of time for trivial things like this that I might normally have never got round to. I like clever tools, and I think this one will be useful here and there - and the cost is such that it hardly matters.

Just recently I bought myself a 'smart multimeter' (means it automatically detects what I'm trying to measure - potential difference, impedance or capacitance diode detection, whether AC or DC); it even has a little torch built in like a cell phone. In fact I've just had a look at the little Chinese/English instruction book and notice I measures frequency as well - so I could probably get it to measure the idle speed at the coil! Anyway, the point is it cost about $10, and once I'd put two new batteries (remote locking type) it is genuinely useful. We are so spoiled wit cheap but pretty good tools and instruments these days.

Alan

[Laird Scooby]

Originally Posted by Othen

I think there were a number of different sellers of what appeared to be the same product - all from around Manchester (perhaps it will turn out to be the Manchester in China?).

I was thinking it might well pick up the little bit of white paint I put on the pulley timing mark when I checked the ignition timing. I'll try that first, and if not it should not be too hard to put a square of the reflective on the steering pump pulley, it only has to stay there for 5 minutes while I check the idle speed.

I know I'm being a bit obsessive about the idle speed, I'm pretty sure it is spot on as it is and the analogue display of the tachometer is just reading a bit fast (100 RPM could easily be a parallax error, or maybe just not a very accurate instrument). The lock down means I have plenty of time for trivial things like this that I might normally have never got round to. I like clever tools, and I think this one will be useful here and there - and the cost is such that it hardly matters.

Just recently I bought myself a 'smart multimeter' (means it automatically detects what I'm trying to measure - potential difference, impedance or capacitance diode detection, whether AC or DC); it even has a little torch built in like a cell phone. In fact I've just had a look at the little Chinese/English instruction book and notice I measures frequency as well - so I could probably get it to measure the idle speed at the coil! Anyway, the point is it cost about $10, and once I'd put two new batteries (remote locking type) it is genuinely useful. We are so spoiled wit cheap but pretty good tools and instruments these days.

Alan

Unless the PAS pully is the same size as the crank pulley, you'll have to measure it at the crank pulley Alan. As it's fairly dark down there, it will probably pick up the white spot for the timing, i know the one i used did.

If you do measure the frequency at the coil on the -ve terminal, 20Hz will be 600rpm if my mental 'rithmetic is right at the moment.

600rpm = 10 revs/sec, 2 ignition pulses per rev on a 4-stroke, 4-cylinder = 20 pulses per second = 20 Hz.
Therefore 900rpm will be 30Hz, 750rpm 25Hz etc. I know many Volvo speedos read 10+% fast once they're older due to a calibration resistor going out of tolerance, seems reasonable to expect similar from the tacho.

I know sometimes when i've used my AVO meter to check rpm, it's read lower or higher than the on-board tacho so never been sure what's what.

All this reminds me i must investigate and repair my Gunsons Gastester - purely on a mechanical basis, the black box on the back containing the thermistors for sensing the CO content has parted company with the main case (only glued/taped on originally) so i need a more permanent fix than the trim tape i tried.

[Othen]

Originally Posted by Laird Scooby

Unless the PAS pully is the same size as the crank pulley, you'll have to measure it at the crank pulley Alan. As it's fairly dark down there, it will probably pick up the white spot for the timing, i know the one i used did.

If you do measure the frequency at the coil on the -ve terminal, 20Hz will be 600rpm if my mental 'rithmetic is right at the moment.

600rpm = 10 revs/sec, 2 ignition pulses per rev on a 4-stroke, 4-cylinder = 20 pulses per second = 20 Hz.
Therefore 900rpm will be 30Hz, 750rpm 25Hz etc. I know many Volvo speedos read 10+% fast once they're older due to a calibration resistor going out of tolerance, seems reasonable to expect similar from the tacho.

I know sometimes when i've used my AVO meter to check rpm, it's read lower or higher than the on-board tacho so never been sure what's what.

All this reminds me i must investigate and repair my Gunsons Gastester - purely on a mechanical basis, the black box on the back containing the thermistors for sensing the CO content has parted company with the main case (only glued/taped on originally) so i need a more permanent fix than the trim tape i tried.

I wasn't very clear there Dave, I meant crank pulley end of the PAS, not the pump end. The timing mark I painted white (with an Airfix brush) shows up quite well, so I'm hoping I will be able to focus the gizmo on that. There is no fan getting in the way on the Royal Barge, which should be an advantage.

Our last posts crossed in the ether - while you were typing I took the smart meter out and tried it on the -ve side of the coil, but unfortunately that didn't work. I think the instrument is looking for a sine wave rather than two blips per revolution to give a frequency reading (it works fine at 50Hz mains).

I'm thinking I could devise some means of calibrating the hand-held tachometer - I'd just need a mechanical device rotating at a known speed or one I could measure. It claims to read down to 2Hz, so I could probably use something like a fan on a really slow setting against a stopwatch. 900 RPM at the pulley is then 15Hz, so I'd only have to extrapolate up by a factor of less than 10. I'm thinking that if I could measure something at say 4Hz (a fan or small electric motor) I could scale it up to get a pretty good estimate of the engine speed at about 900 RPM.

... the Coronavirus lock down has a lot of trivia to be responsible for!

[Laird Scooby]

Originally Posted by Othen

I wasn't very clear there Dave, I meant crank pulley end of the PAS, not the pump end. The timing mark I painted white (with an Airfix brush) shows up quite well, so I'm hoping I will be able to focus the gizmo on that. There is no fan getting in the way on the Royal Barge, which should be an advantage.

Our last posts crossed in the ether - while you were typing I took the smart meter out and tried it on the -ve side of the coil, but unfortunately that didn't work. I think the instrument is looking for a sine wave rather than two blips per revolution to give a frequency reading (it works fine at 50Hz mains).

I'm thinking I could devise some means of calibrating the hand-held tachometer - I'd just need a mechanical device rotating at a known speed or one I could measure. It claims to read down to 2Hz, so I could probably use something like a fan on a really slow setting against a stopwatch. 900 RPM at the pulley is then 15Hz, so I'd only have to extrapolate up by a factor of less than 10. I'm thinking that if I could measure something at say 4Hz (a fan or small electric motor) I could scale it up to get a pretty good estimate of the engine speed at about 900 RPM.

... the Coronavirus lock down has a lot of trivia to be responsible for!

Sorry this one is short, not feeling too godd at the moent.

Record deck @ 45rpm, put multiple pieces of tape at equal spaces round the dege to get your lower end. Four pieces of tape would give you 180rpm or 3Hz.

Yes, the drive pulley for the PAS is still part of the crank pulley so would be fine