123 Ignition system on Volvo1800S

[tsetse1986]

Originally Posted by Wulff

I have a standard 123 fitted to my GT with original taco (and a B20 twin carb) and works absolutely perfect and without any modifications at all.

Also have it on my 1800ES with B20E and likewise works excellent and in both cases with zero maintenance. A really good buy.

Cheers

John

That is interesting and unexpected John. The original GTI tacho is a Smiths RVI current pulse type which are identified on the 123 ign website Q&A as being incompatible with 123 ignitions. The reason for this is very likely that the current pulses from the ignition system are different in duration and amplitude between points and electronic systems. This will result in different tacho readings (probably lower) with electronic systems. The tacho will still work but will be out of calibration.

The fix I was thinking of is an additional small box that takes the voltage pulse from the coil and converts it to an appropriate current pulse for the RVI tacho. The advantage should be that this device will adapt any electronic ignition to any RVI tacho with no recalibration or tacho modification. This is just an idea at the moment so will need some development yet!

[asneddon]

I have a 1963 p1800 and a 123tune. Tachometer works perfectly. This is the type of tach with the white wire loop through the clamp at the back if the tach.

You can check the accuracy of the tach by having your laptop with you why revving. I has already drilled a hole in the back of the tach to adjust the movement, and probably tweaked it a little, but can't remember it being massively off.

One if the fantastic features of the 123tune is the ability to give an advance dip at your idle speed. My car use to hunt up or down depending on hear sink etc. now it's a dead stable idle. And that's with leaking carbs (which seems to be one of those jobs I never get around to doing).

[Groundes-Peace]

Asned,
Thanks for your response. Sounds like you are getting some great benefits from your 123. I assume you have the 123Tune. Do you need a special lead to link laptop to the 123 unit?
Am I right in thinking the 123 will be useful in setting up your carbs when you get round to sorting these out?

[asneddon]

The cable is a pretty standard USB one. You have to get one with a pretty small end so it fits through the hole in the side of the body though. Any generic cable will work.

The tune version allows you to fit a switch so you can change between curves on the fly. I have the one I use 99.9% of the time, and a secondary one that's identical except that it doesn't have the dip at idle. I use that's secondary curve for setting the carbs.

My carbs have an air leak around the spindles. I've bought the kit, and even bought a spare set of carbs so I could rebuild them and swap over. I've spent at least a year not doing anything about it though. Actually, I bought the kit when living in the uk. That was 3 years ago! I must get around to it one of these years.

The 123 won't really help with setting the carbs I don't think. Except in such that I can just ignore the ignition side.

I did remember a bit of a downside. You are meant to hook into the ignition switch, but can't because of the armoured coil thing. I just went straight to an always on +ve at the fuse block. The distributor only takes 0.64mA from memory. I figured that's the same as a clock so didn't worry about it. Doesn't seem to be an issue.

[Volvo Canadian]

It sounds like you are receiving lots of positive feedback on the 123T - good! Tachometer issues aside, I hope you get one so we can compare notes. I can send you the files I have.

As I have probably said before, their software interface has some awkward programming. The manual is terse, but correct. There are also a set of videos on utube which are worth watching, if a bit long. On this side of the pond service has been very good, and the units are very reliable. I would ascribe the occasional no-starter to wiring errors, but regardless, they seem quite prompt with sending replacements.

Finally, a rolling road is not essential, and anyway you will probably want to make adjustments after the fact anyway. As long as you have a passenger, this can in theory be done on the fly, but in practice, I'm not sure how easy that would be.

[swedishandgerman]

You're right: a rolling road is not essential. However, to give the most bang for your buck at each point you set the advance throughout the rev range, it would be most useful to get a power output reading off the dynamometer (dunno how to spell that properly!)

Basically, the most powerful combustion happens at just the point before pre-ignition (pinking) occurs. As soon as pre-ignition occurs, power drops off considerably

Based on the above, if you could do a power reading at say 1,000rpm, 2,000rpm, 2,500rpm, 3,000 rpm, 4,500 rpm as well as making an adjustment on the advance at whatever RPM the power peaks at, you know can be sure that the timing is just right

Without a rolling road, you could just check what advance feels about right at given engine speeds and listen out for pinking. If it pinks, turn it back

[asneddon]

There is a setting in the software for setting the timing my measuring the time it takes you to accelerate from a set rev to another set rev. I haven't used it but the theory seems fine.

You have to do it on the same flat bit of road each time obviously.

[Volvo Canadian]

Hi, yes this is right. I've never tuned an engine on a rolling road, but considering the price of the 123T to say nothing of the overall cost of the car, I'd like to try that. I just don't know how closely one can tune it. What is the procedure - measure hp at particular rpm, adjust and repeat? I imagine the method above is less accurate, but don't know. I guess I could peruse the 123 website (they have a fairly active discussion board).

I'd like some comments on the curve I posted somewhere, sometime, somehow in the meantime.

[swedishandgerman]

There's so much you could do if you could get on a rolling road and a dynometer!

Yes - you'd need to choose what engine speeds to plot your points at and take measurements from the dynometer as you make incremental adjustments to your advance settings. The best advance setting would give the highest output

[Volvo Canadian]

Hi. Okay! I had intended on doing that, but I didn't have time before launching on my cross-country trip.

Obviously everything else has to be in tip-top shape before doing something like this. Should be okay - carbs, fuel-pump, filters, head and valves, make sure plugs are clean....

I'm a little shy because it is not like I'm running a race-car or anything; would it be possible to compare high and low-octane fuels too? Just a simple as running the line to a bottle full of the alternate fuel, right? And I guess one just has to go with a happy medium temperature-wise too, eh? (Yes, that was a linguistic slip - "Canadian").