Exhaust note - 123Ignition

When I first started the roadster after the 123 installation, I immediately noticed a throatier, deeper sound from the exhaust. I was sure it was my imagination but a friend standing by noted it as well. Last Month’s issue (July) of The XK Gazette has a very enjoyable article by Stuart Norman, and the upgrades that he has done to his 120 OTS. In it he says the car “sounded different” also.

Just curious, has anyone else noticed that, and I’m not sure why an electronic ignition (hotter spark?) would create a deeper exhaust note ? Perhaps the fact that I have a single, SS, exhaust is a factor, and that a difference might not be noticeable with a dual system (?? )
Cheers, and stay well, Knight

Most likely that the ignition timing is different?

Hi Nick. When I strobed the timing after dialing it in, it ended up very close to where it was before. I know the spark is miles hotter than it was before, which is why the 123ignition suggest increasing the spark plug gap. The first time I saw the power of the spark at the plug with my spark gauge after installation, I was astounded. Stay well,

I have a 123 in two Jags. If you installed a new coil you might have a hotter spark and certainly have a different advance curve than a tired old dissy. My XK140mc needed a slightly colder plug - B7ES and runs extremely well. My 4.2L runs well with slightly cooler BP6ES and does sound more aggressive than with the stock dissy - which was original and worn. The great thing is both cars run much better!

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Knight,

Not an expert in “soundwaves” but I can imaging that having a better internal combustion (let’s say “explosion”) will increase the amplitude of the soundwave, thus creating a different sound or tone.

Bob K.

Ill tell you what happened to my new rebuild etype 4.2…
The 123 is so on target and so smooth that yes the sound is very fluid and even, but , On a cool day at around 1,500 rpm you think the car stalled it was so smooth and even!
For everyone who does not believe…oh well, for the drivers, ITS THE BEST DAMN DIZZY FOR THE MONEY WITHOUT THE ISSUES!
GTJOEY1314

Joey, I couldn’t agree more !
I had gone through my original distributor and truly felt that the car was running at its best then. In fact, I wasn’t putting in a 123 to fix anything, or looking to improve the car’s running except that it would reduce maintenance of changing, and adjusting points, and I liked the idea of being able to select different advance curves. So I wasn’t prepared for the drastic change ! Its a pretty dramatic improvement on how smooth the car runs, how quickly it starts, and the acceleration is so much more consistent.
I haven’t really played around with the advance curve settings. Before I put it in, I wrote down the advances on my car at various RPMs, and then matched that with the chart. That came out to setting #8 on the dial.
I have noticed that the difference in quality of gas is more noticeable with the 123. Around town, I always put non-ethanol gas in at our local station, but lately I’ve had to gas up on the road, at stations that don’t have non-ethanol gas. I can feel the difference now whereas it was not very noticeable before. Thanks and stay well, Knight

Great write up
Yes again for the non believers of ethanol
It’s so dramatic in hot weather and the 123
Where the 123 shines is when your doing around 40mph then punch it to get on a highway or something it just pulls like a freight train!
I just loaded the car with cam2 100 octane you thought I converted to electric it’s so quiet
Enjoy the ride!
Gtjoey13-4

I’m looking into the 123 for my XK140 MC. Which model did you all select and why? Standard? USB port? Bluetooth?

Thanks!
Chet

Chet, I purchased the standard 123 for a negative ground car. I just like things simple, and I don’t find myself in a variety of driving conditions. If I were rallying hard, then combining that with different street driving conditions, or perhaps traveling through different countries, like the XK-ers in Europe & UK, with different fuels available, then I might have felt a need for more frequent adjustments. I basically drive the mountains of North Carolina and do very light (cocktail) rallies. ;-)) Maybe on the next one, I’ll get a USB unit but I’m just not that great at using my iphone in that kind of capacity… I’m a dinosaur. I hope this helps, Knight

Do the bluetooth and USB work with a positive ground vehicle?

I’m pretty sure yes, if you order for a positive ground car.

I have the 123 Bluetooth vacuum version on my + positive earth XK120.