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123 ignition

 
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breninfrance
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Joined: 16 Jan 2012
Posts: 166

PostPosted: Fri Jun 29, 2012 9:27 pm    Post subject: 123 ignition Reply with quote

well my ignition arrived and it's fitted!
I took photo's in case of any questions, but haven't uploaded them cos it's pretty well covered online, any requests and I will upload them.

it was straight forward enough to fit, the hardest part being the removal of the tiny C clip on the end of the points cam (it shot off never to be seen again Rolling Eyes ).

the quality of the product is astounding, anyone who's dealt with classic bikes or cars will know how DIY most electronic kits are, with questionable build quality, and an even worse lifespan.

this is a lovely looking bit of kit, and inspires confidence!


before fitting, I took a moment to view the points distributor in action with the stroboscopic timing light (a nice high quality one with digital advance).

the static timing was a good two degrees out Shocked I know what I'm doing, and had spent a lot of time checking and rechecking the timing statically (I don't own a timing light) and I checked on both cam faces to make sure I had the best possible balance between the two. so I was very surprised to find I was two degrees out Confused

at tickover on points, the timing mark was all over the place, not just wavering, but the odd missfire almost out of view too, as revs picked up, things improved no end, the mark stabilised and missfires weren't visible (doesn't mean they weren't there), but it still tended to drift a little whilst trying to hold a stable RPM, not entirely unexpected, at high speeds the gun shut down (must be a self preservation thing).






123 comparison
I set the timing with the little LED, then fired it up to fine tune it with the timing light, the difference was instant!!!
the timing mark was/is incredibly stable, but very very sensetive to revs, you've got to get the revs right down or the advance curve will kick in and screw it all up, a feature to turn off the advance for timing would be usefull!

I set it up as per the instructions and went for a spin.

straight away it was better, I have to reverse uphill from my drive, and it usually involves a bit of clutch feathering and some throttle pumping, combined with popping farting and flat spots (and that's just me, the car is worse).

very pleased I set off downhill to warm the engine before giving it some, using the same route I use everyday for work, to give as true a representation as possible, the engine was smoother, with extra power pretty much everywhere, and no popping or hesitating anywhere, until, you knew it was coming, until a long straight, where I like to give it the beans, the power just fades out Confused where it used to come "on cam" and get all lively is just gone Shocked Shocked

I took a turn I use reguarley, a long slow twisty climb, and the car slogged up it in fourth quite happily, I would normally be in third and giving it some.

so I took it to the nearest thing I have to a long straight, and at 100kmh the car was all out of puff, and struggling, a serious loss of top end performance Sad


so prefering the performance I had with points, I have set the timing at 10degrees BTDC, and a lot, but not all, of the top end pepp has returned, at the cost of some of the low end grunt, it still maintains its new perfect manners at very low revs though.

any racers on here I'd love to know what timing you run? (just basic starting timing, I'm not asking for race secrets Wink).

and other drivers! road tune isn't the same thing as race tune, what do you lot run??
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dyanut
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Joined: 05 Aug 2007
Posts: 177
Location: North Yorkshire

PostPosted: Fri Jun 29, 2012 11:35 pm    Post subject: Re: 123 ignition Reply with quote

bren,
I don't think I've ever read a better endorsement of what I've been telling A series owners for the last 30 years, which is that setting the ignition timing statically only guarantees that it will be in the correct zone at tickover.
To get the best out of your engine, the timing should be set dynamically, with the emphasis on getting it right at full advance.
For an A series engine with 8.5:1 CR and using 95 octane fuel, between 32* & 35* seems to work well, with 9.0:1 engines needing a few degrees less.

To save on typing time, here's a link to some advice notes I did about 15 years ago...
http://www.flickr.com/photos/30132857@N06/3732492655/in/photostream/lightbox/
... and a video for illustration purposes.
http://www.flickr.com/photos/30132857@N06/5449076261/in/photostream

Road or race, the same principle applies when optimising timing, keep advancing the timing in small increments until the onset of pinking, then back it off a few degrees.

Ken
( p.s. I've lost track of which setup you're using as regards carburation, but is it possible that the mixture is on the lean side?
If you've been experiencing spitting back and misfiring in summer temperatures, things are going to be worse when the ambient temperature is lower. )





breninfrance wrote:

any racers on here I'd love to know what timing you run? (just basic starting timing, I'm not asking for race secrets Wink).
and other drivers! road tune isn't the same thing as race tune, what do you lot run??
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breninfrance
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Joined: 16 Jan 2012
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PostPosted: Sat Jun 30, 2012 8:42 am    Post subject: Reply with quote

thanks dyanut,

I may well be running lean, I have one of the later solex twin chokes with the two tickover screws that are supposd to be balanced with a Co meter (which I don't have). also running a power tube.

the problem is the height, I'm over 700 metres above sea level, and I know from tuning my AMAL carb on my bullet that jets reccomended for just above sea level run way too rich up here

one advantage of the 123 is that it has an exact digital advance, of 20.6 degrees at 3000rpm and 26degrees at 5000rpm.

so adding the static (in my case ten degrees) gives 36, a little high according to your figures, I'm running 9:1 pistons, in fact the static 8 would in theory be perfect, but he revs a lot harder at 10 and shows no signs of pinking.

lots of popping in the exhaust on over-run, but I've put this down to the fact that I'm only running the collector box and an exit pipe at the moment.



I've read your article, and the counted teeth is brilliant, and so logical!!, unfortunately the timing gun is the works one, with a digital display, where you can add the degrees required if you only know tdc. but it stops flashing above 2000rpm, so I have to rely on the 123 figures being correct.
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Bart
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Joined: 17 Jun 2007
Posts: 781
Location: Södertälje

PostPosted: Sat Jun 30, 2012 10:40 am    Post subject: Reply with quote

Hi Bren,
I am not so sure about the height +700m being an issue. I have lambda sensors in my car but didn't find the engine to run richer at +1000m above sea level during holidays, although jets were set up in the NL... Only at higher altitude low idle speed (and probabably overall power) drops because of the lower air density.

For the rest I can only confirme Ken's timing advice works on my car and do yourself a favor and get or borrow a universal timing light/scope and check teh advance at higher speeds, otherwise you are only guessing.

Good luck, Bart
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dyanut
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Joined: 05 Aug 2007
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Location: North Yorkshire

PostPosted: Sat Jun 30, 2012 11:25 am    Post subject: Reply with quote

Bren,
the tendency of an engine to pink/detonate is greatest at the rpm when peak cylinder filling/peak torque occurs, which is 3,750rpm for a standard late 602 engine.
Because 123's various advance curves are shallower than that produced by the original centrifugal mechanism, there is less tendency for pinking in mid-range, however high-speed detonation (which is more difficult to detect from the driver's seat) does become a possibility.
I've sent one unit back to Albert, as straight out of the box it had a total crankshaft advance of only 15*.
It was reprogrammed and returned at no charge, but the fault would not have been found without use of a strobe.
Lightning rarely strikes twice in the same place, but always best to check.

Seems like there's not much change needed in jetting at 700m altitude, not like the Swiss WM in '92 at over 2,000m, where some happy campers were driving around with their air filter element stuck on the front bumper over-rider. http://www.ultralightnews.ca/rotax503/rotax2strokepdf/mainjetcorrectionchart.pdf

An 'old school' motorcycle engine tuning article commented about the tendency for folk to use jetting which is too lean and too much ignition advance when setting up an engine, as the combination can make the engine feel 'crisper' during relatively short test runs.
Have been caught with this myself at Mondello in the early days, having to pull the car in to retard the ignition when, after the first hour on the track, we could hear it pinking every time it passed the pit lane... Wink

Ken.
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breninfrance
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PostPosted: Thu Jul 12, 2012 7:36 pm    Post subject: Reply with quote

thanks Ken.
it was bugging me, I was constantly listening for pinking, rather than enjoying my car, so I hassled around for a basic timing light, and it goes to show, if it don't feel right, it probably aint!

I used your seven tooth count system, and set up on the 8 degrees static, I was almost a full tooth out at anything above 4000rpm (it don't half rev without the fan!!, a blip of the throttle sees 7000rpm, on the first choke Shocked ).

I've not driven it yet, but I don't expect much difference from my setting by feel as the timing light shows it settling at around 9 degrees at tickover.

I have one weird anomaly Confused I've driven it for miles without trouble, but every time I've tried to time it at 8 degrees, the idle jet has blocked!! Shocked
once would be coincidence, but it has happened four times??, I know 100% it's the jet, I can see it's blocked, I blow it out, and it ticks over perfect, (drained fuel tank/new fuel lines/fuel filter/stripped cleaned carb), it's a bizarre anomaly, not that it's difficult to clean the jet, but it's a bit weird??
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dyanut
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PostPosted: Thu Jul 12, 2012 8:36 pm    Post subject: Reply with quote

bren,
shutting the throttle at 'redline + 500 rpm' would put high manifold vacuum on the idle circuit, maybe enough to hoover up any debris
which had been lurking in the drillings which feed it... Laughing

However, it might be worth opening up the fuel pump, as there's a settling area behind the cover where deposits collect.
It's often the case that a high speed run will dislodge some of that, with the finer elements passing through the gauze filter on the carb inlet.
I always clean the pump out when recommissioning an engine, then fit an in-line filter on the chassis leg, where Citroen used a piece of rusty pipe.

Ken




breninfrance wrote:
thanks Ken.
it was bugging me, I was constantly listening for pinking, rather than enjoying my car, so I hassled around for a basic timing light, and it goes to show, if it don't feel right, it probably aint!

I used your seven tooth count system, and set up on the 8 degrees static, I was almost a full tooth out at anything above 4000rpm (it don't half rev without the fan!!, a blip of the throttle sees 7000rpm, on the first choke Shocked ).

I've not driven it yet, but I don't expect much difference from my setting by feel as the timing light shows it settling at around 9 degrees at tickover.

I have one weird anomaly Confused I've driven it for miles without trouble, but every time I've tried to time it at 8 degrees, the idle jet has blocked!! Shocked
once would be coincidence, but it has happened four times??, I know 100% it's the jet, I can see it's blocked, I blow it out, and it ticks over perfect, (drained fuel tank/new fuel lines/fuel filter/stripped cleaned carb), it's a bizarre anomaly, not that it's difficult to clean the jet, but it's a bit weird??
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breninfrance
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PostPosted: Thu Jul 12, 2012 10:24 pm    Post subject: Reply with quote

Shocked that sounds exactly where my filter is, tucked in where the right wing sits on the chassis, I have a 90 degree filter, so it forms the bend/corner lovely, I shall resist stripping the fuel pump for now, as I not only don't have a spare, but I also have no spare car at the moment, so if I tear the diaphragm, then I'm furked!! Confused
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