BIS ignition timing opinions (and cold starting)

[Lewey]

What are people's opinions on the best strategy for the timing the Bis engine.  By this I mean figures that you use.  I have it as per the manual at the moment - 10 degrees BTDC.  As I am using 95 RON fuel instead of the manuals' quoted 100 RON, I thought perhaps a retard of 5 degrees is appropriate for example.

What are peoples' experiences and thoughts- do you just advance until it starts to pink(!) to get the best performance- (this seems to work a treat with my Land Rover for example).

I find my Bis is increadibly hard to start when cold by the way- can they be made to start on the key, or are they just not great whatever the tune of the engine?

[PaulB]

Spot on timing will help cold starting a lot, as will getting the idle mix right.

I use static timing as you do, but usually fine adjust by ear - make sure the engine is hot and choke is off before doing this.

Cold starting is partly a problem because batteries become much less effective when cold. Electronic ignition does better with less power so that's one option.

Another problem is fuel condensing in a very cold carb - not a lot can be done about that. Another is damp. When points/caps were common, you'd often see people putting sheets of newspaper in the engine compartment as insulation at night, and then see cars catch on fire in the morning when the forgot to take it out - especially aircoolers. Keeping the car in a garage, under a carport or even under a cover should help starting as it helps keep out the damp and cold

Having the engine too advanced has the opposite effect and hot starting becomes a problem. I just listen for that 'sweet spot' where the engine isn't racing but is running at its smoothest. Static timing using a 12V test bulb instead of by eye (for the points) can make a huge difference too. I think the BIS has twin coil - that helps too as you get an effective over-boost at starting due to the ballast resistor set-up.

Needless to say, keeping the whole ignition system in top condition helps - leads, plugs, etc, and clean connections right through from the battery to starter to engine.

[Lewey]

Thanks for the comments.  I agree with you about covering the engine and damp and so forth, but it is not practical for me at the moment to shelter the car much as I already have a full garage, a blanket is something I could try though..

I use the bulb technique when starting the timing process, but find a timing gun is better once the engine is going of course.  At the moment I find keeping the engine at good operating temperature is difficult.  I have had a modified thermostat from purchase that I assume must open very early as a precaution against the dreaded overheating/ gasket probelms the car has.  This means unless I am at full throttle for many minutes, the temp gauge never goes near mid point.  When I get back to my garage, I have to be quick to tune her before she requires encouragment to idle smoothly again.  Talk about overcooling!

I will wait to see what others suggest, but I think I will throw the book out the window and do it the old fashion way as you suggest- by ear.  Which should I adjust first: the igntion or the idle mixture.  I appreciate one will affect the other, but I never know with the 126- get the idle mixture spot on, then fine tune the timing or vice versa?

My cold starting symptom is that the engine fires immediately, but fails to revolve fast enough to idle.  This means keeping it on the starter motor for up to 20 seconds, even on full choke and normally a little gas to boot.  Imagine "Bang, Bang, Bang, Bang, Bang, Bang" getting faster and faster until it surpases the starter motors capabilities in revolving the engine.  When it finally goes, the idle will be very high and I immediately have to lower the choke to half way, where it will stay for most of my short journeys because of the overcooling problem.

[Chris Lakin]

hi lewey, you dont wnat the choke on that long!!!!

cant be any good?

chris

[Lewey]

When I say short journeys, I mean a mile with roundabouts and bits that I will stall at if it isn't at least up a bit.  If I force the idle higher at the carb by turning the primary throttle screw it means I don't need to use the choke in this situation, but when I go on a journey where I do reach decent temps, the idle is of course racing when I get into town again- this is worse in my opinion because the gears suffer, and I'm not playing that game- Bis boxes are worth as much as my car.

I have a bad combo of over-cooling and poor tune.  I need a good session fiddling with timing and mixture and then perhaps the worst of these symptoms will go.  The over-cooling is obviously at it's worst at the moment because of the weather- I don't recall mucking about like this when I got it in the summer.

[Lewey]

May have gone a long way to fixng both my woes.  After fiddling with timing by ear and trial and error driving, I managed to get the timing spot on for MY car at least and it goes and starts well now.
Timing strobe 0, Ears 1.

Also, have put a touch hotter plugs in and that seems to be boosting temperatures enough that I can use the choke sensibly now. Nice.

[Chris Lakin]

well done m8!!

i have been meaning to ask the following question for months, when you cut/turn ignition off, does your BIS still continue to run for a second or two?

mine does, but i dont know if this is a characteristic or carbon build up?

what do you think? do you guys get it on both the BIS and aircooled?

regards

Chris

[Chris Lakin]

my BIs starts ok when cold after a few attempts, with choke on and apply a bit of gas to stop it cutting out, then after a minute it progressively gets weaker and starts sounding like its chugging, which gets slower and slower until eventualy it cuts out,

its ok when the car has warmed up a bit.

anybody have any ideas why this could be?

regards

Chris

[126cab]

Hi Chris, if it is running on after switching off this is called pre - ignition, usually because the timing is too far advanced or in extreme cases hot carbon dropping into cylinders causing pre ignition (ie) running on, try retarding the timing a little and you might you cure it and it may fix the difficult starting prob as well, you need a retarded spark for good on the button starting,  dont over do it mind.