TeamSwift

Wondering how often to check the timing, if you NEVER have fiddled with the engine.

Even necessary?

A timing light is only USD 35 so it's not going to break the piggy-bank, and I have 3 cars to check the timing on, Swifts and Beetle car. Beetle car might be difficult as there is no RPM meter!

It's good to know what your timing is set at, you never know if it's been messed with. Once you have set it there's no need to check it after that unless you are working on your engine. Not sure what car you have but the stock timing for the gti is 8 degrees advance, you can advance it to 12 degreesfor a noticeable increase in get up and go, and better mileage,

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89 Swift gti
Modified B16 P29 75mm pistons,13:1CR, cultus intake, genie header, genie exhaust, 3tech head, 3tech 222/365 cams, 3tech UD pulley, megasquirt 2.0, 60mm throttle body, Aluminum flywheel

Interesting, engine is 1300 G13A carburetor.

So you are saying the correct is 12 degrees for better performance and mileage, but why was it initially 8?

Using 95 octane unleaded fuel, think I filled up one with 98, engine seems to kick more off. Or something I imagined?

"Correct" timing advance is an elusive term, the optimum setting varies from one instant to the next, that's why almost all cars today have knock sensors which allow the computer to adjust it constantly. "High Test" gasoline doesn't burn as easily and actually has a little bit less energy in it, but it allows for more timing advance which better uses the energy that is there. More advance provides more power and better mileage, but at a certain point the mixture starts to light off on it's own, and that can cause engine damage if allowed to continue.

When you advance the ignition timing, at a certain point you'll start to hear a slight rattling noise which sounds as if there are marbles or ball bearings inside the engine. It usually occurs first at 1/2 to 2/3 throttle when accelerating or going up a slight hill. This is called ping and is the first sign that you've got too much advance. It can progress on to knock which is a deeper, harder banging noise that will cause damage. The perfect ignition advance setting is as much advance as possible, with a faint hint of ping on occasion.

The problem here is that on a simpler computer control system such as we have, it's a mechanical adjustment, and the perfect place for it to be varies from instant to instant. The onset of ping is affected by temperature, altitude, humidity, the condition of your engine, your driving style, geography of where you are driving, and the quality of the fuel in your tank that particular fill up. Because there are so many variables, the manufacturer errs on the side of caution and leaves the timing 5° or so behind what is theoretically possible, as a safety margin.

If you know what ping sounds like you can exploit some of this safety margin and get some free power and mileage. If you don't know what you're listening for don't F with it, you could damage the engine. Most Suzuki G engines have a recommended setting of 5° advance and it's pretty much in the center of the slot in the distributor housing. Most will take 8 - 10° without any problems, and it will look roughly like the picture below. Some will take as much as 12 -14° of advance, but that's usually because they have low compression already from being worn.



IF YOU DON'T KNOW WHAT YOU'RE LISTENING FOR, STICK WITH THE FACTORY SETTING

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91 Pontiac Firefly Turbo
10 Suzuki Kizashi


Alcohol, Tobacco, and Firearms
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Thank you for that excellent explanation!

A possible solution not to do any harm is to meet you half way between factory timing and max suggested. Would probably do no harm as engine is a bit worn. One more HP would not be wasted!

A bit on the side the first cars I drove, A Mazda and a Suzuki used a single barrel carburetor, so I had to listen to the engine carefully when pressing the gas pedal to avoid any "knocking sound".

As I am running a double barrel carburetor now, never heard and "rattling" and it sounds smooth.

"The perfect ignition advance setting is as much advance as possible, with a faint hint of ping on occasion."

Usually, yes.

I use an emulator to play with fuel and timing maps on a Cultus ECU that can switch maps based on a signal from the knock sensor. I'm using this setup to run a g13b engine with stock internals (no JDN Cultus pistons), however. The JDM setup is indeed knock limited or presumably there would be no need for a knock sensor.

But...

While I've had to rely on others to do dyno testing for me, on US market 93 octane pump gas and stock compression, the g13b engine with non-Cultus internals is not knock limited, i.e. you can advance ignition beyond the value that gives maximum torque without experiencing significant ping, so no need to advance until you hear it. Another reason our engines did not come with the knock sensors too, I suppose.

That may not be true with lower octane ratings, and may also be dependent on the map.

It's also still a good post, but I thought I'd chime in for the benefit of experienced tuners and let others know that, in my experience, if you want to make the most power on an export-market g13b, you'll need a dyno to optimize timing or use a map that is known to work for stock internals. That's not to say you can't just twist the distributor a bit for more power, in fact, there's a pretty healthy margin of error, so go for it. Only a dyno can tell you when you've got it dialed-in, however. That's more or less true anyway, but you can get really close to the most effective timing on many engines by tuning for the edge of ping. Not so here, as far as I can tell.

Anybody disagree? I'd love to hear another perspective, as though I've worked with others that have spent time on a dyno that supports what I'm saying, the dyno time to absolutely confirm this on my own is too expensive for me.

Yet another reason to build it with high comp pistons

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Spanish Inquisition Racing chip burning service--build yourself a custom chip!
http://www.teamswift.net/viewtopic.php?f=17&t=57216

I spend most of my time over ar GeoMetroForm, and must admit, I was thinking of the G10 when I wrote this.The specific numbers, and the picture are for a G10, but the concept is sound.


That's universal

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91 Pontiac Firefly Turbo
10 Suzuki Kizashi


Alcohol, Tobacco, and Firearms
Should be the name of a convenience store, not a government agency