easy timing adjustment for that new engine

[gem on dubs]

ok. that spankin new 10,000 KW engine is in. HAHAHAHA, so you wanna set the timing so you can head out to cruise. turn the car over, and start driving.get her up to operating temperature. now drive at a normal pace. FLOOR IT!!!, no knocking??? advance it a few degrees. keep repeating this until you get it to start knocking. then retard it 1-2 degrees, and this is a pretty much perfect timing setting for your new engine!!! happy dragging!!!

[RiCE BOi]

An extra peice of advice if you embark on your way to find the best timing for your engine, use the road test as 'Gem On Dubs' has provided but...
Before you go out, put a 98ron fuel (ie; BP Ultimate, Mobil Synergy, Shell Optimax) in your tank. Best results are found if you run your existing petty very low, then put around a half or so tank in (20 odd litres is sufficient).
Also, for a true test of detonation find a reasonable hill or incline. Approach it at an average speed (say 60kph), then cruise up it applying the accelorator gradually to maintain your speed. The extra labour on your engine will encourage detonation to surface it's ugly head.
This will give you a more safer ignition timing setting. You may find that if you only use flat roads, the timing can be advanced further. But once you hit a hill it may start pinging it's head off, which is what you are trying to overcome.
The only fall-back of using the higher octane fuel to find the optimum setting, is that you should always use that fuel from then on. Some may not want to fork out the extra dollars for the good stuff, but if you do, more timing and horsepower can be found.

[gem on dubs]

now. if you are going to do this, you must always use the correct petrol for your engine!!!

[Gold TX Sleeper]

I've found that with minimal mods on my G200 (cold air, aftermarket filter, Niki secondaries set-up to come on sooner, turbo muffler, 2 inch exh.) and a tank off BP Ultimate, my ignition was best set at 12 degdrees BTDC.
I ran up to 14 BTDC, but it pinged on hills. So after trial and error i found bassically 11-12 degrees to be the optimum.
BTW, a standard G161Z has it's timing set at 6 deg BTDC, i'm not sure what the G200 is set at, so i wont post what my thoughts are.

[rust3]

sounds bodge

[Adam]

You'd *really* better add in something more constructive than the above reply if you'd like to avoid a ban. You could have said "I'm dubious of this method because ______________________" or you could have offered an alternative method.

[Gold TX Sleeper]

I was flicking thru some back issues of magazines that i have stored away (as you do), and came across an old issue of an American 'Tips And Tricks' magazine.
There was an article in there about finding optimum timing for an engine, they knew the age old method of advancing it till it pings then backing it off a few degrees for the best setting. Well, they tested this theory on a dyno and found that BHP readings varied interestingly between the stock setting and the setting of backing it off after it pings. The interesting thing about there findings was that the best setting wasn't found with the traditional method. They found that after a base figure was found, the engine tested picked up approx 4hp with the traditional method of timing advance - which was 15deg adv. Gained 3hp with 12deg, 6hp with 10deg, and it started to teeter off with any more retarding.
So i thought i'd give it a go on my 2 litre. To my surprise i found the car hooked up and spun the tyres easier with a FINAL SETTING OF 8deg BTDC, Thats a whole 4deg of retarding. Not only do i feel more confident of avoiding detonation, but the car hooks up alot nicer and feels torquier up hills.
So let that be a lesson, try all settings in between max advance to find the one that best suits your engine.

[gem on dubs]

this brought up a bit more info for me!!! so with all this info, remember that if you retad too much, you will gradually start losing compression, not cool if you are naturally aspirated, but sweet as 2 hot bi's wanting three way for the boost boys/girls ( well technically it is cool, because it drops absolute temp below detonation... lets say below 1072 deg)

[Loz]

You dont loose any compression, compression is always constant. When you retard the timing, it spark ignites closer to max compression, and when advanced it ignites earlier in the cycle.

[Ben Wight]

I'm dibious of this method because____:)____ at the point of light detonation, you wont actually be able to hear it, and you will loose some power. You will then jump out, and advance it some more, which will make it detonate worse, possibly so you can hear it, you will then pop the bonnet, and back it off a degree or two, back to where it was lightly detonating, which is not the point of optimum power.

The point of optimum power is at the point just before detonation, whether it be light (barely adiable, particularly with loud exhaust, air filters etc) or heavy (very audiable).

The better method would be adjust the timing to factory specs, and then take it to a dyno, where the trained operator can listen for detonation whilst advancing the timing, with his head under the bonnet!

You have to remember, that the factory timing settings are conservative, but the total timing setting is not, it is pretty much right, unless you use better fuels or change compression ratios, etc.

The standard timing settings can be advanced a fair bit at low revs, but changing the static timing will also make the total timing increase by the same amount, which will probably make it detonate, and because you will be revving at over 3000rpm, you wont be able to hear light detonation.

A 'regraph' is required, not just a blanketing advance of the whole curve.

Ben

[Mooch]

Dyno tune. The only way to really know what's going on. simple. You can get it in the ball park the other way but to really be sure of it you gotta invest a few bucks on a decent dyno tune. Costs stuff all in comparison to a new bottom end.

Mooch

[DrIFtA]

What is the rough going rate for a dyno-tune these days ? I'd assume it's per hour, and would need no more than 2 hours for a complete re-tune to optimal specs for a carbed engine like a Gemini - assuming it's a light tune single carb version. eg; weber, extractors/exhaust/mufflers, cam, filters, cold air - the usual.
So what have you guys paid, where from, what did you get for your money, how long did it take, and does a KW/BHP readout cost extra ???

Danka.

[Poida]

Well spoken Ben.

As you say the detonation you don't hear is a problem people overlook. Only an experienced tuner will be able to detect this condition. There is more to tuning the ignition timing than simply eliminating a noticable ping.

Detonation is a guaranteed method of destroying an engine especially if it's being used for performance applications. The long term effects to piston crowns look like ball bearings have been let loose in the engine. Dents across the crown of pistons are the result of detonation.

If you want to tune an engine to get the most power from it, spend a few dollars and get it professionally dyno tuned where it can be tuned under simulated load conditions. When you send it for a tune make sure the fuel tank is at least 50% full.

It will be tuned for a specific grade fuel. What is in the tank is what it is tuned to run on. There is no value in using a particular fuel to tune it then changing fuel after. It can actually cause the one thing you don't want... DETONATION.

Choose your fuel according to the compression ratio of your engine. A bog stock Gemini engine will happily run on unleaded.
_________________
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