Timing for ZC DOHC

[Dubs13]

What is the ideal reading for a ZC DOHC when testing the timing on a timing light? I heard it's from 10-14, is that true?

[95 ZC LX]

the red mark at idle...i think its 16 degrees but not 100% sure.
white mark is TDC (when #1 is on compression stroke at TDC) and the red mark is the base ignition timing...

[Dubs13]

the red mark at idle...i think its 16 degrees but not 100% sure.
white mark is TDC (when #1 is on compression stroke at TDC) and the red mark is the base ignition timing...

Really? Cause for a D16a1 it's supposedly 10-14, y would the ZC be so much higher?

[95 ZC LX]

well, like i said, not 100% sure....i would just set it to the red mark, then if you have an adjustable timing light, adjust the timing light to the white mark and see what is on your display..thats what your timing is at...

[Dubs13]

I still need a sure answer from someone. I read somewhere it was 18 btdc but that seems a bit high so I don't wanna risk putting it that high. I'm at 12 right now and I find it to be way too low, my car is barely pulling even with 91 octane gas. Can someone answer my question please asap? Thanks.

[95 ZC LX]

you can run as much timing as you want, as long as it doesnt ping...

[Dubs13]

you can run as much timing as you want, as long as it doesnt ping...

What are you running?

[jlicrx]

What is the ideal reading for a ZC DOHC when testing the timing on a timing light? I heard it's from 10-14, is that true?
ignition timing for DOHC ZC:

16 degrees plus or minus 2 degress Before Top Dead Center at 800 rpm plus or minus 50 rpm in neutral

[Dubs13]

ignition timing for DOHC ZC:

16 degrees plus or minus 2 degress Before Top Dead Center at 800 rpm plus or minus 50 rpm in neutral

FINALLY! lol, I was waiting for this. That means by timing is way too retarded, it's at 12 right now, lol.

[Dubs13]

One more question about ignition timing. When you guys say 16 degrees +- 2, do you mean with jumping the ECU or without? Cause with jumping I'm at 18 btdc and without and I'm at 15 btdc. Supposedly you're always supposed to jump it before you do the timing so I just wanna make sure you guys took that into consideration when you gave me the timing specs. Thanks.

[jlicrx]

One more question about ignition timing. When you guys say 16 degrees +- 2, do you mean with jumping the ECU or without? Cause with jumping I'm at 18 btdc and without and I'm at 15 btdc. Supposedly you're always supposed to jump it before you do the timing so I just wanna make sure you guys took that into consideration when you gave me the timing specs. Thanks.with connector jumped - 18 with it jumped will be fine

[Dubs13]

with connector jumped - 18 with it jumped will be fine

My mechanic checked it for pinging and it was not even close to pinging, it's actually running pretty well. It probably helps that I run 91 octane though. If I accidentally run 87 one day, is there a risk that I might start pinging at that setting? And, should I advance it even more from there or is 18 enough?

[jlicrx]

My mechanic checked it for pinging and it was not even close to pinging, it's actually running pretty well. It probably helps that I run 91 octane though. If I accidentally run 87 one day, is there a risk that I might start pinging at that setting? And, should I advance it even more from there or is 18 enough? at 18 it will still be o.k. with 87 octane - no need to go beyond 18 with stock engine

[Dubs13]

at 18 it will still be o.k. with 87 octane - no need to go beyond 18 with stock engine

Done and done. Thanks for all the help man.

[rick gnodde]

ok just to be clear:

i live in holland the basic fuel is 95 octane but i always use 98/100 octane fuel

so how much can i advance my timing ?

dohc d16z5

[jlicrx]

ok just to be clear:

i live in holland the basic fuel is 95 octane but i always use 98/100 octane fuel

so how much can i advance my timing ?

dohc d16z5octane rating is not the same worldwide - your octane is not the same as ours - here is a little info on it:

Octane is measured relative to a mixture of iso-octane (2,2,4-trimethylpentane, an isomer of octane) and n-heptane. An 87-octane gasoline, for example, has the same octane rating as a mixture of 87 vol-% isooctane and 13 vol-% n-heptane. This does not mean, however, that the gasoline actually should contain these chemicals in these proportions. It simply means that it has the same autoignition resistance as the described mixture.

A high tendency to autoignite, or low octane rating, is undesirable in a gasoline engine but desirable in a diesel engine. The standard for the combustion quality of diesel fuel is the cetane number. A diesel fuel with a high cetane number has a high tendency to autoignite, as is preferred.


Measurement methods
The most common type of octane rating worldwide is the Research Octane Number (RON). RON is determined by running the fuel through a specific test engine with a variable compression ratio under controlled conditions, and comparing these results with those for mixtures of isooctane and n-heptane.

There is another type of octane rating, called Motor Octane Number (MON) or the aviation lean octane rating, which is a better measure of how the fuel behaves when under load. MON testing uses a similar test engine to that used in RON testing, but with a preheated fuel mixture, a higher engine speed, and variable ignition timing to further stress the fuel's knock resistance. Depending on the composition of the fuel, the MON of a modern gasoline will be about 8 to 10 points lower than the RON. Normally fuel specifications require both a minimum RON and a minimum MON.

In most countries (including all of Europe and Australia) the "headline" octane that would be shown on the pump is the RON, but in the United States, Canada and some other countries the headline number is the average of the RON and the MON, sometimes called the Anti-Knock Index (AKI), Road Octane Number (RdON), Pump Octane Number (PON), or (R+M)/2. Because of the 8 to 10 point difference noted above, this means that the octane in the United States will be about 4 to 5 points lower than the same fuel elsewhere: 87 octane fuel, the "regular" gasoline in the US and Canada, would be 91-92 in Europe. However most European pumps deliver 95 (RON) as "regular", equivalent to 90-91 US (R+M)/2, and even deliver 98 (RON) or 100 (RON).

The octane rating may also be a "trade name", with the actual figure being higher than the nominal rating.

It is possible for a fuel to have a RON greater than 100, because isooctane is not the most knock-resistant substance available. Racing fuels, straight ethanol, AvGas and liquified petroleum gas (LPG) typically have octane ratings of 110 or significantly higher - ethanol's RON is 129 (MON 102, AKI 116). Typical "octane booster" additives include tetra-ethyl lead and toluene. Tetra-ethyl lead is easily decomposed to its component radicals, which react with the radicals from the fuel and oxygen that would start the combustion, thereby delaying ignition. This is why leaded gasoline has a higher octane rating than unleaded.

to answer your question, you should be able to get by with ignition timing at 20 degrees - remember, the timing we are talking about is static ignition timing at idle - the ECU will advance the timing as engine speed increases as controlled by the ECU - as engine speed increases, you can have (and need) more advance due to the time delay between when the ignition fires and the actual combustion of the fuel mixture

as a side note: here in Colorado where i am at elevation of 6500ft we have regular at 85 octane, mid grade at 87 and premium at 89-91 - this is because we don't have as much air, so we are starting out with basically a rich condition which has less chance of detonation (also creates less power)

[rick gnodde]

thanks for youre reply
i will keep it in mind

where i live the ground is 7 - 11 meters below sealevel

1 meter = 3 feet ??

when the chip is ready i let u guys know the results

[rick gnodde]

ok yesterday i turned the distributor towards the intake manifold

about 1,5mm (i do not have a timinglight but i am going to buy one)

the engine runs more smooth and mayby a little bit faster but thats hard to tell

thanks

[Dubs13]

ok yesterday i turned the distributor towards the intake manifold

about 1,5mm (i do not have a timinglight but i am going to buy one)

the engine runs more smooth and mayby a little bit faster but thats hard to tell

thanks

As far as I know advancing your timing is all good as long as you make sure you're not pinging, that's the key.

[rick gnodde]

the problem is that u don't always hear or feel the pinging