Dummies guide to Changing Timing

[madkeen]

Hi folks. Can someone please kindly enlighten me as to what exactly 'changing timing' is, how it happens, why people seem to do it on mx5's a lot, and what gains it can make on an NA8?

Thanks for not laughing.

[hks_kansei]

There's different timing, cam timing, ignition timing.

The commonly referred to one is Ignition timing.

Ignition timing denotes when the spark fires to ignite the fuel/air mix int he engine, it is measured in degrees before ot after Top dead centre (when the piston is at the very top)

Advancing the timing means the spark fires earlier, or more degrees before TDC.


There's a lot of science around it, so if you want to know the specifics i'd check google etc.

If you just want to know how to change it, i'll post below

[hks_kansei]

To change the timing you will need:

Spanner (cant remember size, probable 10 or 12mm)
Timing light
Chalk pen (or paint marker/whitout)

Open the bonnet and find the front pulley at the bottom.
around the edge of this will be a tiny notch, this is your timing mark, paint it white to make it easier to see.
you will also find mounted to the engine, near the pulley edge, a timing mark on the engine, it will be a small scale like this:



once those are both marked you can then hook up the timing light.
Clamp the induction clamp over the plug lead for cylinder 1 or 4 (front most, or rearmost)
Clamp the black clip to the engine block, away from spinny bits.
Clamp the red lead to a 12v power source. NAs have a blue plug on the righthand side of the bonnet for this, remove the blue blanking plate at clip the lead to that.

now start the engine.

When you pull the trigger on the timing light the light should strobe. if not, check it's hooked up right.

Shine the strobe at the timing marks you looked at earlier, you should see the mark line up on the scale, if factory it should be at I think the 10 mark. (being 10dbtdc)

To adjust the timing you find teh CAS on the back of the rocker cover

"crank angle sensor" in the pic (it's actually a CAM angle sensor, but meh)

Loosen the bolt on it, and you should be able to rotate the CAS each way, as you do the engine sound will change.
turn it while shining the timing light at the marks until you are at teh timing you want, from memory 14deg is waht people tend to use for modern fuels.

tighten the CAS bolt, remove the timing light, and enjoy.




edit:
I havent done this in years, since I have an NB none of it applies, so I may have forgotten a step (maybe the GND-TEN short?)
ALso note I think the CAS on the NA8 is on the opposite side to the NA6.

[madkeen]

Thanks HKS_Kansai! Great post.

Any opinions on whether this is worth doing on an NA8 would be appreciated. Are there any risks? (assuming it's done right.)

[speed]

Nice post HKS!
The only info I have to add is, it's a 12mm spanner and yes, put a paper clip between GND and TEN before connecting the timing light.

You will find the car is a bit zippier after advancing to 14 degrees.

After unplugging the timing light you may need to adjust the idle screw but each to their own.


Sent from my iPhone using Tapatalk

[Mr Morlock]

A very old concept not understood by many of the younger generations is the book. There are any number of books about cars / engines etc sitting on shelves at libraries or at old blokes homes waiting to be read. A forum is just a a veneer of paint. What I can tell you is that in the old days before car engines got computers and electronics the bane of peoples lives was adjusting timing and hoping it was right for a week or a month or whatever. Reaching over the distrbutor or disturber as we called them and loosening the lock bolt was often done just to turn it this way or that to get the wretched engine not to ping ( pink) or to perform a bit better. And then along came electronic ignitions and they ran so much better and no need for fiddling. Best advice about timing is leave it alone if a car is running well- most of us run for 10- years with this car or that and never touch the timing.

I do hasten to assure the OP that there is absolutely nothing wrong with the question. Still whenever a question is asked and a reply is given about automotive terms it begets another question like what is TDC what is valve overlap, what is piston slap and on it goes. Getting a bit of knowledge actually takes time and reading and talking to guys does put some flesh on the bones. Personally I struggle with topping up Myki on the rail system and I completely failed at how to use the self serve copying machine at Office Works but fortunately like the OP I asked the nice lady to help out a a silly old git i.e. me. PS never touched the timing on my NB and it runs a treat

[madkeen]

Thanks Mr.morlock. I appreciate the feedback. I'm now in 2 minds as to whether to tweak the timing or not. My car is heading into Automotive Plus next week so I might ask the question.
Meanwhile you may be pleased to hear I actually have a 'book' on order from eBay :0

[SuperMazdaKart]

I did it on my NA6 when I had one. Made the existing torque band more usable. Torque comes in at a lower RPM then before. But you may also need to change to a 95 octane unleaded petrol as well, if not 98 octane.

[93_Clubman]

Anecdotally NA6 seems to benefit more from this than the NA8, but there's a slight benefit with the NA8.