Ignition timing

[Purfler]

'93 NA LE

Two weeks ago I replaced the o-ring on the crank angle sensor (still have the scars - you cannot get the $#$%! thing out, it had to be done sort of in situ). I had marked the position of the CAS, but didn't check the ignition timing after I did it. This bugged me and last Sunday I got out the timing light and checked the timing. It was in advance of the factory recommended 10 degrees BTDC, but I didn't pay any particular attention to where it was. Set it to 10. Then I drove it - what happened to the low rev torque? (this is relative, we're talking a small 4 here). Thought I'd stuffed something up (again!). Thought about it and realised I hadn't (I have done ignition timing a few times over the last 35 years). Googled mx5 ignition timing and found this really good site:

http://www.miata.net/garage/KnowYourCar/index.html

which you all probably know about already. As most of my driving is done in peak hour traffic (sigh) low end torque desirable. My question, does anyone have particular experience with advancing the timing to 14 degress BTDC. What plugs/fuel do you use if you do?

Regards,

Tim

[Locutus]

general consensus is 14deg is best for NA6, and 12deg for NA8.
standard plugs are fine, but 95RON minimum after the timing bump. i needed 98RON in summer.

note that every motor is different. some NA6s can run 16deg+ without any issues, others don't like anything beyond 12-13deg. don't be afraid to muck around with it to find your sweet spot.
although you get a boost in torque, the motor will be more harsh in stop/start traffic and in carparks the further you advance the timing.

[Wuey]

My previous NA6 would ping in summer while timed at 14deg unless I used premium fuel. Otherwise it was fine in the cooler months. Eventually I settled for 12deg and ran on standard fuel. Do turn down your sound system and keep an ear out for pinging after you've done the timing to avoid burning holes into your pistons.

Trust me, you CAN remove the CAS although it's a lot of fiddling. I shot a video after telling a couple of club members how to do it. They were skeptical at first but it did come out.

[Purfler]

Trust me, you CAN remove the CAS although it's a lot of fiddling. I shot a video after telling a couple of club members how to do it. They were skeptical at first but it did come out.

I can fit a sound post in a violin (it fits inside slightly behind the bridge between the front and the back, it must be precisely placed, be the correct height and each surface has to mate perfectly and the surfaces slope in two directions. None of this can you see from outside) but buggered if I can see how you can get the CAS out without removing a number of other things first. Believe me, I tried. I did find taking the cover off made fitting it back easier, until I had to refit the cover screws.

Changing the cam belt on my old ST162 Celica was always much easier if I removed some of the engine mounts and lowered the engine a bit. I was half wondering if I would have to do soemthing similar until I decided I didn't actually have to have the CAS in my hand.

Regards,

Tim

[Wuey]

When I watched three guys tried to figure out how to remove the CAS from an early NA, I just smiled and urged them on. "C'mon let me assure you it can be done, you just have to find a very precise orientation." A couple of minutes passed, and just when the guy with the CAS in his hand about to utter a few French words, the CAS magically came out!

Your car could have been built differently but who knows.