Well I finally went and bought a timing light this weekend and set to advancing my timing to 14 degrees. I'm pretty much a mechanical novice but managed to do the job remarkably easily once I'd located everything. The one strange thing I found was the timing markings for my Eunos and I'd appreciate any info from anyone (to confirm I've done things OK!).

There was one white mark on the pulley wheel but no graduated marks above and behind the wheel. Instead there was a piece of black plastic with a white blob on it above and behind the wheel. With the timing light on, this mark lined up with the white blob on the pulley wheel. These marks were to the left (looking at the engine from the front) rather than the right side of the pulley wheel as shown in Rod Graingers book. Anyway, using a timing graduation card that came with the timing light I advanced the timing (pulley mark moving anti-clockwise) my best estimate to 14 degrees. I assumed that the point with the two marks lined up was 10 degrees. Any thoughts / similar experiences?

I've only driven a few miles to work this morning so no real conclusions yet as to the performance gain. (1/00)

The graduated scale is on the timing belt cover. It would be possible to not replace this cover if it's been off (It's made of black plastic). Can you see the bottom part of your timing belt?

If so, you haven't got a cover - hence no graduated scale.

The timing belt is better protected, but it's probably not absolutely essential - plenty of Cossies don't have them, and it does allow you to keep an eye on the condition of the timing belt. But if you feel you ought to have one - visit a scrapyard/ call Jay? (1/00)

Well, the point of advancing timing to 14 deg is to give more top end power, although it does increase power lower down as well. So why do it unless you want more power - and then are you driving 'in the same manner' ?

To get more power, the engine burns a bit more fuel, although it may do so more efficiently.

Overall, I don't think you'll notice any difference - there are lots of other variables affecting fuel consumption. But there again, I don't keep detailed records - just feel pleased if I get 400 Kms from full, and philosophical if I only get 360 km. (1/00)

The benefits are enormous - you will definitely feel the difference once you go to 14. The thing is, all engines are different. Mine has its limit at 14, while other engines are quite happy at even 18. It could be something to do with the quality of petrol here in Ireland - I don't know. Also, the change is completely reversible.

I would recommend the following:
(1) mark the current position of the cam sensor on the cam cover(with a scribe, scratch or pencil mark)
(2) adjust the timing to 14 degrees BTDC as described in http://www.miata.net/garage/ignition.html
(3) make a second mark on the cam-cover

What you have now are marks for 10 degrees and 14 degrees. Try driving with 14 degrees; if you find 'pinging' noises (light metallic tapping) you need to move the cam sensor away from the 14 degree mark towards the 10 degree mark.

My car likes 14 degrees unless the weather is very hot, or if I am driving at > 5,500rpm for long periods. Going to somewhere like 12 degrees is a good compromise, but I can even tell the difference between 12 and 14 just by driving.

As I said before, don't let it put you off: try 14, you'll like it ! I heard a 'rumour' once that claimed the engines were set at 10 degrees at the factory for one main reason: the allegedly iffy quality of Japanese petrol. True ? I don't know ! (2/00)

The timing bump can't be done on an mk2.
1) It's not adjustable
2) It automatically advances the timing as far as it can because it has a knock sensor

So even if you could do it, it would gain you nothing as the ecu would retard it back again. (2/00)

If you are referring to the straight replacement panel type K&N filter I would strongly suggest you get your own and fit it yourself (5-10 minutes, open cover - 4 bolts, remove old, drop-in new, replace cover) otherwise I'm sure the garage will wish
1. to charge a markup on the price of the filter and
2. charge labour for fitting it (probably minimum half hour).

If you do it yourself be sure that the garage are aware that the filter is a "non-consumable" type or otherwise they may just replace it anyway! (2/00)

Well, dunno about poor quality - Octane rating is just that - a rating derived from testing a particular fuel blend in a test engine. In Japan, petrol is 92 or 97 RON - and I believe Roadsters are tuned (ie timed) for 92 RON. And, to set a world-wide standard, the manuals say standard timing is 10 deg BTDC.

If you use higher Octane petrol, you can advance the timing. So, since UK petrol is 95 (Premium) or 97 (Super) RON, we can run 14 deg. If you use 97, you can probably run 18 deg, but there's no advantage except at lower revs, allegedly.

BTW, premium used to be 98 RON - it's been reduced to 97 recently to reduce benzene levels - hazardous, so they've taken some out. And expect it to disappear completely soon. (3/00)

I've been reading up on the adjustment of timing on my car, The manual states the standard timing is between 9 and 11 degrees BTDC.. Two questions.

1. How can 14 degrees be advancing the timing?

2. Everyone seems to recommend this for a performance modification but what does the car actually drive like? ie. more torque? mid range? can anyone who has done this please let me know. (3/00)

14 deg Before top dead centre (BTDC) is before (timewise) 10 deg BTDC. ie the spark happens 4 degrees earlier than it would with timing set at 10deg. So it's 'advanced' (brought forward)

You get a bit more power and torque, especially noticeable at high revs. Just makes the engine feel a bit more lively.

Why is it not set up like this as standard? Due to availability of fuel of high enough octane rating in different markets. 14 deg requires petrol of octane rating 95RON (which we have) . (It will 'pink' at 14 deg with lower octane petrol - not good for the engine)

In other markets this may not be easily available or a cheaper lower octane rating petrol may be available and people may want to run their car on the cheapest petrol they can get. So it's set for the lowest common denominator. We can do better - 14 deg! :-) (3/00)

Octane rating in the US is different. There are two scales for Octane rating, MON and RON. We use RON, they use the average of MON and RON. (They are both derived in the same way, using a standard test engine, but MON has more stringent conditions)

In the ranges used for normal petrol, MON is about 10 points less than RON. (ie 85 MON = 95 RON, 87 MON = 97 RON) So, roughly, US 87 = UK 92 and US 92 = UK 97.

Normal Premium unleaded in UK is 95 (RON) and super unleaded is 97. If you advance to 18 deg and don't use 97, it WILL pink. And that WILL damage your engine. So, if you want to use 18 deg advance, use 97 RON petrol. Most '5s are OK with 14 deg using 95 RON.

IMHO, it is not worth running 18deg due to the cost of 97 petrol and top end performance is not as good as at 14, even if lower down the range 18 deg has advantages. (NB actual timing when the engine is revving are way more advanced than this - these settings are the base settings at idle (850 rpm) which is what you can adjust.) (4/00)

That's *extremely* useful to know! In Garrett's book he just says 'octane' - there is no mention of RON or MON. >

If you advance to 18 deg and don't use 97, it WILL pink. And that WILL damage your engine.

In that case, I'll try 14deg instead (I just went straight to 18 because I thought it suited my driving style better). I agree with you that it's not worth putting super unleaded in an MX-5 just for the sake of running at 18deg. And I certainly don't want my pistons to end up looking like the surface of the moon, even though I have yet to hear any pinking. (4/00)

Now I'm just wondering if I've missed something, or if the US octane rating is different from ours (though I can't imagine how that could be the case)

Yes, it's different. ISTR It's about 5 out. Our 97 is the same as their 92. I guess our numbers are higher so we feel better about paying more for it even though we can't get fuel with as high an Anti-Knock Index as in the US. :-( (4/00)

Sorry, - no.

Centre of the scale is 10 degrees advance (and it's marked). When you turn the camshaft or crankshaft sensor, the timing mark on the crankshaft pulley appears to move against the scale when viewed with a timing light. Each mark represents 2 degrees.

If it moves to the right of the scale, you are retarding the timing - back towards 0 degrees (which is the right hand end of the scale). To advance the timing, the mark must move to the left against the scale - the left hand end represents 16 degrees advance, so you want to be 1 scale division from the left hand end = 14 degrees advance.

There are two marks usually - make sure you use the right one - it might be yellow, but anyway it will be the one close to 10 or 14 when you start (hopefully)

Don't forget - you must have GND and TEN linked, and you should set the idle speed to 850 rpm first (again with GND and TEN linked). Just disconnecting the Idle Speed Control connector and/or throttle sensor doesn't work when setting idle speed - the ECU timing control must be disabled (which linking GND and TEN does) (6/00)

Hope you understood - right and left are difficult terms.

Advance - move the mark to your left as you look at it - anticlockwise

Retard - move to your right - clockwise

I must admit, convention is to use right and left on a car from the point of view of someone sitting in the drivers seat, but that doesn't make much sense when you're stuck with your head in the bonnet sometimes! (6/00)

LOL :o)

Whilst on the point....I have mine set at 15 degrees....is this OK? I once saw a web page with someone's at 16 so thought 15 should be safe?? (6/00)

I tried 10, 12, 14, 16, and 18

14 gave me a definite improvement at low revs and a slight improvement at high revs. 18 gave even more at low revs but impaired top end performance (a bit). It is a matter of choosing between benefits and trade-off. On my car, 14 was the best (win/win) setting. I am convinced that due to manufacturing tolerances, different 5s react differently to the timing mod. I speculate that those who are on the better end of manufacturing tolerances (higher compression) like less/no advance. (6/00)

No, that's retarding.

The scale is kind of backwards, ie it would be marked +16+14+12+10 ----+2+ 0-2 degrees of advance as you look at it. 10 and 0 are marked (10 with the number 10, 0 with a longer division mark) (ignore a sort of T mark above +2 deg), there is a division at minus 2 (ie 2 deg retard) (on mine anyway)

To get 18 deg advance (not particularly recommended) you would need to be off the scale (roughly level with the lh end of the bit the scale is marked on) to your left as you look from the front of the car facing towards the back.

The engine rotates clockwise as you look at it, so the earlier the timing mark on the pulley is illuminated relative to the scale, the more advanced your timing is.

Phew! Is that clear? (6/00)

I had exactly this problem on my 92 1.6 I parked the car and put it in neutral. Then I removed the spark plug nearest the front of the car and put a long plastic rod (beer making spoon shaft!) down onto the top of the piston. I then turned the engine using a ratchet and socket on the crank belt until the spoon was at its highest.

I was then going to make a new mark, but in line with the top-dead-centre mark (T is marked on the scale on the car) I found a small notch in the edge of the timing wheel. I just made this bigger and filled it with paint.

I'm told that the spoon (or anything else that won't scratch the piston) approach isn't accurate enough and that you really need a dial gauge. If you want someone to do the job ask if they have a dial gauge they can use to make a new TDC mark and see if they know what you're on about. (6/00)

There's a yellow dot on the front face of the pulley, but the real timing mark is a groove on the back rim of the pulley.

This will not have eroded etc - you'll find it if you look carefully. I 'paint' mine with typewriter correction fluid - seems to make a much brighter white mark than paint. I keep a bottle in the tool box - useful for marking things which should be reassembled in the same orientation as they started out. (6/00)

You should set the idle without diagnostics shorted out.

1. you have got the idle so far out that it will not adjust without lots of screwing in - screw in until you hit the dead stop
2. you have an air leak into inlet manifold - check hoses like the little blanking nipple at the bulkhead

The idle is set by the amount of air leaking into the inlet manifold;
1/ by leaking past the throttle butterfly
2/ by flow through the manual idle control screw you adjusted
3/ by flow past idle control solenoid (ISC) which ECU uses to fine control speed after you have done the coarse bit on item 2/
4/ air leak into manifold somewhere... (3/01)

It's on the sensor - a sort of circular-ish thing on the back of the cam cover, intake side. (on your car) It's often covered with a strip of tape as a seal, if it's not been touched before. Fairly small bolt 10 or 12mm? I forget.

Loosen it about 1/2 a turn, maybe a bit more, then you should be able to turn the sensor - only a bit! Have it tight enough so that the sensor doesn't turn by itself whilst you're doing the adjustment, but be able to turn it by hand yourself. (3/01)

How do you manually crank the engine to find the timing marks ? (I wanna make them clearer)

Does 'Pink'ing occur at all revs ,or does it vary ?

Can you tell with the car stationary, or does it need to be under load ?

I'm not sure if what I've *occasionally* heard since I've gone 14 degrees is just normal engine noise, or pinking....

Now I've gone back to 13 degrees, I think I'm imagining stuff, but am not sure - loud exhaust doesn't help.....

Any sure fire way to tell if I have a pinking problem ? (9/01)

How do you manually crank the engine to find the timing marks ? (i wanna make them clearer)
Easiest way is to take the plugs out then use a 21mm socket on the crankshaft pulley nut, although in the light of possible sensitivities in that area it might be better to jack up one side at the rear, put it in gear and get a helper to turn a back wheel. Highlight the marks (when you've identified the correct ones!) with typewriter correction stuff.

Does 'Pink'ing occur at all revs ,or does it vary ?
Mainly at low revs under load, but it's possible to get pinking or at least its near-relative, pre-ignition at any speed. But pre-ignition has different causes.

Can you tell with the car stationary, or does it need to be under load ?
See above - you can't tell stationary. Easiest to tell is up a steep hill at 2000rpm or less but open throttle in 2nd or 3rd.

I'm not sure if what I've *occasionally* heard since I've gone 14 degrees is just normal engine noise, or pinking.... Now i've gone back to 13 degrees, I think I'm imagining stuff, but am not sure - loud exhaust doesn't help.....
Sometimes vibration noises can be mistaken for pinking - even by experts! Pinking gets worse if the engine gets very hot.

Any sure fire way to tell if I have a pinking problem ?
If your pistons melt, preceded by a tinkling noise over a longish period when at low revs under load, you have pretty good diagnosis. :-( The other way is to fit a knock sensor (eg J & S - see Moss catalogue) - intended to do auto retard on detection of pinking, mainly if you have forced induction, and monitor its output.

...And how long until my engine melts to highlight that problem!!!???
Some engines can stand a lot of pinking - others can't. My wife's 205 has pinked like crazy since it was new - nearly 70K miles, wih no apparent ill-effects - yet. I haven't actually heard of a 5 melting due to pinking - oh - er - Richard Ducommun melted his pistons once - but not just due to pinking. (9/01)