Advice on adjusting distributor for 95 octane (2.1 DJ)

[Blighty8973]

Hi there,

I'm currently in Ireland, arrived into Dublin on a ferry 2 weeks ago, and have just come out of the isolation and noticed there is nothing above 95 octane in Ireland. This has been the case since 2017 and we have a 2 week tour ahead of us, visiting family

After looking into it the octane enhancers only add between 0.3 and 0.5 octane.

I have already put half a tank of 95 in and driven for an hour and it is already sounding different.

I checked the timing before the trip (98 octane) and it was spot on. It is a 1992 2.1 Digijet (UK model)

I've now forgotten how to do it and I've no timing gun or manuals, so could someone let me know how I adjust my distributor to 5 degrees BTDC (assuming it was already at 10 BTDC), and by eye    please!

Thanks in advance!
 

[937carrera]

"Rough" approach

Dizzy cap off off

Turn to number 1 so that the rotor arm is aligned with the notch in the dizzy.

Look at the crank pulley and see where it is in relation to the TDC mark

You want it to give the spark later/ retard the ignition. Do a bit of maths or measure the pulley and work out how many mmyou need to change the timing by.

Undo the dizzy,make an adjustment, tighten it again and turn the engine over again to confirm the new timing, aligning with the notch each time until you are happy.

This should be useful too

https://club8090.co.uk/forum/viewtopic.php?f=37&t=163388

[Blighty8973]

Thanks, just as a sanity check for me..... (let me know if this isn't right)

Engine is currently set for 10 degrees BTDC (for 98 octane in the UK). 

95 Octane pre-ignites more easily (ie. using it increases the engine's chance of knocking)

So I need to retard the spark more.

Rotor arm goes clockwise, and so I need to turn the distributor clockwise to create a later spark.

Thanks again!

[937carrera]

Thanks, just as a sanity check for me..... (let me know if this isn't right)

Engine is currently set for 10 degrees BTDC (for 98 octane in the UK). 

95 Octane pre-ignites more easily (ie. using it increases the engine's chance of knocking)

So I need to retard the spark.

good so far...and then

You want the spark later, dizzy anti clockwise (opposite to direction of rotation) so it takes a bit more time to get to the point where the spark is provided.... I think

That's why you double check against the pulley

If in doubt about the direction of travel,put the van in top and push it forward.

Make a mark / paint the pulley so you know where you started

[ajsimmo]

You want the spark later, dizzy anti clockwise (opposite to direction of rotation) so it takes a bit more time to get to the point where the spark is provided.... I think

No, other way round. OP was correct, turning it clockwise moves the firing point away so it will happen later.

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[937carrera]

I was thinking of the relation between the rotor arm and the notch instead of the dizzy body movement required to achieve that. That's what comes of mental gymnastics without anything in front of you.

Thanks - hope the rest of the instructions were OK

[ajsimmo]

Interesting that you say the additives only add up to 0.5 RON. Where did this info come from? As I don't really have any experience of using them to comment. It's just that some of the manufacturers' claims are very much more "optimistic"!
NF, for example, claim an extra 6-10 RON points for one product, and a whole +15 for another! This stuff does actually get good reviews from the Irish Subaru Drivers Club.
https://www.nfadditives.co.za/Products_ ... osters.php
I'd be tempted to try it.

E D I T: available in Ireland from here: https://daltons-ie.myshopify.com/produc ... -1l-bottle

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[937carrera]

I tried some of the products more generally available a few years ago (not on WBX, something a bit quicker and fairly quickly went to race fuel). They were potassium based and increased the RON by something like 3 to 5 points.

In very small letters on the back of the bottle it made clear that a point was 0.1 RON. I still have some bottles somewhere. Now either Wynns have reformulated and it really does give 2-5 whole RON increase, or it continues to be misleading. On reading the OP's post I recognised his comment about them not being much good.

To increase RON from 95 to 101 using 1 litre per 60 litres means the additive has an effective RON of 461, which seems way out of any norms. So I went searching and found this https://www.fuelexpert.co.za/Octane-Booster-Shootout.php

Useful because:
1. It confirms the Wynns stuff does talk about a point being 0.1 RON
2. Toluene was tested - it's a common octane booster in race fuels, along with Xylene, helps to get 110+ RON
3. It confirms the NF performance, because
4. They actually tested the fuel after adding the additive..... 2.8 RON in practice

So the magic cocktail has an effective 266 RON

[ajsimmo]

"3. It confirms the NF performance, because
4. They actually tested the fuel after adding the additive..... 2.8 RON in practice"

Ah, so it would do the job then. Good info, ta.

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[Blighty8973]

Thanks, this was where I'd heard that most off the shelf octane boosters only deliver a fraction of a RON
https://club8090.co.uk/forum/viewtopic.php?f=37&t=167408

yep, that fuelexpert.co.za link gives a great write up, 

I'm literally going to carry my timing gun and a bottle of the NF when I'm outside the UK from now on.

I've turned the distributor clockwise as far as it will go without stalling (nearly 1cm). I'm aware that this looses power, and I'm that hoping "over- retarding" it doesn't have any other consequences......... 
 

[937carrera]

That sounds too much, especially when you say "as far as it will go without stalling", so lets do some illustrative maths:

Dizzy diameter is about 9cm so circumference is 28.3cm, easy as Pi

So 1 cm on the circumference of the dizzy cap is 12.7 degrees of camshaft drive

Camshaft rotates at half the speed of the crank, so 1 cm = 25.4 degrees of crankshaft timing, about 5 times greater than target

Retarded timing will loose power and also increase exhaust gas temperatures..... so head and valve temps will be higher and fuel efficiency lower, not a great outcome.

Happy for anyone to cast an eye over the above

Did you mark the original setting ?

[Blighty8973]

Thanks for the figures, very useful, I'll get my calculator and ruler out and will try and see how far I've gone, and what's a better setting. I'll need to do a few thousand miles on it before getting back to the UK.

Yep, and the explosions should be happening at the top of the cylinder rather than (in my case) further down the cylinder lining, so as you say can't be good, thanks
 :ok

[Blighty8973]

yes I marked the original setting, thanks

[ajsimmo]

I agree, waaayyy too retarded now
I'd be putting it back where it was minus a couple of mm, or finding a garage with a timing light, and getting a bottle of that jollop.

[937carrera]

If you are going to be doing a few thousand miles you might want to consider getting another timing light, locally or posted from the UK

There's some on ebay.ie for 40 euros plus post