Timing For E5 And E10 Petrol DJ2.1 Engine Query

[maxstu]

I realise this subject has previously had it fair share of postings. But once more l seek re-assurance from the folk of this fine club. Aren't we lucky.

Coming up to 1500 miles since full engine rebuild, and using E5 97 octane fuel with timing set at 10° BTDC at present.

Yet as the price of fuel continues to increase once more, l'm considering retiming to 5° and going back to E10 95 octane (prior to rebuild I ran my DJ on this grade of fuel for six years and no issues. Fuel lines all changed in 2020 and ethanol safe).

And, after listening to a BBC Radio 4 SLICED BREAD on petrol......

https://www.bbc.co.uk/programmes/m001hfqq

...it made me ponder how just two octane knock ratings of between 95 and 97 could possibly damage my engine if l didn't adjust timing accordingly; I bring this up, because, with the fuel gauge needle the wrong side of the left red block, l recently stopped for fuel and the station only stocked E10. So l put in 20 quid and carried on until l found E5 about 20 miles away. Then filled up.

Can it really cause that much of an issue of just two knock ratings? And to my mind's eye, l've not experienced any thrilling new ponies emerging from the engine running E5 against E10. But that could be down to my relaxed and cautious driving style rarely above 60mph and enjoying the scenery. The autobox enhances sedate driving, too, in my opinion.

Is there any benefit from filling with E5 at 10° when towing our caravan, for instance? Are we being conned in to buying petrol for unnecessary scaremongering reasons. It's about 50p per gallon more expensive to use E5? It all adds up on a long tour.

Your views please?

Regards
Stuart

[cobblers]

I have swapped between both types and adjusted timing to suit. Noticed precious little difference, in fact I think I prefer the timing set for 95 octane as the engine seems to be less laboured at low RPM and I don't notice any power difference up top.

With it set for 97 octane, if I put 95 in I have once or twice heard pinking, but truth be told it's a doka with mud tyres on so it might be pinking it's head off and I just can't hear it - However I'm not sure if my DJ has DJ or MV pistons in it so the compression could be too low to take advantage of the better fuel.

My MPG is absolutely dire on either fuel (12-18mpg), and my driving is too varied to really compare the two fuels.
The only reason I'd buy E5 is if my fuel pipes were ancient or I used the van very infrequently and didn't expect to have used the tank up within a month - e10 is more likely to absorb water.

[maxstu]

Is it as simple as setting timing to 7.5° or 8° to allow for either? That is far too an easy answer

When setting my engine's timing the mark moves around either side by a couple of degrees. So almost impossible to get an accurate 10° timing, anyhow.

[Aidan]

I'm running 10' and use E5 most of the time, don't find any real difference in drivability using E10 but mpg is lots better on E5 (as is top end performance) so makes up for cost of fuel difference. With my set up I'm getting average 24mpg on a Syncro caravelle with 5.43 final drive, 0.82 fourth gear and 205R14C tyres. I drive the engine hard but the vehicle easy, lot of (slightly taller) 3rd gear at around 40mph on rural roads, and keep it around 55-60 on the long run main roads, not interested in driving faster. Traffic is light enough here in Wales, so I pull in and let the faster traffic by if they are building up behind me rather than have them tailgating and getting frustrated or speeding up to kep them happy. Everyone in such a rush to get nowhere and do nothing these days.
If I wanted cheaper fuel costs I'd run a smaller newer vehicle, not worry about a few 10p per litre price difference

[cobblers]

Yeah, there's a fair amount of lash in the distributor drive etc. Did you have the idle speed stabiliser linked out etc?
Mine is set for lower octane fuel, but I've been fairly generous with it and erred on the advanced side. Like you say, probably near 6/7 degrees.

[Mocki]

As I’m running a carb,( its not just the fuel lines it eats, its the seals and diaphragms ) i stick to the e5 as much as possible , but lets remember , its described as “up to 10%” and “up to 5%” so actually it may well be less , probably is …. However , the mpg is definitely better on e5 , and as Aidan says , makes a lot of the price gap back . One thing i am not going to do is leave it standing when not in use with e10 in the tank , the more it has the chance to suck in moisture the more issues will show down the lines in my thinking , so i make sure its brimmed with e5 when i know I’m going to have it not in use for more than week .

I’m working on the theory the less of e10 i can use the better , if i have to mix it , i try to make sure its well diluted with the good stuff , I’m not planning on changing my timing ,, and mine is also a auto 2.1

[silverbullet]

fwiw there is long-life zero ethanol fuel available from Aspen for garden machinery, available in 4-stroke (and 2-stroke 50:1 premix) which could also be used as a long-term storage or a flush-through option if you rig up a small temporary fuel tank. I first used it after refurbishing my chainsaw.
It is claimed to be stable for years, but at a price...my local supplier has it at £24 for 5 litres and thats cheaper than tinterweb prices by a big margin.
https://aspenfuel.co.uk/

[maxstu]

Yeah, there's a fair amount of lash in the distributor drive etc. Did you have the idle speed stabiliser linked out etc?
Mine is set for lower octane fuel, but I've been fairly generous with it and erred on the advanced side. Like you say, probably near 6/7 degrees.

Not had an idle speed stabiliser in the engine bay for years. When l got the camper it was stalling in the most inappropriate places. Roundabouts and junctions etc.

Took the camper to an old skool VW trained engineer. Explained the problem. He promptly pulled out the two leads and joined them together. Then ripped out the ISS and binned it. Not a cut out problem since.

[maxstu]

I'm running 10' and use E5 most of the time, don't find any real difference in drivability using E10 but mpg is lots better on E5 (as is top end performance) so makes up for cost.
If I wanted cheaper fuel costs I'd run a smaller newer vehicle, not worry about a few 10p per litre price difference

I understand your logic. And when employed it wasn't an issue; in our first T3 pop top camper ( 2007 to 2016) we covered 70k. Not a care in the world.

Yet, after retiring far too early, and with the cost of living spiralling, we keep to a fairly tight budget nowadays. So why give the tax man extra income via E5 pump prices when E10 is perfectly capable of doing the job?

[Stesaw]

With my Carb DJ I've got it timed to the timing mark, so 10 degrees.. I think, do some tripple pulleys have 5 degrees and other 10?.. either way on the timing mark. I mix and match fuel and don't bother changing the timing as I use my van daily its not sitting around so I'm not worried about the E10 going bad.

I've had our brick up to about 75 mph on the motorway about 4.2k revs and it still wanted to accelerate.. but it gets pretty sketch at that speed in a box so I went back to about 60 after I overtook. I've sat comfortably at 70 on the motorway but having the AAP box helps that no end.. if I tried that with the diesel box this van came with it would have been screaming.
I've got to investigate some kangarooing when I'm off throttle.. I think either my chokes being daft or it's overfueling a bit, electric facet pump 3 bar.. shouldn't think that would cause any carb issues without a pressure reg.. but its something to investigate.

[Aidan]

Mine is running with a working DLS and the idle control system functioning correctly, when I bought it the DLS was missing, the air bypass valve was sticking, the idle switch wasn't set right and the idle screw was opened up and the co2 screw maxed on bypass, just so it would start when cold, but then it idled at 1400rpm when hot, very typical of older DJ badly maintained. It needed a new accelerator cable, new plugs, replaced the leads and coil, Dls and air bypass valve (used genuine), new cap, rotor arm and air filter just to get it back to happy then set it up properly, now it runs very well, burning a little oil (113k miles original I reckon) and weeps a little water somewhere haven't found the leak yet but no oil in water or water in oil. I will do a compression test soon, but it starts first time, revs happily over 4000, lots of power and torque at 3000, idles at 850rpm smoothly hot or cold, the idle screw is fully in, the co2 screw set right, hydrocarbons a bit on high side but pass mot and within original spec, but those who have followed me do report a bit of blue in the exhaust and it is using 500ml oil /1000km so poor previous maintenance is evident in wear. Almost ready for another oil and filter change, oil is starting to discolour and it's done nearly 4k miles since I got it sorted 4 months. 10w/40 Quantum Synta semi Synthetic.
I haven't touched the injectors yet, will get them tested and ultrasonically cleaned. No flat spots or hesitation I can notice, the AFM seems good. No vanagon harness fitted or mods that I know of.

If changing fuel makes no difference to you on mpg then run the cheap stuff, but the difference offsets the price for me, noticeably less bang per buck on E10, and I haven't done the fuel lines yet so I try to stick with E5 as much as possible. Haven't noticed any pinking on E10. I don't do short journeys, 10 miles each way minimum, occasionally, all the rest is long runs, I cycle locally as that is best for me and everyone else.

[maxstu]

With my Carb DJ I've got it timed to the timing mark, so 10 degrees.. I think, do some tripple pulleys have 5 degrees and other 10?..

Could be a MV/SS PAS pulley if showing timing mark at 5°.

[Stesaw]

Perhaps.. If I remember go westy have a timing marker you can print out so maybe I'll do that and check if its 5 or 10 degrees on the pulley.

[maxstu]

Perhaps.. If I remember go westy have a timing marker you can print out so maybe I'll do that and check if its 5 or 10 degrees on the pulley.

Digifant timing same as digijet?


https://gowesty.com/blogs/article-libra ... efi-timing

[Stesaw]

the only clearly visible mark on the pulley is a 5 degree BTDC mark.

Well.. if thats the case I'm at 5 degrees.. I think I'll do the 3k 35 and see how that goes!