350i pinking

[richardpowell]

Please can someone help with my recent problem of pinking, some owner before me has disconnected the vaccum system to my distributor, i am guessing to get over the problem of running a low octane fuel(unleaded),I am going to run it on super plus to up the octane up 97 same as old 4 star, but does anyone know what the timing should be when running as standard with vaccum system reconnected.

any help will be apprecated
richard

[Gas Man]

Hi Richard
Many years ago I had a 3.5 Rover (1973) and it was designed to run on 5*.

Try Shell V-Power at this is currently the highest Octane in the UK at 99.
Tesco also do a 99, but my Tiv runs better on VP.

I had to retard the old rover to I think TDC static to stop it pinking like mad. If I remember it was about 4 or 5 degrees more retard than if 5* was avaialble.

Another old method would be to run at 3000 revs and then twist the distributer back and forth to get the best running.


Good luck and I dare say more expert advice will come along.
Steve

[350zwelgje]

Vacuum connection should be connect on std RV8s.
Standard RV8 ignition is 8 degrees before TDC at idle with vacuum disconnected. If the engine is not messed with, and the scale to set it is ok....

It can run easily on 98 unleaded, and with a setting of 5 degrees it should be able to work fine with 95 RON unleaded (haven`t tried this myself) as well.

Other things I would look at:
- The ignition module should be fine
- Coil and all other ignition part to be ok

Rob

[ed_crouch]

2 reasons for pinking:

1: ignition too far advanced. Dont always trust the pulley marks - theyre not always correct!!

2: charge igniting before the plug sparks. could either be too hot a plug, or it could be running lean. This is also called detonation, pre-ignition, detting.

Check you dont have an air leak. If air leaks into the inlet tract other than thru the AFM, then the EFI ecu will not add fuel to match the extra air, and you'll get a lean cut.

Edit to add that my 390SE is about 8* BTDC on 98RON fuel. TO be honest, the Rover engine is fairly relaxed about timing. Its gotta be a long way out for it to complain.



HTH.

Ed.

Edited by ed_crouch on Friday 26th December 20:00

[D1 MAD]

My 350i runs fine on standard 95 ron unleaded, in fact it runs far better on it than 97 ron or the LRP was feeding it for years when it was available, better tick over, more even temperature.

[honestjohntoo]

richardpowell said:

problem of pinking, some owner before me has disconnected the vacuum system to my distributor, i am guessing to get over the problem of running a low octane fuel(unleaded),I am going to run it on super plus ..... same as old 4 star, ..... what the timing should be when running as standard with vacuum system reconnected.

With 3500 cc and nearly 200 horses under the bonnet, save you money run it on regular unleaded, adjust the timing to suit and perform 15 anti power-loss actions, which are nearly all free to extract the maximum performance from your Efi system for the best possible performance/cost ratio.

For a start-off read this to gain an understanding of the fuel quality/ignition timing issue.

http://www.vintagemodelairplane.com/pages/Snippets...

For the record, when built, your engine would probably have been statically timed with vacuum disconnected idling at 600 rpm, at around 6 - 8 degrees BTDC but with todays unleaded 95 RON lose 4 degrees from above, so that will be 2 - 4 degree BTDC.

Now for the lost horses. Just make the best of what you have with very little cash injection. You have already got big bangs inside your 350 but how efficient are they? Getting the very best out of your engine cannot be achieved in one lump, but bit-by-bit, until there are no unnecessary losses.

Assuming that your engine is in good mechanical condition with correct cam/lifter performance and timing, good compression within acceptable limits on all eight cylinders, good exhaust system with no leaks and fresh engine lubrication plus new filter.

These are the 15 things that you can do.

1 Clean all ignition components externally and internally (where possible), spray with moisture inhibitor such as WD40 and wipe dry. If fitted, make sure the distributor vacuum/mechanical advance systems are working smoothly and correctly.

2 Check security and eliminate any corrosion on all ignition LT connections right back to the ignition switch, including local earths.

3 Clean and re-gap the spark plugs - replace if necessary.

4 Check for damaged or out of spec (suppression resistance) HT leads, Clean and replace if necsssary. Change the suppression capacitor connected to Coil +ve.

5 Set up ignition timing to just eliminate pinking with your chosen fuel. (Note: Items 1 thro 5 are to guarantee and maximise the best possible spark at exactly the right time, always.)

6 Ensure that the plenum idle air gallery or idle control system is clear and not contaminated with goo.

7 Likewise the plenum breather gallery, flame trap and LH rocker cover breather filter

8 Ensure the throttle disc(s) is correctly seated at idle (or set to the recommended disc/tunnel gap) to prevent idle speed hang-up and that the whole throttle mechanism is free of unwanted friction right thro from accelerator pedal to throttle pot. (Note - items 6, 7 and 8, Plenum actions are best done on the workbench).

9 If applicable, set the CO content to the recommended range, just erring on the weak side of the mid point and likewise, if possible, reset the idle speed to the recommended level.

10 Set the throttle pot residual voltage to 325 millivolts or what the Efi spec calls for - sometimes 350mv. Make sure the pot is not electrically noisy, causing random overfuelling. When rotated rapidly, check the throttle pot fires the acceleration enrichment and full load enrichment circuits.

11 Verify the fuel pressure operates in the range 26 to 36 psi. not more, not less.

12 Check the integrity of the plenum and all its air/vacuum hoses for rogue air-leaks.

13 Check all Efi loom wiring/connections for faults/corrosion including the crucial Efi engine earths AND the engine earth strap.

14 Check and replace fuel filter if necessary (also make sure the fuel tank is not emitting crud).

15 Because the Plenum really has to be removed for proper cleaning/adjustment, lift and clean the injectors at the same time, replacing the filter baskets and pintle caps (Caps/filters cost only 10 quid per set of ten from Burlen).

None of the above will add anything over and above the engine performance that existed when it was new but you'll be amazed at the horses the above suggestions can release from a tired and maladjusted Injection system.

And the beauty of it is that, apart from time, the majority of these actions are cost free.

To improve performance beyond its original spec there are three more relatively simple things to do.

1 Have the ECU remapped for your needs or fit something from the aftermarket.

2 Fit a rising rate fuel pressure regulator that may give a bit more oomph at the top end.

3 Fit a sports exhaust system that has the effect of improving the overall breathing and minimising exhaust system losses, as opposed to simply adding power which, of course, is not possible.

You may want to consider some reading material on any of the above suggestions, component by component. If so, trawl thro' the stuff available from this index:

http://www.vintagemodelairplane.com/pages/Download...

Most if not all of it will apply to your setup.

Edited by honestjohntoo on Saturday 27th December 21:19

[GreenV8S]

honestjohntoo said:

For the record, when built, your engine would probably have been statically timed with vacuum disconnected idling at 600 rpm, at around 6 - 8 degrees BTDC but with todays unleaded 95 RON lose 4 degrees from above, so that will be 2 - 4 degree BTDC.

I'm curious to know where these figures come from, because they look miles out to me. I expect that would get rid of any pinking problems you might have had, but it's so retarded that you'll be sacrificing a lot of power and running a lot hotter than normal.

[honestjohntoo]

Peter, Surely the acid test is that the fine tuning of ignition timing JUST eliminates pinking as mentioned in the linked essay. Thus the ign timing may be assumed to be exactly right for the fuel/load conditions being experienced during the adjustment process.

Most of my reference data is taken from the Rover SD1 Vitesse workshop manual from which the following is very similar, except my specific data is for "1985 on" and the 35dlm8 dizzy.

SD1 Series 2, Vitesse 1982 on and VDP EFi 1984 on

The engine data is the same except where noted.

Firing order: 1,8,4,3,6,5,7,2 No.1 cylinder front Left.
Left bank odd No's, Right bank even No's.

Approximate engine weight (ready to run) 145 kilos (320 lbs)

Compression Ratio's 9.75:1
Ignition timing (at 600 RPM, vacuum disconnected)
Vitesse 8° B.T.D.C. (before top dead center)
Twin Plenum 6° " " " "
Cylinder pressure 9.1 kgf/cm² (130 lbf/² in)
Oil Pressure @ 2400 RPM 2.5 kgf/cm² (35 lbf/in²)
Idle speed 800 to 850 RPM. CO reading 1.5% ± 0.5%
Twin plenum 825 to 875 "

Distributor
Type Opus Electronic (Lucas 35 DM 8) rotation clockwise.
Pick-up air gap not less than 0.15 mm (0.006 in)
Ignition module Lucas 32 C 12 volt electronic

Spark plugs Unipart GSP 151 Gap 0.90 mm (0.035 in)Twin Plenum " " 4462 " "
Fuel system Lucas 'L' System * Electronically controlled fuel injection

more here

http://www.roversd1.co.uk/tech_data1.htm

[GRIFFONMARK]

That's an interesting point honestjohn, I was always surprised that manufacturers were so slow to develop an anti knock sensor so that engines could run at the cusp of pre-ignition for max efficiency. To fix the timing at manufacture must involve a considerable safety margin reducing efficiency. Maybe what we all need is an after market knock sensor. Anyone know where you can get one?

[honestjohntoo]

GRIFFONMARK said:

could run at the cusp of pre-ignition for max efficiency. To fix the timing at manufacture must involve a considerable safety margin reducing efficiency. Maybe what we all need is an after market knock sensor. Anyone know where you can get one?

Mark - "on the cusp of pre-ignition" I love that phrase, can I have it for my upcoming Rover Efi Ignition Manual please - except I would change it to "on the cusp of pre-detonation" which IIRC is the correct technical assessment of pinking. ie

Pre-ignition - is defined as the ignition of the mixture prior to the spark plug firing. Anytime something causes the mixture in the chamber to ignite prior to the spark plug event it is classified as pre-ignition.

whereas

Detonation occurs after you have initiated the normal combustion with the spark plug - thus - pre detonation is a planned event that happens too early.

There is no attribution but this seems to capture everything.

http://www.misterfixit.com/deton.htm

Regarding knock detection there is a chap called Dave Plowman who frequents one of the Yahoo SD1 forums who is planning to retrofit knock detection to his SD1 so he told me. Hes way outa my class.

Edited by honestjohntoo on Saturday 27th December 23:45

[chedder]

Just a quick question to the O/P how old is the fuel in the tank? Stale fuel can cause pinking issues, or could it be a batch of poor quality fuel that you have purchased?

Just a thought.

Chedder

[GreenV8S]

The ignition timing at wot is the important thing, so depending how much mech advance you have you might need a different static advance. But I'd expect to find somewhere in the region of 8-12 degrees static plus 20 degrees mech advance to give a total advance somewhere between 28-32. Taking 4 degrees out of that is a big change that would cost a lot of power.

I know in theory how a knock detection would be developed, and it would take a lot of work to do it properly for a specific engine. I don't have the resources to do that, and I doubt that any of the aftermarket engine management suppliers would bother. I'm trying to get sensible results from a cheap and cheerful knock detector that seems to be a notch filter plus adjustable threshold, and so far it's not working too well. I can see how useful it would be to use this technique to map the engine to avoid knock, but I'd be extremely cautious about allowing the engine to run up against the knock limit and relying on this system to protect the engine. It would need an extremely sophisticated system to be able to work accurately enough and have good enough fault diagnosis built in to be reliable.

[honestjohntoo]

GreenV8S said:

The ignition timing at wot is the important thing, so depending how much mech advance you have you might need a different static advance. But I'd expect to find somewhere in the region of 8-12 degrees static plus 20 degrees mech advance to give a total advance somewhere between 28-32. Taking 4 degrees out of that is a big change that would cost a lot of power.

Peter, I think you and I either disagree, or, like a failed Channel Tunnel Project we just failed to meet in the middle. Let me clarify the view from this end of the tunnel.

The SD1 book for my engine says 8 Deg BTDC so from empirical experience, using modern low 95 RON unleaded fuel, I retard it by approx 4 deg for the initial static set-up.

I then go out to my favorite hill and give it WOT in various gears to detect any injurious Pre-detonation. If there is some, I retard a weensy bit at a time until it disappears. If there is none, I advance a weensy bit at a time until it appears.

Whichever, I then take off half of the last teensy weensy bit and the system is now set up for my WOT with total disregard for the original static timing, as it was only a stepping stone anyway.

What I can't be messing with is alternative bob weight and springs, which, as long as the residents are in good condition, can do their own thing, as can the vacuum advance when reconnected.

However, strangely or not, whenever I carry out this emrirical process, and then recheck the static timimg, it is always in the range of 2 - 6 deg BTDC (for modern fuels) as opposed to the 8 - 12 degrees which are expected at your end of the tunnel.

Or are there simple explanations for these variances? I'm running a Twin Plenum on 9.75 : 1 CR compared to something different for you, and I'm not too fussed about balls-out performance since I became a brain transplant donor and lost my Boy Racer status last birthday.

Then of course - regarding the inevitable loss of power due to Fuel/Ignition timing compromises - I try to mitigate the effect by applying as many of the fifteen ideas, mentioned earlier, as possible - the end result being that it still seems to be as quick as ever it was.

Edited by honestjohntoo on Sunday 28th December 14:24

[GreenV8S]

honestjohntoo said:

However, strangely or not, whenever I carry out this emrirical process, and then recheck the static timimg, it is always in the range of 2 - 6 deg BTDC (for modern fuels) as opposed to the 8 - 12 degrees which are expected at your end of the tunnel.

The process sounds excellent (allowing some leeway for conditions to change; if you set it up on the edge of pinking in january you might have trouble six months later) but your timing figures do not match what I'd expect. Have you verified that the timing reference marks are accurate? Is the mixture correct under power? It may be that your dizzy has more mech advance than I'm used to and you're ending up with the usual amount of total advance (which is all the matters at the end of the day), do you know what the total advance is? Without vacuum advance I'd expect it to be 30 deg btdc all in plus or minus a couple. If yours is pinking at that there's something unusual going on, perhaps it needs a decoke or the plugs are too hot?

[honestjohntoo]

GreenV8S said:

The process sounds excellent (allowing some leeway for conditions to change; if you set it up on the edge of pinking in january you might have trouble six months later) but your timing figures do not match what I'd expect.

Mothballed in the winter.

Have you verified that the timing reference marks are accurate?

Timing ref marks were OK when I last pulled the rocker covers for a different reason. Always worth checking when the opportunity arises.

Is the mixture correct under power?

Never done Rolling Road or similar, mixture under power highly dependent upon Efi system working as designed (as far as its possible to tell by getting all the components to be in spec) and the plug colour causes no concern after strenuous journeys.

It may be that your dizzy has more mech advance than I'm used to and you're ending up with the usual amount of total advance (which is all that seems to matter at the end of the day).

Just the original 35DLM8 bog standard orig dizzy.

do you know what the total advance is? Without vacuum advance I'd expect it to be 30 deg btdc all in plus or minus a couple. If yours is pinking at that there's something unusual going on,

I cant remember what the full advance was when I last measured it but would expect my non vacuum full advance to be lower than it should be when the engine was first specced and built because I took off approx 4 degrees, so that it stops the full load pinking (which is all the matters at the end of the day) caused by the enforced change in fuel. Pretty much the problem the OP was contemplating in his first post.

perhaps it needs a decoke or the plugs are too hot?

From squinting down the plughole and reading other signs and symptoms, no decoke appears to be needed. Plugs are as specified in the manual.

So at the end of the day, suggestions offered to OP are simply based upon the need to prevent pre-detonation years after the engine was new, in a commercial and green environment where fuel quality is not only imperfect but to overcome the inevitable loss of power thro one action (ign timing), to try and claw it back via attention to some other tuning details.

[shpub]

GreenV8S said:

honestjohntoo said:

For the record, when built, your engine would probably have been statically timed with vacuum disconnected idling at 600 rpm, at around 6 - 8 degrees BTDC but with todays unleaded 95 RON lose 4 degrees from above, so that will be 2 - 4 degree BTDC.

I'm curious to know where these figures come from, because they look miles out to me. I expect that would get rid of any pinking problems you might have had, but it's so retarded that you'll be sacrificing a lot of power and running a lot hotter than normal.

Those figures stack up with the data I have from TVR. Normal is 8, go to 4 for unleaded but play around as there is some variation. However some of the engines were more "standard" than others and hence there is variation.

[richardpowell]

Thanks for all your information, i have now set my timing to 8 degrees but i have 3 vacuum hoses to reconnect because the last owner disconnected them, also the timing was set to about 18-22 degrees BTDC, no wounder it was running hot,does anyone know how to pipe up the vacuum hoses, one goes to the dissi advance diapham, one to the other side of the diapham and one to the air inlet manifold, are they just piped together with a tee piece.hope someone can help cheers
Pictures would be good

Edited by richardpowell on Monday 29th December 14:00

[GreenV8S]

If you have two spigots on the vac advance cannister, connect the vac line from the throttle body to the one facing away from the dizzy and leave the other one open to fresh air. Nothing else should be teed into that vacuum line. There will also be a similar vacuum line to the fuel pressure regulator. If your setup uses positive crank case ventilation you will also have a larger bore breather from the rocker cover to the intake upstream of the throttle body, and a small bore breather teed into this that connects downstream of the throttle. Finally you'll have the brake servo vac hose.

[GRIFFONMARK]

Honestjohntoo, you know what I meant and so did everyone else. Some people just have to make everything sound soooo complicated.

Cusp - a point of changing from one state to another - from the latin cuspis, a type of weak lager brewed in the Cuspian region of Greece.

Royalties of 1 shilling per book (after tax) and a signed first edition please.

Regards

Mark