Pinking

Hello all,

At the weekend I ended up resetting my timing again after moving the distributor. This time I thought I'd try advancing further than usual to see what effects I got.

I normally run between 8 and 10 degrees advanace (set at <600rpm and vac disconnected) this time I've tried 15 degrees.

It runs a fair bit more lively and wants to rev up nicely but pinks very slightly under mild rpm/load. Question is how much damage will this do on a Landy? (Mixture at this rpm/load is 14.6-14.8 with slight throttle up hill in 4th) running regular BP 95RON.

I used to have an old Ford Escort that did this and it never did it the slightest bit of harm (head off and no sign of any damage to pistons or valves).

The pinking is like the sound of very faint drizzle on a tent not the full on hailstones on a brick-****house roof that I've heard on other over advacned engines.

So question is do I go back a few degrees or enjoy the benefits and take the risk?

D

With the hills around Hebden, I'd be inclined to back it off to between 6 & 10 degrees BTDC.

If I remember correctly you have the 2 1/4 injun, and they don't like to be advanced too far because as you accelerate you are advancing your spark even more!

With mine, I got it to the stage where it ran perfectly just before the pinking stage, so tickle your mixture and ferkle your timing until you get it right.

Tuning and engine is like tuning a guitar, those with experience can do it by ear, whilst others need external help!

I would say retard. Now about the timing, pinking is always bad and will cause damage eventually just a question of how long.
If it pinks under mild load, what's it going to do under heavy load like towing up a hill?

I don't know what its going to do, not seen any evidence that it does cause damage when its mild hence the question. If I back it off I loose performance at low and high RPM where there's not really enough advance. I'll check my spark plugs for sparkly bits of metal!

Do you know if the auto-advance and your counter-weights are working properly?

Is the vacuum line clear?

It almost sounds as though it is running on the static setup if you have managed to get it running at 15 BTDC, which is about where it should advance to on acceleration!

Oldseadog said:

Do you know if the auto-advance and your counter-weights are working properly?

Is the vacuum line clear?

It almost sounds as though it is running on the static setup if you have managed to get it running at 15 BTDC, which is about where it should advance to on acceleration!

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Timing is off and cheap petrol will cause that. As said ^^^

Common Reasons for Engine Pinging

Improper Combustion Process
An engine can ping (or knock) due to an improper combustion process. A "spark knock" is the result of combustion occurring too early. Early combustion can occur from carbon buildup inside the combustion chamber, a lean air/fuel mixture, and advanced ignition timing (spark plug firing too soon). In a properly-firing cylinder, the spark plug ignites the air/fuel mixture and a flame front starts on one side of the piston and burns across the top to the other side, which creates a rapid and evenly-expanding gas that pushes down on the top of the piston. When the air/fuel mixture is ignited prior to the spark plug firing, the two flame fronts collide, causing the pinging/knocking noise.

Engine Is Too Hot
An engine can ping because it is too hot. This is another uneven combustion scenario that is caused by the air-to-fuel mixture "lighting off" by itself. If the cooling system does not keep the engine's combustion chamber temperature in check, the air-to-fuel mixture will begin to spontaneously explode. This is also called "pre-ignition."

Improper Gasoline Octane
In addition to cooling system problems, pinging can be caused by improper gasoline octane, an overly lean air-to-fuel mixture, or a lack of proper exhaust gas recirculation. The exhaust gas recirculation system (EGR) was created to neutralize engine pinging by adding a small amount of exhaust gas to the air-to-fuel mixture going in to the combustion process, which limits the peak combustion chamber temperature.

Weights and vacuum advance are working perfectly...I know _why_ its pinging, I've advanced the timing by about 10 more degrees than most would. I just want to know if it is likely to eat the engine in a matter of minutes, days, years, nevers.

It runs better with it advanced and I might leave it like that - like I said my old Escort used to sound like it was eating a bag of Pork Scratchings all the way to Newcastle and back every week and was fine until some scratter drove it into a bridge!

It's not some ally head/block made out of chees I suppose its just the pistons that are likely to not like it up em.

The advance curve of the standard dissy is pretty straightforward and probably wants to be altered OR I could maybe make the mid-range leaner or richer but I'd rather not....what I really ought to do is pull my finger out of my bum and fit the megasquirt that's been lying around in my workshop for the past two years...

BTW: CORRECT mixture is more likely to promote pinking, its more likely to cause damage if the mixture is lean. Pinging more likely when vacuum is working....

few hundred miles and you could have holes burned into the pistions

Take a trip up Birchcliff Road to Dodnaze and see how it performs.

You should be able to get all the way up from Stubbins School in third gear with no problems

When you come back down you shouldn't get any backfire at all.

If you can't get up or you are backfiring, your setup is wrong!!

Aye it will toddle up in third no problem even if the timing is a good way retarded the ACR cam sees to that...

Thor, is that from experience on a Landy?

dominicbeesley said:

Aye it will toddle up in third no problem even if the timing is a good way retarded the ACR cam sees to that...

Thor, is that from experience on a Landy?

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If you really insist on keeping your timing that advanced you'd be best trying some octane booster. Constant pinking is never good, some engines take it better than others but it's never good.

dominicbeesley said:

Aye it will toddle up in third no problem even if the timing is a good way retarded the ACR cam sees to that...

Thor, is that from experience on a Landy?

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What the fook makes a difference spark knock in any petrol engine will melt and fook up the pistons, with bad timing as you have what is the point you trying to prove.

you are starting to respond like a retarded gibbon

dominicbeesley said:

Aye it will toddle up in third no problem even if the timing is a good way retarded the ACR cam sees to that...

Thor, is that from experience on a Landy?

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Thor1950 said:

What the fook makes a difference spark knock in any petrol engine will melt and fook up the pistons, with bad timing as you have what is the point you trying to prove.

you are starting to respond like a retarded gibbon

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Well said Mr Thor.
:hysterically_laughi:hysterically_laughi

Just keep backing it off ever so slightly so that the pinking stops, that will be the best place for the timing to be, sod the degreees

Fair play. Just put it back to twelve and it sounds a bit less pinky (hard to hear it above road noise, rattles etc) but doesn't drive as nice. To be honest I'm beginning to suspect my timing gun of lying so will static time it next time I get a chance. I do know that the timing marks are bang on as I reset them with a DTI when I did the cams so they're within 1/2 a degree...

landowner said:

Just keep backing it off ever so slightly so that the pinking stops, that will be the best place for the timing to be, sod the degreees

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That's how we used to do it back in the good old days, now sadly a thing of the past.

Soloby Rob said:

Well said Mr Thor.
:hysterically_laughi:hysterically_laughi

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I try

Its hard to tell where the pinking stops (due to all the other noises and slight leak in exhaust manifold gasket) it just gradually gets less - it's never been _bad_. I just pulled the plugs and couldn't see any bits of metal flakes...I think I'll leave it at 12 degrees until I next fill up just been for another quick blast and if it is still pinking its not loud.

Thanks lads for all the replies and I'll post back when I get a hole in my piston!

Soloby Rob said:

That's how we used to do it back in the good old days, now sadly a thing of the past.

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set timing as book says at what rpm they say......... then run the rpms up to 3,000 and see if the timing is advancing. a slight vacuum leak will fook you