Unusual smell

[Brightness]

Brightness, I'll never forget when my old ford escort was playing up [20 yrs ago!]. I spent ages fiddling with it one day [not a mechanic, me], the wife [then girlfreind] brought me a cup of tea, and said " what's that pipe hanging off there?" Well turns out it was the vacuum advance [you wouldn't understand ] , so I pushed it back on, car went perfect. Women eh.

Huh! Who wouldn't understand? I come from a family of mechanics matey and can usually tell mechanics what's wrong with my car - they hate seeing me walk through the door

And just to prove my point....

A vacumm advance is a thingie that sorts out the ignition timing - it's to do with the engine vacuum increasing or something like that. Am I right?

 

[Richardp]

Ha! you could have googled that.

 

[Softus]

Brightness - you obviously know what it is, but I'm sure that gasmarkone was winding you up.

Interestingly (or not), "vacuum advance" is a misnomer; a better name is "vacuum ******", because the ignition timing is retarded when the vacuum is high. The purpose is eliminate pre-ignition (aka pinging).

Advance is needed to increase the BTDC angle as engine speed increases (because duration at a given angle BTDC decreases) - it used to be provided mechanically, using centrifugal forces, but these days it's all electronically.

 

[Zampa]

Hi folks,

The last couple of days we have noticed an unusual smell in the kitchen. It is only apparent in the kitchen and it is a kind of cheesy smell. We have checked behind units, under cupboards etc and cant seem to trace anything, anything in the fridge which may have aroused suspicion has been binned.

Any thoughts as to what this could be?

Thanks.

Fred west didnt do any building work there did he?

 

[keyplayer]

.

Interestingly (or not), "vacuum advance" is a misnomer; a better name is "vacuum ******", because the ignition timing is retarded when the vacuum is high. The purpose is eliminate pre-ignition (aka pinging).

Not strictly correct this. Pre ignition is the combustion of fuel air mixture before the spark has occurred caused usually by valves glowing as a result of overheating. This is not the same as excessively advanced ignition timing although both will cause pinking.

 

[Softus]

Not strictly correct this. Pre ignition is the combustion of fuel air mixture before the spark has occurred caused usually by valves glowing as a result of overheating. This is not the same as excessively advanced ignition timing although both will cause pinking.

I don't agree.

The term "pinking" is attributed to pre-ignition, i.e. combustion before spark, whatever the cause.

I described one cause of it, and you another.

 

[keyplayer]

The term "pinking" is attributed to pre-ignition, i.e. combustion before spark, whatever the cause.

Not necessarily. If the ignition timing is too far advanced you will get pinking, but combustion is still caused by the spark. This is NOT pre ignition.

 

[Softus]

In the general pursuit of staying open-minded, let's assume that you're right.

In which case, please can you tell me what pinking is, precisely, if it's not pre-ignition?

 

[keyplayer]

Pinking is the term for the actual knocking sound caused by premature combustion. (ie, the expanding gases colliding with the rising piston).
Pre ignition is one cause of this. Incorrect ignition timing or incorrect mixture are others. But this is splitting terminological hairs really.

 

[Brightness]

Ha! you could have googled that.

However did you guess ?

Mind you, I'm sure google would have a darned better explanation of it than mine

Do they have this vacuum advance on new cars? I don't really understand the workings of newer cars, Dad passed away nine years ago and retired a few years before (a brilliant mechanic who could repair anything repairable & who used to let me 'help' him when I was younger). I'm sure he'd have been fine with newer engines but I just get baffled by them

 

[Softus]

Pinking is the term for the actual knocking sound caused by premature combustion. (ie, the expanding gases colliding with the rising piston).
Pre ignition is one cause of this. Incorrect ignition timing or incorrect mixture are others. But this is splitting terminological hairs really.

May I retract? And acknowledge that the following is b******s?

The term "pinking" is attributed to pre-ignition, i.e. combustion before spark, whatever the cause.

I described one cause of it, and you another.

You stated the situation quite correctly, viz:

Pre ignition is the combustion of fuel air mixture before the spark has occurred caused usually by valves glowing as a result of overheating. This is not the same as excessively advanced ignition timing although both will cause pinking.

I apologise unreservedly. It's been a long time since I got something so utterly backwards between head and keyboard - thank you for the humbling experience.

 

[Richardp]

Its that spanner of yours, Its just too big

 

[Softus]

Maybe, but only if you think my nuts are too big