Series 3 Ignition timing 2.25 petrol

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Landy1979

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35
Location
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Hello I have been having a knocking/pinging noise I have been doing a lot to try and fix the problem.
I started by replacing the ignition system to an electric one, the fuel pump, entire exhaust, gearstick bushing ect.

Nothing seemed to change it at all so I tried changing the timing from tdc to 6 btdc it made a a lot louder so I went the other way and 6 atdc and it helped but has the made the car a lot less responsive and there still is a pinging/ knocking noise. Has anyone got any ideas why it is pinging and what should the factory timing be for a 1979 emission controlled 2.25 petrol
 
The noise you describe is usually a symptom of mis-timing but since you have tried all permutations of timing it must be something else. Pinking is usually caused by carbon in the combustion chamber getting red hot and causing preignition. Does the engine tend to run on for a second or two when you turn off the ignitions? Take the spark plugs out and tell us what they look like.

Col
 
Colthebrummie said:
The noise you describe is usually a symptom of mis-timing but since you have tried all permutations of timing it must be something else. Pinking is usually caused by carbon in the combustion chamber getting red hot and causing preignition. Does the engine tend to run on for a second or two when you turn off the ignitions? Take the spark plugs out and tell us what they look like.

Col
Click to expand...
Okay I'll get round do doing that, I took the head off and cleaned all the carbon about a year and 7000 miles ago but it was backfiring when the condenser went which I guess could have build up carbon. But even if that was the problem why would ignition timing effect how loud the pinging is? Thanks
 
Why not by a endoscope so you can take a look through the spark plug holes , can be got at a reasonable price nowadays.
 
Landy1979 said:
Okay I'll give it a try! What is the timing ment to be on one of these engines? Because I just can't see why it would be atdc
Click to expand...
tdc static 6 degrees running at idle, if it runs better at atdc youve an issue that needs sorting check timing,tappets,ignition system and carb
 
jamesmartin said:
tdc static 6 degrees running at idle, if it runs better at atdc youve an issue that needs sorting check timing,tappets,ignition system and carb
Click to expand...
Right okay well the carb and the ignition system are new and I have recently done the tappets. So what would you suggest now?
 
I probably don't need to tell you this but the point of altering the timing from the manufacturers setting is to allow for wear within the engine or different octane ratings of fuel. Normally, when the spark plug produces it's spark it takes a fraction of a second for the air/fuel mix to fully combust and ideally full combustion should occur at tdc or a degree or two after. 6 degrees atdc means by the time full combustion takes place, the piston is already on its way down and some efficiency is lost. If full combustion happens too much before tdc the energy from the combustion is trying to stop the piston getting to the top of its stroke and this causes engine knock and will eventually damage the engine. If the big or little ends are already worn excessively the engine will knock.
If you think your engine is in good order, e.g. big and little ends ok I would do a compression test to see if there is a problem with one or more cylinders. Worn cam followers can also cause pinking type noise. When you set the tappets, did you notice if the thread on the adjusters were all more or less the same?

Col
 
Colthebrummie said:
I probably don't need to tell you this but the point of altering the timing from the manufacturers setting is to allow for wear within the engine or different octane ratings of fuel. Normally, when the spark plug produces it's spark it takes a fraction of a second for the air/fuel mix to fully combust and ideally full combustion should occur at tdc or a degree or two after. 6 degrees atdc means by the time full combustion takes place, the piston is already on its way down and some efficiency is lost. If full combustion happens too much before tdc the energy from the combustion is trying to stop the piston getting to the top of its stroke and this causes engine knock and will eventually damage the engine. If the big or little ends are already worn excessively the engine will knock.
If you think your engine is in good order, e.g. big and little ends ok I would do a compression test to see if there is a problem with one or more cylinders. Worn cam followers can also cause pinking type noise. When you set the tappets, did you notice if the thread on the adjusters were all more or less the same?

Col
Click to expand...
Okay I believe all the ends are in good shape because this noise only happended after the head gasket was done, I didn't properly check if all the threads looked the same length but I can check them soon if that would help. Thanks
 
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