The joys of a good service (tech. q's)

[zcacogp]

ORIGINAL: mr brightside ... it was a closer call than most of Bradford knows.

Damn. Such an accident in Bradford now would be quite a good thing in many people's books ... [] Oli.

 

[poprock]

ORIGINAL: tref … why does it go better after vacuuming out the interior?

Weight savings, obviously.

 

[sawood12]

ORIGINAL: millimeep Now, jumping across a spark plug gap, that's under high pressure as the engine is reaching peak compression is really hard work

Not sure that is the case is it? High pressure air means that the distance between the molecules is less which should promote the formation of the spark - i.e. smaller gap between molecules. For example it would be impossible for a spark to form in a vacuum. I always thought that the issue with sparks 'blowing out' is due to turbulance in the combustion chamber. Ideally the air in the combustion chamber should be still or the plasma will not be stable. You are right in electricity is lazy and will always take the path of least resistance - which is often through old and tired insulation of HT leads. When I replaced my HT leads 2 yrs ago the insualtion on the ones I removed was so brittle and oxidized it just crumbled in my fingers. I'm surprised I wasn't experiencing any adverse running.

 

[Stu Alderson]

While I have no scientific proof either way, I must agree with Oli, that a large %age of starting problems is down to warn ignition bits n bobs. Harking back to the days prior to Electronic/Transistorized ignition when I ran a 1340 Cooper S (and it was heavily breathed on with 8 port head etc) it ran so much better on Beru plugs n points than Champion/Lucas OEM parts, I then changed the NGK and again not only did it feel smoother but it was more economical - Moenchengladbach to Durham on one tank (2 x 5.5gals) was quite remarkable, especially has I had to replace the NEW front tyres when I got to Durham....

 

[944Turbo]

My theory is the spark will be most advanced with a new cap and rotor arm, then as it corrodes the 'leading edge' of the terminals the spark will become retarded relative to this working towards the trailing edge of the terminals (retarding ignition will usually reduce the power). Once the terminal is fully corroded the spark is going to take longer to start its jump from rotor arm to cap as it will require more build up of energy before making the jump. I always argued for good oil that will retain its grade longer - not sure I could tell the difference between good and bad oil though just by driving. Tony

 

[944 man]

ORIGINAL: zcacogp

ORIGINAL: mr brightside ... it was a closer call than most of Bradford knows.

Damn. Such an accident in Bradford now would be quite a good thing in many people's books ... [] Oli.

Too right. Whilst I agree with John Betjeman about Slough, I am certain that he cant ever have seen Bradford! []

 

[Neil Haughey]

ORIGINAL: 944Turbo My theory is the spark will be most advanced with a new cap and rotor arm, then as it corrodes the 'leading edge' of the terminals the spark will become retarded relative to this working towards the trailing edge of the terminals (retarding ignition will usually reduce the power). Once the terminal is fully corroded the spark is going to take longer to start its jump from rotor arm to cap as it will require more build up of energy before making the jump. I always argued for good oil that will retain its grade longer - not sure I could tell the difference between good and bad oil though just by driving. Tony

Agreed, this is definitely how I see it with regards to ignition. My anecdotal proof is that immediately after replacing the cap and plugs the car seemed to run on much more and requires hardly any throttle at all to get moving, the running on effect has reduced but the car still needs only a crack open of throttle to accelerate at normal rates. Before the new cap and plugs it needed a good inch of throttle to really do much.