Ok, so by some miracle... I have done a fix!
TL;DR - timing was wayyyy advanced, seems to have been fixed now
but I have a couple of questions, as in
bold!
- Spark plugs out (10mm spark plug socket thing)
- rotated crank pulley clockwise (21mm socket thing)
- failed to find any obvious mark bar a small nick that
might be what I was looking for
- got hold of a clean, long barbeque skewer
to gently put it into cylinder 1
- rotated the crank pulley some more and watched where the skewer stopped moving up (so Top Dead Centre)
- checked the crank pulley and Bingo! - the small nick lined up with TDC
- marked the nick with a white paint pen thing (thanks, Hobbycraft
) and also added a thicker line underneath it to aid visibility
- replaced the spark plugs, taking care not to cross-thread them
It was at this point that I connected up the timing light (taking the positive feed off the alternator bolt that should be under a cover that is missing on mine
) and set to checking the timing.
You know how the mark is supposed to be at the 10 degrees marker on the crank cover timing gauge thing (+/- 1 degree)?
Wellll...
Mine was about three-quarters of an inch off the left-hand (advance?) end of the gauge...
Given the timing advances when the revs rise (if I understand things correctly?), canoe knows exactly what the timing was running at
I duly switched off, bridged the GND and TEN on the diagnosis port, cracked the 12mm nut on the Cam Angle Sensor (PITA being so close to the bulkhead), restarted the engine and started twisting the CAS bit by bit while checking the timing each time.
I think I must have needed to twist it about half an inch or more to get the mark back onto the timing gauge, and then some more to actually get it between the 10 degree mark and the left-hand end of the gauge.
The timing mark jumps around a lot at idle, though - like it's impossible to actually pin it down to one timing mark. In the end I aimed to get the mark staying between 10 degrees and (I presume?) the fourth, 14 degrees(?) mark on the left-hand end, so hoping for an average between the two.
When I lift the revs, the mark stabilises (off the end of the gauge).
Question - is the uneven-at-idle timing mark an issue?? It seemed to run ok on a test drive, and I could actually give it some throttle without sounding like it was going to die imminently
It even took near-full power acceleration, but
it blew the plug leads off cylinders 2 and 3 the first couple of times I was guessing that perhaps I hadn't done the spark plugs up properly?? so took them out and re-threaded them slowly and carefully, before making sure to push the plug leads on firmly.
Question - I'm hoping the plug leads thing isn't a major issue?!I still don't understand how the timing was so far out - Skuzzle set it up and it was just fine after the head gasket and 14degree mod was done ages ago, but at some point within the next year after that the power band shifted from 'banging into the limiter' to 'tailing off at 6k rpm'.
Since that point it seems to have got worse, hence the ridiculous pinking needing fixing, but
why has it got worse? Surely the timing should stay fixed once set? Unless it's jumped a tooth on the cambelt? or the CAS is dying??