Erratic timing at +3500 rpm
Discussion
Although my engine feels like it is running okay through the rev range, I thought I would check the ignition timing.
My TDC pointer is spot on after checking with a depth gauge on cylinder 1. With the vacuum advance removed and a warm engine, the static timing moves between -6 and -8. At 3500 rpm the timing is very erratic between -25 and -35.
Does anyone know if this is normal or do I have an issue with the distributor weights, other ignition components etc or do I just have a 'cheap and nasty' strobe gun?
My TDC pointer is spot on after checking with a depth gauge on cylinder 1. With the vacuum advance removed and a warm engine, the static timing moves between -6 and -8. At 3500 rpm the timing is very erratic between -25 and -35.
Does anyone know if this is normal or do I have an issue with the distributor weights, other ignition components etc or do I just have a 'cheap and nasty' strobe gun?
Thanks for the information ChimpOnGas,
With the rotor arm removed, I was a little surprised that the toothed disc (the bit that makes/breaks the hall/proximity sensor) around the distributor shaft is able to rotate up to +/- 5 degrees. Is that normal?
What is the best way to check the slack on the timing chain?
Regards,
With the rotor arm removed, I was a little surprised that the toothed disc (the bit that makes/breaks the hall/proximity sensor) around the distributor shaft is able to rotate up to +/- 5 degrees. Is that normal?
What is the best way to check the slack on the timing chain?
Regards,
Thank you Penelope and others,
Yes, this is my issue.
As suspected, this lobe rotor should be connected to the shaft. I presume that centrifugal force my throw it in the same direction as the shaft spins, but I think I may just try setting it in the middle of it's movement and gluing in place rather than take it all apart.
Yes, this is my issue.
As suspected, this lobe rotor should be connected to the shaft. I presume that centrifugal force my throw it in the same direction as the shaft spins, but I think I may just try setting it in the middle of it's movement and gluing in place rather than take it all apart.
I set it to the mid-position of it's slack and have bonded it in place with epoxy. On start up, the the timing at base rpm and 3500 rpm is now nice and stable. Seems like my erratic timing is could be fixed 
Test drive planned for tomorrow.
Note: I have now had to adjust the timing (by rotating the dizzy anti-clockwise) to get back to the -6 degree at base idle which then produces only -20 degrees at 3500 rpm. Should I be advancing a little further?
Test drive planned for tomorrow.Note: I have now had to adjust the timing (by rotating the dizzy anti-clockwise) to get back to the -6 degree at base idle which then produces only -20 degrees at 3500 rpm. Should I be advancing a little further?
ChimpOnGas said:
You're looking for a maximum of 18 degrees of mechanical advance.
At 10 degrees at idle this will give 10 + 18 = 28 degrees at 3,250rpm when the distributor is fully advanced.
It sounds like you're only seeing 14 degrees of mechanical advance which will be a performance loser.
So how do I get the extra 4 degrees of mechanical advance?At 10 degrees at idle this will give 10 + 18 = 28 degrees at 3,250rpm when the distributor is fully advanced.
It sounds like you're only seeing 14 degrees of mechanical advance which will be a performance loser.
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