Whats the deal?
I\'ve tried the Haynes version and when i check the advance,the trailing advances far more that the leading.....to the point where the trailing seems to become the leading.This can\'t be right.....what simple thing am i missing?
I also tried this....24 degrees leading,16 trailing total advance (http://personal.riverusers.com/~yawpower/pultime.html).....and don\'t seem to have enough adjustment on the trailing to get it correct....Any bright ideas?
According to the Haynes manual the trailing does advance more than the leading. Both advance up to 10degrees on centrifugal, plus leading goes a further 7.5 degrees on vac, whilst trailing goes up to a further 15 degrees on vac. You seem to be well into the detail so I suppose you know what the Haynes says. Why can\'t you time off the yellow (leading) and red (trailing) pulley marks as per manual?
PS assume it\'s electronic ignition.
Quote from: David NockAccording to the Haynes manual the trailing does advance more than the leading. Both advance up to 10degrees on centrifugal, plus leading goes a further 7.5 degrees on vac, whilst trailing goes up to a further 15 degrees on vac. You seem to be well into the detail so I suppose you know what the Haynes says. Why can\'t you time off the yellow (leading) and red (trailing) pulley marks as per manual?
PS assume it\'s electronic ignition.
I didn\'t read that in the Haynes:o
It doesn\'t seem to run as well as it does now randomly timed on the standard settings,i wanted to time it to the settings recommended by Paul Yaw on that link.
It\'s an electronic dizzy yes,but when i disconnect the vacuum on idle,the timing doesn\'t shift at all,which is surprising considering there\'s more vacuum on idle:3Confused
Thinking about it,the trailing would advance more than the leading because you don\'t want the time gap to be the same when the engine is spining at 7000rpm and the mixture has a lot less time to ignite...
I think i\'m going to give the 24/16 mod another go.....perhaps i mis-marked the pulley?
Has anyone else timed theirs like this and does anyone else run without the vac advance?
Quote from: David NockBoth advance up to 10degrees on centrifugal, plus leading goes a further 7.5 degrees on vac, whilst trailing goes up to a further 15 degrees on vac.
So standard total advance figures are leading 17.5 btdc and trailing 5 btdc.....correct?
That\'s a fair bit of difference to the 24 and 16 quoted on that site.
Yes, your figures seem to equal the Haynes data, after adding ATDC and BTDC angles for both advances.
Would the vac advance make a big contribution at idle? I wouldn\'t have expected much of a shift when you disconnect vac at idle.
Quote from: David NockWould the vac advance make a big contribution at idle? I wouldn\'t have expected much of a shift when you disconnect vac at idle.
It\'s hard getting your head around dizzys and vac advance when you\'ve had coil packs etc for so long!
I\'m going to have to think about this.....i thought the vac advance operated at idle as thats when there is more vacuum....(ie the vac pots hold the ign retarded and as you decrease the vacuum (open the throttle) the advance increases),there\'s less vac on part throttle and none on full,only when the throttle is shut is there full vacuum so it must be doing something??
Back to school eh!:evillaugh
I\'ve read your \'YAW\' article again and they\'re saying what you\'re saying. They seem very authoritative so I think they must be right.
Apparently Paul Yaw is da bwoy with RE\'s over the pond.
So..........has anyone on here done this mod? What settings do the rotary gods of the uk recommend?
So mazdas timing marks on the pulley are 0atdc and 20atdc correct? Yet when you work out the distance between them mathematically and even measure them,they are more like 16 degrees apart.So what\'s the deal with that?
They are 15 degrees apart,20atdc and 5atdc.
With 12.5 degrees centrifugal advance the trailing is at 7.5atdc,leading at 7.5btdc.
With vacuum,trailing is at 7.5btdc,leading at 15btdc.
No bloody wonder i can\'t get it right!! Why the hell does the Haynes manual call it the tdc mark then?
Thanks Tim!:Thumbs-up