Timing light

A

Aroundtoit

New member
Hi
Got new ignition installed  on 3cl but I was wondering if I can still confirm with a timing light for the TDC?
And which marks to use,advance is working when reving,,
I seem to have irregular light strobe with the motor running,I must be getting spark as it idles and revs
but 1 and 3 should spark at the same time right?
Is there a bad earth (or easy solution?)
should there be a consistant spark showing easily read on tdc marks?

Any pics?
cheers
Getting there........
Nig
 
Sort of depends how good your strobe lamp is. I use a Snap On programmable strobe so only have to make a mark for tdc and dial the advance figure into the strobe, I do this for a living so the expense of such a sweet tool  is justified. If you have a non advancing strobe you will need to make a mark that corresponds with the full advance timing you are aiming for. Do not trust the factory marks, establish true tdc with a piston stop and make your timing marks based on that, full advance mark can then be established either with a degree wheel or simply extrapolated from the circumference of the alternator rotor, for example piD2 / 360 x 28 will give you 28 degrees as a linear measurement on the surface of the rotor.

      Keith
 
Or you can do it graphically,draw a circle the dia of the flywheel,mark an angle of the desired degrees with a protractor from the centre and where this intersects with the circle is the distance required.
 
laverdakeith said:
,, for example piD2 / 360 x 28 will give you 28 degrees as a linear measurement on the surface of the rotor.
Click to expand...
& the significance of the '2' is ??  if D is the diameter, not the radius.
& ya brackets?
me guess is  (Pi x Diameter) x (advance degrees / 360)

Aroundtoit said:
I seem to have irregular light strobe with the motor running, 
Click to expand...
a 'normal' strobe flash can jump around a bit, particularly at low revs.  well, they do for me.  that's why i borrow the Redax strobe, like Keith has described.  a choice bit of gear!
Aroundtoit said:
but 1 and 3 should spark at the same time right?
Click to expand...
correct
Aroundtoit said:
should there be a consistant spark showing easily read on tdc marks? 
Click to expand...
no.  as per Keith's & Phil's comments.  & i reckon it depends on ya definition of 'easy' & 'consistent'.

Mark
 
Recall reading somewhere here that by measuring 'backwards' from the TDC mark using a piece of zip tie cut to the precise length gives the advance mark for strobing. Can't remeber what the length was for a Witt equipped 180 ?
  Stuart
 
Although it is scorned upon by most, the depth guage through the plug hole works well enough. 

Determine TDC by turning the engine past TDC a bit with a caliper depth guage inserted vertically through the plug bore and zeroing it.  Turn the engine backwards a bit without moving the depth guage, push it back to the piston top and turn forwards again.  Measure 7mm BTDC which equals 32?, the stock ignition timing.  You can then mark your flywheel at the corresponding mark on the casing and use this as a base line.  The DMC curves #1-5 use 32? full advance.  Once you have adjusted the timing to these marks, you use the switch in the DMC box to further adjust timing to your needs.

This method is quick and easy, checking with piston stop and degree wheel will only confirm that the markings are well within the ballpark.

piet
 
What is the correct timing for a 3C, the Green Book mentions both 29 deg for the CDI ignition and 33 deg for the BTZ system. I cant see why different systems would have different full advance, you would think they would be the same. I have just fitted a new system from Redax, it is a great system however even Red contradicts himself on timing in his notes.
 
Aroundtoit said:
Hi
Got new ignition installed  on 3cl but I was wondering if I can still confirm with a timing light for the TDC?
And which marks to use,advance is working when reving,,
I seem to have irregular light strobe with the motor running,I must be getting spark as it idles and revs
but 1 and 3 should spark at the same time right?
Is there a bad earth (or easy solution?)
should there be a consistant spark showing easily read on tdc marks?

Any pics?
cheers
Click to expand...

I connect to an external power source when I use a strobe,eg. free standing battery or battery charger.
It takes one more question out of the equation.

hth
 
I am in the process of checking my timing,it was returned to the aproxamate oiganal setting after doing the Stater sprag.Been reading John Wilsons instruction manual and for the 2 recommended curves there is also a differance.Curve 2 is at 12 deg at idle and 36deg at full advance at 6000rpm,curve 3 is also at 12 deg at idle but then goes to 38deg at 4000rpms.The common denominator is the 12 deg at idle so I am setting it there and then checking where full advance ends up.No idea if thats apropreate for other systems.
 
ay Vince,  i'm guessing ya got a copy of the IIS advance curves ??

i would like a copy, coz me Miss J has been running an IIS for years, & i know nothing about the IIS advance curves.
has been running good,  but if she starts to ping too much during a hot dry summer,  i just retard the pick-up plate by a couple of degrees. 
cheers,  Mark

<edit>  ok, maybe a bloke could just measure wot it farken does?  but i ain't looking for things to do.  8)
 
Mark PM me your home address and I will post them up to you,tried scanning them but not a hope
Vince
 
Thats good as my envelope supply must be next to my dead stop,both are missing.I suppose these curves might be helpful with the newer systems as well,the 2 curves John used are considerably different to each other.
 
  I cant see why different systems would have different full advance, you would think they would be the same. I have just fitted a new system from
Click to expand...

The CDI system gives a much better spark so combustion can take place quicker - so piston can be nearer TDC. Out of all the systems I preferred to race with the old CDI unit - needs no battery either - Regards - Phil
 
sfcpiet said:
Although it is scorned upon by most, the depth guage through the plug hole works well enough. 
...
This method is quick and easy, checking with piston stop and degree wheel will only confirm that the markings are well within the ballpark.
Click to expand...

Did not know this method.

Thanks Piet  (bigthumb)

St?phane
 
JC131 said:
What is the correct timing for a 3C, the Green Book mentions both 29 deg for the CDI ignition and 33 deg for the BTZ system. I cant see why different systems would have different full advance, you would think they would be the same. I have just fitted a new system from Redax, it is a great system however even Red contradicts himself on timing in his notes.
Click to expand...

I have found stock spec 9:1CR triples to run fine with full advance at 32? BTDC as specified by the factory, irrelevant which ignition system is fitted.  Even the Corsa/SFC1000 engines were specified at 32?, despite the stock hi-comp pistons.  Raise CR and/or increase valve sizes or capacity, you might require different figures.

With increasing combustion efficiency, full advance can be reduced in some cases.  My 3C currently runs ignition advance at 27?BTDC, 10.something:1 CR 78mm pistons, 36mm carbs, ported Corsa spec head with dual plugs.  Haven't put it on a dyno yet, but it feels as if it pushes out at least 10 ponies more than my old motor, which still put out 95 at the crank with 60000km and quite a bit of rust on the bores.

piet
 
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