OzVMX Forum

Clubroom => Tech Talk => Topic started by: Bamford#69 on November 10, 2014, 12:19:03 pm

Title: CZ ignition timing
Post by: Bamford#69 on November 10, 2014, 12:19:03 pm

Hi, Does anyone know the CZ ignition timing in degrees,for 250, 400,
 I can only find mm BTDC
cheers

Title: Re: CZ ignition timing
Post by: yamaico on November 10, 2014, 02:32:04 pm

If no one can help you and you know what the stroke and conrod lengths are you can calculate the ignition timing in mm BTDC by the following equation:
T=R+L x (1-cos a) - ?(L²-(R x sin a)²)
a = degrees before TDC
T = mm before TDC
R = engine stroke divided by 2 (mm)
L = conrod length (mm)

Title: Re: CZ ignition timing
Post by: Bamford#69 on November 10, 2014, 06:36:54 pm

Hi, that's what I was afraid of, but thanks
cheers

Title: Re: CZ ignition timing
Post by: Lozza on November 10, 2014, 10:47:24 pm

BAMFORD CLICK HERE (http://www.torqsoft.net/piston-position.html)  :D

Title: Re: CZ ignition timing
Post by: Bamford#69 on November 11, 2014, 08:42:04 am

Hi, thanks for that , I'll  have a crack at that.
cheers
ps,
 do you have the rear suspension travel calculator ?

Title: Re: CZ ignition timing
Post by: Bamford#69 on November 26, 2014, 07:57:13 pm

Hi, "did the sums" give or take a 'couple of seconds' it  works out both the 250 and 380 are
      22 degrees BTDC,       who'd a thunk
cheers

Title: Re: CZ ignition timing
Post by: jimg1au on November 26, 2014, 09:30:09 pm

please explain
if you know were tdc is why cant you use a micrometer.
as you said 22 deg from tdc so you must know were tdc is
jim

Title: Re: CZ ignition timing
Post by: Mick D on November 26, 2014, 10:17:16 pm

Quote from: Lozza on November 10, 2014, 10:47:24 pm

BAMFORD CLICK HERE (http://www.torqsoft.net/piston-position.html)  :D

That is a great link Lozza, kind of you to share it, thanks :)

Title: Re: CZ ignition timing
Post by: Lozza on November 26, 2014, 11:06:25 pm

I actually got it from here so I can't take any credit that goes to PCMAX

http://forum.ozvmx.com/index.php?topic=17431.msg230852#msg230852

Title: Re: CZ ignition timing
Post by: Mick D on November 26, 2014, 11:13:41 pm

Well then, instead you can take the credit for telling me to pour from an outlet point toward the bottom of the crucible(ladle) so I don't get the Dross in my casting  :)

Special secret cast filler rods for oxy welding fins back on.
So you cant see any difference in metal colour 8)

Title: Re: CZ ignition timing
Post by: Bamford#69 on November 27, 2014, 11:04:39 am

 Hi, the reason you  use a degree wheel on the crankshaft to set the timing , and finding TDC is because , when the piston moves just 0.016mm at TDC the crankshaft rotates 4 degrees ! 
Setting TDC  using a "piston stop" and degree wheel method is an accurate way to be within  0.004mm ! I'll bet  you cant do that with a screw driver down the plug hole !
cheers

Title: Re: CZ ignition timing
Post by: jimg1au on November 27, 2014, 05:03:16 pm

when i had a yellow tanker cz380 it had points ignition made up for me by lee holth czguy.i used to get tdc on my micrometer and take it to the required mm and set.it started all the time with out any problems. even when running methenol.only problem i had is when it was wet and cold the methenol is hard to get going
just my experience with cz ignitions
i have a set of cz tools if anyone wants to buy them along with som parts ect
jim