Dizzy confusion

[beanpole]

Guys,

The attached picture tries to explain my confusion. Basically I have replaced my dizzy guts, (35DE, with optronic, but the relationship of the rotor arm to the ‘trigger’ point does not match with the original and I think this is causing me some problems.

The rotor arm normally sits between two ferrite rods, see image on left, as both the ferrite rod disk and the rotor arm can only be fixed in one position, but with the electronic system the rotor arm is directly over one of the chopper gaps. I would have thought the rotor arm should still be between two of the ‘gaps’.

Steve


x(

[Bernie]

I don't have that setup, but I imagine you will need to re-do the basic timing. Put the engine at No1 TDC, then move to around 8 degrees BTDC. Loosen the distributor bolt and set it at the trigger point, then re-tighten. With any luck, this will let you start, and then you need to set accurately with a timimg light.

[russell_ram]

Not sure that your picture helps much but working from your word description:

Points systems work by breaking the current in the coil as they open to trigger the spark generation.

Electronic systems work in the opposite way, that is, a positive signal from the trigger causes the electronics (amplifier) to fire the coil. Hence the eight lobed rotor in the original lucas setup fires the coil eight times per distributor rev as the lobes pass the inductive pickup. In your optronic unit I would expect also that this triggers of positve spikes in the output signal from the pickup, in this case an optical sensor. This gives positve signal when light is present, that is when the sensor is in a 'gap' in the plate.

Therefore a 'gap in the optical sensor plate' is equal to 'a lobe in the lucas rotor' and these should be in the same orientation for a given rotor arm position.

any help?

Russ

[beanpole]

Definitely


Russ,

Yep, the gaps which triggers the fire, are definitely not in the same orientation as the ferrite rods are with the rotor arm. The rotor arm on the ferrite rod original system is between two ferrite rods, where as on the optronic system the rotor arm sits over one of the gaps.

If I simply replace one with the other it is quite noticeable.

This means that when the gap is in position to 'fire' the rotor arm is further round than it would be normally, playing havoc with the timing.

Steve
:}

[TINKA]

Hi Steve if you think about it all you really need to do is twist your distributor around untill it all lines up with your new system in place and all will work as before The only thing that hav happened with the new system you have fitted if because the trigger is in slightly a different place is changt the timing slightly

Hope this helps Martin

[TINKA]

Hi Steve if you think about it all you really need to do is twist your distributor around untill it all lines up with your new system in place and all will work as before The only thing that hav happened with the new system you have fitted if because the trigger is in slightly a different place is changt the timing slightly

Hope this helps Martin

[beanpole]

Is it possible to get the RV8 running on the wrong firing order?.

Just wondered as I have found number 4 plug is dead and probably has been from the start, probably explains why I thought it wouldn't start very well and run 'lumpy'. I just wondered if me advancing the dizzy so much to compensate was helping it start on the wrong firing order.

Sorry for all the questions guys, hope I'm not being too much of a pain.

Steve

[TINKA]

Steve, you can't run the engine with the wrong firing order as either the pistons would not be at the top of there strokes or the valves would not be in the right position. Are your distributor cap, rotor arm, spark plugs, and HT leads all new. If not I would suggest that this is a good place to start. As far as the timing position goes with the old and new ignition system, just for get all that you have done and start from the beginning. Get the rough position right and as soon as it is running disconnect the vac advance hose and plug it so it is not just sucking air, then with your timing light set the timing to 10 deg to start with and then go from there with fine tuning.

Hope this helps, and best of luck :tu :tu :tu :tu

Martin :7 :7 :7 :7