Author Topic: Distributor  (Read 2470 times)

Offline Camm-1

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Distributor
« on: April 11, 2014, 04:34:32 PM »
Hi all of you!
My inline six runs very good WHEN it fires on all cyl but it is some sparking here and where that it shouldnt.
I can here it in the distributor to.
Does it do something if the rotor touch the collectors in the cap?  they do touch the cap , it moves a bit when rotating.
Or should it be a little play between. :shrug:
Or maybe the spark somtimes take the way down to the undercarrige of the distributor? :thinking:
I think it is about 10mm from rotorend to the underpiece of alu.
Ove

Offline Tonyr

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Re: Distributor
« Reply #1 on: April 11, 2014, 06:38:51 PM »
Hi camm-1

The rotor should be close but not touching.
Make sure the inside of the distributor and cap are very clean.
I have a 4 cylinder engine with a clear plastic distributor.
You can see the high voltage sparks flashing inside the distributor when it gets dirty.
The terminals are close on a small 6 cylinder distributor.
Also make sure the rotor is inline with the relevant terminal when it fires.

Tony

Offline Admiral_dk

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Re: Distributor
« Reply #2 on: April 11, 2014, 06:47:26 PM »
Hi Ove

The smaller the distributor - the bigger the problems. If you can't get the distances big enough, you'll have too make a "labyrinth" from insulating material inside the distributor in order to increase the distances. 10mm. might not be enough or put this way - it's much higher resistance than firing through the sparkplugs when they are outside the cylinder, when checking, so at that point in time it works, but when inside the cylinder and under working pressure - those 10mm. might be a smaller resistance than firing through the sparkplug ....  :zap: ....  :Mad: .....  :cussing:

Best wishes.

Per

Offline PStechPaul

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Re: Distributor
« Reply #3 on: April 11, 2014, 08:07:06 PM »
I'm no expert at model engines, but I think it is also important to make sure the spark advance and dwell are such that the spark is generated only when the distributor rotor is within the sector of rotation where the contact to the plug wires is very close. If you are trying to run at very low speed with conventional points and coil, especially if the cam and points are scaled down, there will be a much smaller gap on the points and they will open more slowly. This is especially true if the points are operated by a multi-lobed cam, which has effectively smaller and slower point opening and closing.

Offline Camm-1

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Re: Distributor
« Reply #4 on: April 11, 2014, 11:09:25 PM »
Ok I can undertand to close earth points but not why the rotor not should touch the points.???

Offline PStechPaul

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Re: Distributor
« Reply #5 on: April 11, 2014, 11:28:52 PM »
Electrically, it would be ideal for the rotor to touch the contacts on the distributor. But mechanically, it would cause friction and possibly jamming as things wear, or just because of manufacturing and assembly tolerances.
 
The Model T used a roller in the distributor, so there was direct contact and no arcing. But that adds complexity and cost, and is a likely point of failure if not properly maintained. It is actually called a "timer" and operates on low voltage, which is connected to each of four vibratory spark coils which provide a continuous spark as long as the timer contact is closed. The timing was adjustable from the steering column. This system is probably ideal for very slow-running engines.
http://www.modeltcentral.com/ignitionarticlepage.html
 
« Last Edit: April 11, 2014, 11:34:06 PM by PStechPaul »

Offline Camm-1

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Re: Distributor
« Reply #6 on: April 12, 2014, 11:22:07 AM »
Thanks for advise!
I would try to turn off the points in cap to not touch at first.
It always brass dust in it cause of grinding to the points.

Offline John Hill

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Re: Distributor
« Reply #7 on: May 09, 2014, 01:20:08 AM »
The spark has to jump a small gap to the collectors and this sparking generates ionised air which is conductive and encourages sparks to jump every which way except where you want them to.  On measure you can take is to give the cap positive ventilation.