How important to have all Flywheel Magnets?

[kabona]

I have a 6 magnet flywheel

I needed to replace my old flywheel. So i bought a new one with only 5 magnets on it and that were all glued back on, but the 5 magnets were spaced out properly so the flywheel would be balanced. The guy says he works on force motors all the time and 5 magnets will still give me the spark i need. If it doesnt work then i can bring it back no problem. So i took it.

Basically my question is. Is the number of magnets and the magnet placment very critical on the flywheel? If the magnets are off set and one less magnet then there should be ,will that throw my spark off? or any other problems?

thanks

 

[jimbo_jwc]

Re: How important to have all Flywheel Magnets?

Should be less voltage /amperage for alternator at idle to charge battery .

 

[jason32038]

Re: How important to have all Flywheel Magnets?

Ask him if it will affect your tach reading at all.

 

[fucawi]

Re: How important to have all Flywheel Magnets?

you did not say what engine it is and what type of ignition ..usually the magnet poles and the poles on the stator are matched ..if it has anything other than coil/battery ignition I think you are bugggered

 

[Frank Acampora]

Re: How important to have all Flywheel Magnets?

Read my thread on "Don't second guess the factory." Yeah. you might "get away" with it but then again, you might not. The manufacturer specifies parts and pieces for a reason. Sometimes not obvious to us, but a reason, nontheless.

Very good point made above: 5 magnets will change the requency of the A/C charging the CD boxes and the 12 volt A/C frequency (before rectifier). It will change the tach reading if you take signal off the stator.

 

[jimbo_jwc]

Re: How important to have all Flywheel Magnets?

Rectifier doesn't care about frequency just changes what AC is provided to DC then its regulated to desired voltage for ignition /battery charging , I agree on tach pulse if tied into stator windings . I had problems on old Case tractor not charging at idle with accessorys on and a Old Timer fixed me up with 6 pole windings from a 4 and increased output at lower /idling rpms .You just changed rotating magnetics from 6 pole to 5 . Most alternators make 3 phase output for its more efficiant and square wave rectified has less drops to zero voltage when diode/rectifier conducts. Sorry I starting to feel like an Old Timer myself these days .

 

[Frank Acampora]

Re: How important to have all Flywheel Magnets?

I know that the rectifier is more or less independent of frequency, Jimbo, But I am not talking about charging the battery! The CD boxes however, are charged by about 250 volt A/C power from separate windings and they MAY be frequency sensitive. One side of the box charges with the positive pulse of the sine wave and the other capacitor charges with the negative portion.

As an example: I don't really see it causing a problem because at 5000 RPM with a 5 pole stator and 6 magnets the sine wave will be 500 per second and at 5 magnets it will be 411 per second. NOW, if it only takes one pulse to charge up the capacitors, then the difference will be negligable. HOWEVER: (again) If it takes multiple pulses to charge the capacitors, the lower frequency may just make a difference. Again, his problem is at cranking AND these engines MUST be cranked at something over 350 RPM to fire the plugs. So at cranking speeds with a 20% less frequency, there may be sporadic firing.

A 20 pole stator has 10 poles dedicated to battery charging and on 2 cylinder engines 5 poles are dedicated to charging ignition. the other 5 are left unwound. Three and four cylinder have two separate 5 pole windings, one dedicated to each CD box. This is for old style Force ignitions. If there are separate magnets on the flywheel, then it is a Mercury ignition. The stator has nine poles and is completely enclosed so you can not see if poles are dedicated. Suffice to say, frequency to charge the electronic ignition will still be less with only 5 magnets on the flywheel.

Not knowing the internals of the CD boxes, it is a difficult call.

BUT (again) the factory put 6, not 5 magnets on the flywheel for a reason. Do you think they would spend the extra money for a piece that was not needed? Businesses always maximise their profit by producing the product at minimum cost for quality desired. This means NOT throwing in unneeded parts.

 

[jimbo_jwc]

Re: How important to have all Flywheel Magnets?

Thanks for info my old motor power unit got replaced and I used same flywheel the only thing different was the Magna ? Old was aluminum and not sealed good and the replacement was black . I always hooked up right and wondered about spark when hooking up but it always worked 1972 with points . Look at post in OB about mayhem cause I need weight info ? Can two guys lift off ?