Some Harmon Collins Magic ????

[BUBBAS IGNITION]

Originally Posted by cobbie

Just wondering, does any one of you experts have a Idea of a value of a Harmon Collins dual point dual coil Distributor in good condition of course it needs a rotor and cap.

Cobbie

About $200 needing set up with rotor and cap.....

[BUBBAS IGNITION]

Heres the deal with a magneto.

It generates its own primary voltage and increases as the rpm goes up.
Also it fires negative then positive as the contacts break so its kinda two four cylinder units in one case.
Not only does a mag increase the voltage with rpm the current applied also increases. NHRA has rules to prevent top fuel mags from exceeeding 45 amps !!!!!

On the other side the engine has to crank pretty fast to fire up a magneto then plug gap needs to stay down .018-.020.
A magneto action is pretty violent and requires some maintance and care.....
Over the years the magnets in the mag loose some power......

But when its all said and done they do look cool.........

[Bored&Stroked]

Here are some other things to note about magnetos.

One thing to note is that there is a big difference between an old Harman-Collings or Vertex or Mallory Super Mag 1 . . . versus computer controlled modern MSD ProMags. As Bubba noted - the top-line ProMags generate 44 amps each - and every top-fuel motor runs TWO of them . . . with dual plug heads. It takes an extreme amount of energy to a light/fire a solid column of Nitro with 50+ lbs of boost on top of it. (Though - you can't cross-compare the Amp ratings between older Vertex/Mallory Mags and MSD ProMags - the technology is quite different . . . and I won't try to get into it here).

On Vertex style mags - a stock magneto generates about 2 amps and has magnets that need to be charged after a certain amount of usage (same with Harman Collins). Most racers have their mags serviced every season - with magnets recharged if necessary. Most old "ebay - swap meet mags" - need to be recharged and potentially need new coils, points, etc.. Rarely do you just buy em and run em.

As guys started running Alky/Nitro, higher compression ratios, high boost and much higher RPMs, the stock Vertex units didn't generate enough energy. So, the aftermarket guys started putting different rare-earth/neo magnets in them, different windings, different coils (external), etc.. Basically - to generate more spark energy for racing.

When we first ran the FlatCad at Bonneville (on gas) we ran updated Vertex Magnetos that Spud Miller at FIE updated for us. As we switched over to 100% alky, the fuel volume doubles and we switched to a MSD ProMag 20 amp unit. We also went to a crank-trigger setup (using a Top-Fuel trigger) along with a MSD ProGrid timing control. There was a very noticeable difference on how the engine ran with the 20 Amp ProMag versus the 4 amp "hot-rodded" Vertex. It just burned more fuel under heavy boost. Word of warning -- then you make changes like this, be prepared to change your tune . . . as the motor is burning more fuel and your tune changes.

Plug gaps are a big deal with magnetos - much more so than with our stock points-type ignitions. A typical Vertex magneto runs about a .020 plug gap. When we first switched to a ProMag, I setup the plugs like I did for the Vertex. You might be able to start the engine ONCE with those plug-gaps . . . or maybe it wouldn't start at all. We scratched our heads and talked to the Gurus (one of which lives about 1000 yards from me). He told us to lower our plug gaps with the new 20 Amp mag to .011 to .012. This cured all our issues and the engine ran like a beast. As he explained "a ProMag is different than your old Vertex mags . . . it doesn't generate the initial voltage to 'jump the gap' like a Vertex does . . . it needs a much smaller gap. Once the spark starts to jump the gap, then it is followed up with a HUGE amount of amperage . . . which burns the fuel more completely than any of your older mags". Guys in top-fuel are running spark plug gaps closer to .010 (even smaller).

Now back to rare-earth/NEO mags: When you have a Vertex updated to rare-earth magnets, you no longer have to have the magnets recharged . . . they hold their charge. While this costs a few bucks (the upgrade), it does add a certain amount of reliability to the mix - as your mag doesn't lose it's charge over time (like a stock Vertex or old Harman Collins mag does).

Okay - enough on mags for today! As you can tell . . . I'm a bit of a magneto zealot - have quite a few of the dumb things and have a test machine to run them on.

Here is a short video of my 'Frankenstein' magneto test machine - based on something that my old friend Joe Hunt (Magneto Wizard) made to test his magnetos. He showed it to me when I was about 16 years old - decided to make my own version about 40 years later. I was fortunate that these pioneers spent time with me and answered all my sometimes very dumb questions! LOL

https://www.youtube.com/watch?v=3xduaVyzx10

Note: This machine works fine for Harman Collins, Vertex and older Mallory mags - it won't even begin to turn a MSD ProMag. I'm building a new setup to test my ProMags using my LATHE to turn the dumb things! On a 44 amp ProMag, you basically can't grab the thing by hand and turn it - the magnets are way too strong.

[Lawrie]

we run an MSD on our dragster,two setups ,as we have twin plug heads (home made) ,we use a crank trigger ,and surface gap plugs,
so far its been trouble free.
Lawrie