Some Harmon Collins Magic ????

[BUBBAS IGNITION]

I have written a few pots on the Harmon Collins Crab style dual coil ignition and a customer asked me some specific questions regarding the system..
Anytime the word "WHY" comes up regarding a different system you have to have a mindset change and put your self in the correct time period of the change.
We are assuming its 1946-48 and you own a hopped up flathead engine. Maybe a dirt tracker (thats where this one is going) that could possibly turn 6,000 plus engine rpm. The stock crab will ( with all new parts) allow maybe a rpm range of 5500 to 6000 , however maintaining that level for a few 50 lap feature races might require some serious maintance???????
Enter the need for a Harmon Collins dual coil distributor, this unit is pretty simple as it is two separate 4 cylinder ignition systems. Each has its own set of contact points and ignition coil. The primary side of this system uses Bendix aircraft contacts (# 10-357174 @ $104.00 per pair) platium plated contacts that will last forever with correct 3 ohm ignition coil. Each set is adjusted to .015 or 60 degrees on a dwell meter. Contacts are then set for correct spacing between cylinders. Unit uses a four lobe cam for the dual coil.
The weak point for this ignition system is the secondary sections required to allow the dual coil operation ( Dzus Fast on this board had made up new replacement rotors and secondary ring adapter). Many feel as if the high performance ignition needs high output coils and low resistance making the secondary high output!!! Totally not true as the higher output just causes the parts to fail early !!!! Using the proper coils and solid core ignition cables make this unit a very reliable unit.!

 

[Bored&Stroked]

This was my first high-performance ignition - ran really well once it was correctly setup and was extremely reliable. About the only issue I ever had was an occasional failure of a capacitor. Easy fix - and I always kept a 'spare' in the car.

 

[Jack E/NJ]

What this? Jack E/NJ

 

[BUBBAS IGNITION]

What this? Jack E/NJ

Just some camera glare i think, cleaned up old cap with wd40 and tested secondary output on machine...??

 

[TerryOH]

How much magic ya got? Actually I was able to get this together, I'm sure you would have also. I believe it sustained a violent suspension of function years ago.

 

[BUBBAS IGNITION]

How much magic ya got? Actually I was able to get this together, I'm sure you would have also. I believe it sustained a violent suspension of function years ago.

Good job Terry , yep it is amazing what some glass beads and a brass wheel can get done.

 

[Bored&Stroked]

How much magic ya got? Actually I was able to get this together, I'm sure you would have also. I believe it sustained a violent suspension of function years ago.

Nice work Terry! BTW - where are you located in Ohio? Have we met before?

Dale

 

[v8fordman]

Just wondering how you set the initial timing on one of these Harmon Collins distributors? Do you set it with a KRW timing fixture? Will it work just as it does on an original crab?

 

[BUBBAS IGNITION]

Just wondering how you set the initial timing on one of these Harmon Collins distributors? Do you set it with a KRW timing fixture? Will it work just as it does on an original crab?

My Allen distributor machine has paint marks ( copied from KRW settings) .

 

[Bored&Stroked]

Just wondering how you set the initial timing on one of these Harmon Collins distributors? Do you set it with a KRW timing fixture? Will it work just as it does on an original crab?

You have the same slotted screw on the side as with a stock 21A/Crab distributor. Also, it has the same mechanical advance and vacuum brake as the stock crab setup.

 

[birdball]

Hey bubba- good write up! Will the original vacuum brake work with the H/C or do you have to gut it to make it work with the system?

*edit* sorry Bored and Stroked, somehow I missed your post above! Good info.....

 

[BUBBAS IGNITION]

Hey bubba- good write up! Will the original vacuum brake work with the H/C or do you have to gut it to make it work with the system?

*edit* sorry Bored and Stroked, somehow I missed your post above! Good info.....

The vacuum brake and advance/retard ring are stock in the Harmon Collins and may be used as usual..
I suggest using some light tension on the vacuum brake even when not hooking up the vacuum.........

 

[blucar]

The instructions that came with my HC ignition in 1954 called for two stock '42-48 coils mounted back to back on a stock mounting bracket, still have that setup on the engine.
There use to be a tune-up shop here in Ventura that understood the HC ignitions, they are long gone, guess I'll have to send my HC to BUBBA's when it needs work.

 

[Ol' Ron]

I'm with B&S, it was also used on the first full race engine I ever built. It also preformed without any problems. However, this was a street engine that ran at the drag races. With all that said, gearing a flathead to run in the 5500/6000 has a problem with the setup or is using a fuel other than gas, maybe a blower. The 258's we ran, peeked out around 5K. bigger engines peek earlier. AS our cars went faster due to tires and suspension mods we had to back off on the gearing. It's a great learning experience, especially if you have a high stupid factor, like I did.

 

[Bored&Stroked]

With all that said, gearing a flathead to run in the 5500/6000 has a problem with the setup or is using a fuel other than gas, maybe a blower.

Ron has a good point. If you're running gas on the street and need to turn 5500 RPM, should do the trick. However, if you're running a blown setup with any sort of boost, alky or alky and nitro, just not enough energy for higher RPMs.

With all this said, on a very high performance engine (or any sort of racing) - once you go to a magneto (especially one with advance - like a Scintilla/Vertex), you'll not be going back to any single/dual coil ignition.

Keep the fun info coming Bubba!

 

[40 Deluxe]

With all this said, on a very high performance engine (or any sort of racing) - once you go to a magneto (especially one with advance - like a Scintilla/Vertex), you'll not be going back to any single/dual coil ignition.

Keep the fun info coming Bubba!

Just curious: How does a magneto compare to a modern electronic ignition? I would think that with transistors switching the coil on and off, more current can be sent to the coil, since there are no points to burn (or float). Plus, any desired dwell time can be programmed in, without any worry about point gap. Also, multiple spark discharge is available to further reduce misfire. Late model coils are capable of a reserve of 40-50,000 volts, even at much higher RPM than a flathead will ever see.
So I don't think a magneto has the advantage these days, especially when you factor in the cost and needed maintenance.

 

[Bored&Stroked]

I run both - on quite a few different engines. On our Bonneville Flathead Cadillac - we switch between a MSD ProMag to a MSD ProGrid . . . due to some classes not allowing the MSD ProGrid (it has an ECU and can control timing, etc(.

To me, it kind of comes down to complexity, wiring, nostalgic look, etc.. A plain ole' Vertex Mag is about as simple as it gets - there is nothing to screw up (or wire) - other than a kill switch. When I switch over to a MSD type ignition, I have the MSD distributor, the MSD control box and the MSD coil - and all wiring involved as such. It is a lot more stuff to setup, wire, configure, trouble shoot, etc.. With that said - if I need timing control for things like boost pressure, want to be able to use my computer to setup/manage timing curves, etc --- then the MSD has all the bells and whistles (depending on the model).

Not many folks will claim that a MSD provides a stronger spark at higher RPM - thus potentially burning more fuel and making more HP (probably the opposite). Also, the multiple spark aspects of the MSD shut off at a lower RPM - you do not have multiple sparks at higher RPMS.

Comes down to the right tool for the job (and what you like) - with cost and complexity in the mix. The one really nice thing about a mag is that once the engine is started, it needs NOTHING from the battery or charging system -- it just plain runs. There is something to be said about this aspect of a mag . . . I know once I have the engine started, very little can go wrong in my ignition system (with a mag).

 

[Tinker]

Magnetos are a real interesting setup. My only experience being old (1910-30) wico boxes for throttlers. No battery or gen/alts, just a couple small charged magnets.


https://www.youtube.com/watch?v=dx5rGdlPUoI


I worked about 5yrs in the mid 90's doing post production of nhra/ihra racing. Still go to nhra races (I'm a fan, not a racer), it's quite the experience to see in racing. Everyone should go. "Open" pits to anyone. If you have never been, you should.


Not to highjack a thread.
https://www.enginelabs.com/news/msd-keeping-eye-on-top-fuel-speeds-with-new-power-grid-system/









.

 

[40 Deluxe]

I run both - on quite a few different engines. On our Bonneville Flathead Cadillac - we switch between a MSD ProMag to a MSD ProGrid . . . due to some classes not allowing the MSD ProGrid (it has an ECU and can control timing, etc(.

To me, it kind of comes down to complexity, wiring, nostalgic look, etc.. A plain ole' Vertex Mag is about as simple as it gets - there is nothing to screw up (or wire) - other than a kill switch. When I switch over to a MSD type ignition, I have the MSD distributor, the MSD control box and the MSD coil - and all wiring involved as such. It is a lot more stuff to setup, wire, configure, trouble shoot, etc.. With that said - if I need timing control for things like boost pressure, want to be able to use my computer to setup/manage timing curves, etc --- then the MSD has all the bells and whistles (depending on the model).

Not many folks will claim that a MSD provides a stronger spark at higher RPM - thus potentially burning more fuel and making more HP (probably the opposite). Also, the multiple spark aspects of the MSD shut off at a lower RPM - you do not have multiple sparks at higher RPMS.

Comes down to the right tool for the job (and what you like) - with cost and complexity in the mix. The one really nice thing about a mag is that once the engine is started, it needs NOTHING from the battery or charging system -- it just plain runs. There is something to be said about this aspect of a mag . . . I know once I have the engine started, very little can go wrong in my ignition system (with a mag).

Thanks for the info!

 

[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