MTFCA Forum

Several years ago, I designed a dual distributor setup as the current options available are very limited an expensive. This project was shelved when COVID happened and the cost for materials skyrocketed. The design utilizes two independent Bosch 009 distributors driven by a main shaft and three separate gears. Each distributor head can be adjusted (advanced / retarded) independently to suit specific engine performance requirements. Replacement parts plentiful. The unit is designed to mount to a Bosch front plate and utilizes the same Bosch gears. I am considering a production run; however, a quantity of 50 units will be necessary to keep cost as low as possible. Please let me know if you have interest in this project. PM's, calls and text messages appreciated. Mark Chaffin (951) 805-0928

Just one disturbutor drives drives people crazy here. Two of them and they will have a total conniption. Beware.

Great for duale plug heads. Do they both turn the same direction? I once got hired because figured out that both distributors on a very old
American La France fire truck turned in opposite directions but the plug wires where set for the same direction of rotation.
Craig.

Yes. I designed this for use with out RAJO head with dual plugs. Both heads turn same direction (clockwise rotation).

This fascinating!! Would be a more-rough version be available? Would love to adapt the system to my A block.

Mark,
Perhaps we should talk about this design. Jeff H.

Not enough interest. Actually none. Big layout of cash to make 50. I have had several other projects where interest was expressed and a ton of money was spent and in the end, no one stepped up.

The cheapness of the Model T owner is once again evident. Neat idea. But would a V8 distributor accomplish the same?

RecklessKelly wrote: ↑

Tue Nov 12, 2024 8:50 pm

The cheapness of the Model T owner is once again evident. Neat idea. But would a V8 distributor accomplish the same?

Nope.

Dual propagation found a use in aviation, but mainly for safety.
In racing, did more trouble than value. Esentually, it just changes the timing by accelerating the flame front constant.

Was there a consideration of using two sets of ignition points inside one distributor?.... The dual point system will give an extended dwell. And a hotter spark.

On a 4 cylinder, you would have to operating at 10k rpm to benefit.

Geez this seems totally unnecessary.

Charlie B in N.J. wrote: ↑

Tue Nov 12, 2024 9:47 pm

Geez this seems totally unnecessary.

Not if you are running a dual plug head.

If someone has the cross-drive setup and wants to run dual ignition, buying the Tim Dickson conversion which takes the place of a magneto is a really cool set-up. I have just installed one on a 1925 Seagrave Firetruck (Continental engine) and a dual ignition unit on a 1917 Crane-Simplex 6 cylinder. Read more about it here; https://www.dicksonautomotiverestoratio ... onversions

(BTW, Tim also makes the LED light conversions for gas headlamps.)

Retson Ross wrote: ↑

Tue Nov 12, 2024 6:11 pm

This fascinating!! Would be a more-rough version be available? Would love to adapt the system to my A block.

I may have what you need. Somewhere I have an adapter that was made to use an early V8 Ford distributor on a Model-A/B engine. Basically the early V8 used two separate distributors, -each firing one bank of cylinders. Send me a PM with your contact info if you are interested.

Dual plugs on early high performance engines allowed higher compression without detonation on the low octane fuels of the day. On the fire trucks, it was probably done in the interest of reliability. In aviation applications, both combustion control and reliability were probably considerations.

I have a dual fire distributor set that has been made for about 20 years. bolts into Bosch mounts. will post pictures in a minute.

I have read in the past that sometimes when setting up, the two banks don't fire at the same time, one is just a little offset from the other.

Here is the picture.

Why not split the plug wires, so that they fire two plugs at once? It would probably require a smaller plug cap to keep the cap and rotor alive.
Or use a coil for each cylinder, one plug positive and the other one negative? You could use the body of the distributor to trigger coils. Just thinking out loud here.

I can have one ready to ship in a couple of days. $975 plus taxes and shipping. I also make a single fire one. I will post a video later.

My set up uses chevy points. And the cap is a off the shelf Nissan pickup truck cap. No way for it to be off when firing.

Here is the single fire 4 cylinder.

And the coil?

Ed Baudoux wrote: ↑

Wed Nov 13, 2024 10:19 am

Why not split the plug wires, so that they fire two plugs at once? It would probably require a smaller plug cap to keep the cap and rotor alive.

Because it would always fire the plug with the path of least resistance. Never fire both.

For my set up use a 6 volt or a 12volt depending on the the cars voltage. and will run in either direction.

Years ago I successfully adapted an 8 plug Nissan distributor to a Bosch front plate to fire a dual plug set up.

Andy

I’m planning to use a Onan 2 cylinder coil in combination with the Nissan cap and rotor to try on a dual plug T head. The Onan coil fires 2 plugs at the same time. This way all they have is points running off the camshaft and no distributor parts are needed. There may be factors I’ve overlooked but I plan to try it.
A distributor that I’ve used in the past is the Vega one as it rotates the appropriate direction and with the combination of centrifugal and vacuum timing control it negates the need to have a spark control lever. I first used this back in the’80’s on a A crank counter balanced T speedster and I was totally satisfied with it. The car is capable of 100 mph and still exists (I sold it years ago)

Les Schubert wrote: ↑

Wed Nov 13, 2024 6:42 pm

I’m planning to use a Onan 2 cylinder coil in combination with the Nissan cap and rotor to try on a dual plug T head. The Onan coil fires 2 plugs at the same time. This way all they have is points running off the camshaft and no distributor parts are needed. There may be factors I’ve overlooked but I plan to try it.
A distributor that I’ve used in the past is the Vega one as it rotates the appropriate direction and with the combination of centrifugal and vacuum timing control it negates the need to have a spark control lever. I first used this back in the’80’s on a A crank counter balanced T speedster and I was totally satisfied with it. The car is capable of 100 mph and still exists (I sold it years ago)

I assume the Onan is a center tapped coil. That is the best way. If the coil is 1.5 ohms, that should work well. You want to limit the current to 4 ampere.

However, there is no free ride. You may have dual flame fronts, but each plug will recieve 1/2 the total spark energy that a single coil of 1.5 ohms would deliver to a single plug..

I have an old mb jeep dizzy on my bosch plate. Going to try a couple different coil/ condenser combos.

I also have 3 bosch front plate distributors and an original bosch coil . I want to see how well that works.

I've been running the Mitsubishi 2 spark on my Racer for over 30 years - I did convert to electronic module maybe 20 years ago - no muss - no fuss !

Interesting. Thanks for posting.

big2bird wrote: ↑

Thu Nov 14, 2024 11:13 am

Interesting. Thanks for posting.

To muddy up those waters, ...why not run a commutator in lieu of distributors, and then use either the Onan coil -or a Harley Davidson twin coil on each cylinder's twin spark plugs??

BRENT in 10-uh-C wrote: ↑

Thu Nov 14, 2024 11:43 am

big2bird wrote: ↑

Thu Nov 14, 2024 11:13 am

Interesting. Thanks for posting.

To muddy up those waters, ...why not run a commutator in lieu of distributors, and then use either the Onan coil -or a Harley Davidson twin coil on each cylinder's twin spark plugs??

Distributor setups are inherently accurate out the box & are relatively maintenance free..

If using a timer, you still have all the pesky defects/issues each type bring.

Roller timers wear rollers fast, wear the track & bounce the roller @ higher speeds.
Anderson types need to be checked for accurate timing, but can be adjusted for accuracy.
Newday's can be off in timing, but can also be "fixed" for accurate timing.

I went thru all this to get an accurate firing ignition & determined the refurbished Newday's to be my best choice instead of caving into using a distributor for a single plug motor.

Other than needing more maintenance, 4 twin fire coils with a timer could work fine.

I’m trying to understand how a timer is supposed to fire a Onan or Harley coil?

Les Schubert wrote: ↑

Thu Nov 14, 2024 12:23 pm

I’m trying to understand how a timer is supposed to fire a Onan or Harley coil?

It's pointless.

So the Onan twin fires with a waste spark system. One plug positive, electrode to ground, and one side negative, ground to electrode. Now as designed this works fine, the firing cylinder gets the voltage it needs and the waste cylinder only uses a couple kv to jump the gap. However with both plugs in the same cylinder they are both under load. At idle with a low kv requirement, in the 5-7 kv range, this shouldn’t be a problem. However under a heavier load where the kv requirement may be 15-20 kv, does the Onan coil have the ability to reliably proved 30-40 kv? Just wondering, maybe an engineery guy knows better.


Andy

The main issue I have with this stuff is NO one publishes the inductance in Henry's.
Rarely turns ratio.

You really have to play around.

I can test this stuff this winter, but probably not till spring.

speedytinc wrote: ↑

Thu Nov 14, 2024 12:03 pm

BRENT in 10-uh-C wrote: ↑

Thu Nov 14, 2024 11:43 am

big2bird wrote: ↑

Thu Nov 14, 2024 11:13 am

Interesting. Thanks for posting.

To muddy up those waters, ...why not run a commutator in lieu of distributors, and then use either the Onan coil -or a Harley Davidson twin coil on each cylinder's twin spark plugs??

Distributor setups are inherently accurate out the box & are relatively maintenance free..

If using a timer, you still have all the pesky defects/issues each type bring.

Roller timers wear rollers fast, wear the track & bounce the roller @ higher speeds.
Anderson types need to be checked for accurate timing, but can be adjusted for accuracy.
Newday's can be off in timing, but can also be "fixed" for accurate timing.

I went thru all this to get an accurate firing ignition & determined the refurbished Newday's to be my best choice instead of caving into using a distributor for a single plug motor.

Other than needing more maintenance, 4 twin fire coils with a timer could work fine.

Yeah, I believe you and I are thinking on two different planets. When I mentioned using a commutator and twin coils I really did not mean to speak of using a Model-T timer. My apologies for misleading you. With that said and your suggestion, I definitely might consider using an original Timer housing just to camouflage the inner workings, ...but if I/we are going to this level of sophistication, I likely would use Hall effect to trigger the coil thru the ground side of the circuit. Maybe an I-Timer??

FWIW, it has been my experiences that a crank trigger set-up used in motorsports already has perfected the pesky distributor. Use the same theory inside of the 'timer case' and build a one-off commutator set-up. BTW, motorsports is not something that is new to my family. Below is a picture of me at the World Finals last weekend, ...and the young man with the sunglasses & beard to my immediate left was just elected as the newest MTFCI Board Member. Yes we play with Model-Ts, and we are known for restoring antique cars, but we also like to compete with state-of-the-art race cars.

big2bird wrote: ↑

Wed Nov 13, 2024 10:59 am

Ed Baudoux wrote: ↑

Wed Nov 13, 2024 10:19 am

Why not split the plug wires, so that they fire two plugs at once? It would probably require a smaller plug cap to keep the cap and rotor alive.

Because it would always fire the plug with the path of least resistance. Never fire both.

I suppose I typed that out before my brain gave it a review Thanks!

As I said I haven’t tried the Onan coil thing yet. But I figure in the worst case I’ll just pinch on plug in each cylinder and effectively just run on one plug but maintain the “illusion” of dual plugs. The head I have is a Gemsa and the two plugs are beside each other anyway!!

Les Schubert wrote: ↑

Thu Nov 14, 2024 7:06 pm

As I said I haven’t tried the Onan coil thing yet. But I figure in the worst case I’ll just pinch on plug in each cylinder and effectively just run on one plug but maintain the “illusion” of dual plugs. The head I have is a Gemsa and the two plugs are beside each other anyway!!

Why not a Harley Davidson coil over the Onan? There are way more H/D dealers around than Onan dealers should a coil become faulty.

Brent
Because I’ve run Oman’s for 30 years and have no experience with Harley’s. That is one of the benefits of posting on this forum