Rajo dual plug ignition history question

[Reno Speedster]

I have a dual plug Rajo head that will come back from the shop at some point. One of the things to work on is ignition for it. I have a Bosch front plate distributor. I see on the form that folks have adapted dual spark rotors and caps to run both sets of plugs in Rajos, which sounds like a good way to go. But, I have a rule that I won’t put anything on my car unless it or an equivalent was available in 1927. So, what was available/used for the Rajo dual plug ignition in period.

I have seen vintage Delco (I think) dual plug set ups that were used on other cars in period that use two caps, but they are really expensive and would be difficult to adapt to a T. I have several of the standard speedster books that have copies of original Rajo ads and catalogue sections, but I don’t recall seeing details on the ignition systems used. Were 8 plug distributors available for the T? Was a magneto standard? What exactly were the period options for running dual plugs?. So,

[kmatt2]

Your cut off year of, 1927 parts only, means things will not come cheep to go two spark. The two cap system you talked about is from a Stuz and they can be mounted like a side drive mag, that would fit 1927 requirement. Back in the early 1980’s I had a BB Rajo running a Bosch ZR4 mag on a cross drive, it was very fast. I don’t think the two spark Nash distributor came out until the later 1930’s, but it would look something like the more current Nissan two spark that you talked about. Back in 1927 there were many left over Bosch ZR4’s mags, 2 mags per airplane, because they had been used in WW1 trainers and in early 1920’s airplane engines that were now outdated by 1927. I think that Layden Butler had a Bosch ZR4 mag for sale not to long ago, but I could be wrong on that. I haven’t seen a Stuz system for sale in a long time. Maybe get your car running with a later system until you can get the 1927 system you really want. Good going with your project.

[speedytinc]

I am running a Stutz on a BBR. They bolt to a standard magneto mount. Bosch works well. This set up was THE set up in period. I am always looking for parts. One vendor had a used cap @ Tulare - $400. I did sell a extra complete Pierce unit(same) a few years back for a smokin good deal @ $1200. If you can find the body, later stuff can be adapted. Its an expensive way to go, unless you get really lucky.

[David Greenlees]

Morgan if you want to stay pre-1928 here are two of your choices and one the dates to 1929.

Left to right top photo: a Stutz Dual Delco and a ZR4 Bosch two-spark mag although both are expensive and hard to get in todays market place and will also need rebuilding. There are other two spark mags available at lower prices. I've used both although my first choice would be the mag but and they both workout well.

In the middle is a Nash twin-fire 8 cylinder distributor adapted to a T on an iron base for aftermarket distributor, it was 1st offered in 1929. By the time you find a good unit and a base, convert it and rebuild both it could cost about a third of the other choices. Only eight of holes in the top need wires and the other eight stay empty, although they could be wired to a ground with wires to look a little better. I used this unit in a Rajo BB in the past and it worked out fine.

In the Bottom photo: Is American Bosch mag adapter which takes the place of the original Ford generator mount. Both The Stutz Dual Delco and a ZR4 Bosch mag or any other mag need one of these, they are not inexpensive either and sell for about $500. There is one in the classified ads for sale now.

[Les Schubert]

A popular “modern conversion” is a Nissan dual plug distributor cap and rotor adapted to a Bosch T distributor. With a Onan 2 cylinder coil (which is specially designed to fire two plugs at the same time), you can run from a single set of points. I’ll take some pictures of it later today.

[Henry K. Lee]

Have used both Nissan and a dual (2 each side by side) VW Bosch 009 distributors with great results!

Hank

[Kevin Pharis]

There was also a Stutz dual ignition distributor similar to the one pictured above, but with a single cap. These units bolt up to any mag drive, but beware of rotation direction. I worked on one a while back, and had to reverse the input to work with the T mag drive. 2 sets of magnetic pickups, and a new upper plate and we were back on the road! Just hope the cap or rotor never gets damaged...

[David Greenlees]

Morgan, Here is one that slipped my mind that was made in the teens and twenties and they come up for sale now and then; it is probably the most affordable vintage dual systems today. It's a Philbrin dual 4 cylinder distributor that can be driven off either end and in either direction. They also made other single units for other cars including one for the T. Philbrin was a sponsor for the Duesenberg racing team in the teens and these units proved to be reliable, and helped them win a number of races.

The one in the bottom photo is one on a 1915 Duesenberg racing car I have done a lot of mechanical work on and prep it for vintage races for a customer. The two distributors were replaced with semi-modern Delco units by another shop before it came here 30 years ago. I had the bottom half apart then and it was in very good condition, and did it again last year and it's still in the same condition after running in about 15 race meets at high speed. Based on this experience I would recommend one for a dual setup.

[Reno Speedster]

Very interesting. I found one of the Nissan distributors and will be looking at that but keeping my eye out for a more original option.

[RajoRacer]

Here's my first set-up on my BB near 30 years ago - I've since updated to a later model Nissan with electronic modules. Back when I started building mine, a Bosch ZR4 was around $2400 rebuilt IF you could locate one !

[David Greenlees]

Here's my first set-up on my BB near 30 years ago - I've since updated to a later model Nissan with electronic modules. Back when I started building mine, a Bosch ZR4 was around $2400 rebuilt IF you could locate one !

What size or letter Winfield SR are you using and how well does it work for you? I'm looking for one to use on a T racer for vintage racing and am wondering what its throttle response is like, and will it run on cool air after its warmed up?

I have the same manifold for my BB and am looking for two of them with vertical flanges and bolt holes for a Fronty SR heads.

Yes, today ZR4 two spark mags take a while to find. I was fortunate to find one years ago and today am looking for one or two more for other T racing engines. There is good article on how to rebuild and test and rebuild them @ https://theoldmotor.com/?s=+++As+the+Magneto+Spins

[RajoRacer]

It was a NOS SRB I purchased from an old timer in California 30+ years ago. In Western Washington, it doesn't particularly appreciate the cool, moist air thus the "hot air" attachment off the header. Seems to run good albeit they're a might temperamental !

[Mike Penserini]

The distributor in my Green triple drive is a modified Delco 668, 1930 Studebaker that came with a 4 lobe cam and dual points and dual coils. It had been modified for 2 spark 4 cylinder and to fit a Bosch front plate. I had to buy the Bosch plate to get it but was delighted to find that it fit my Green Engineering plate perfectly.

[Harry Lillo]

Two questions for the group:
1) Has anyone used one of the 1960's DuCoil 4 cylinder distributorson a T?
I have one and it appears to be a relatively simple conversion to use on a front plate setup.
2) Did anyone notice that dual fire Eisemann 4 cylinder magneto that sold at a recent auction
advertised here on the forum? Looked like a good one.
Harry Lillo

[Dan McEachern]

Ducoil in Bosch Front Plate.

[Harry Lillo]

Great to see Dan.
Nice engine...........
Harry

[Reno Speedster]

What are the details for the Ducoil distributor? Maker, part number, original application, etc. it’s a better looking distributor than the Nissan.

[David Greenlees]

Ducoil in Bosch Front Plate.
0531162021.jpg

Dan, that is a very interesting distributor and it even looks old, did you set up? Who made that intake manifold?

It works on the same principal as Mike's Delco 668,1930 Studebaker distributor above. Here is what I found online about how it works: The DualCoil distributor was a fairly good idea for the times before the CD boxes. It was somewhat simple in design and had two coil towers in the distributor cap so it could send the fire of two coil's energy into the cap instead of just the energy of one. That meant by theory that the plugs got twice the spark energy. More info @ https://www.speed-talk.com/forum/viewtopic.php?t=2641

Here's a look inside of one.

[Dan McEachern]

The Ducoil distributors are essentially copies of the Delco Twin Spark design that David showed. Made as an aftermarket performance distributor in the '60 and '70s for many V-8 engines. Produced by a company called W&H and later purchased by Mr. Gasket around 1970 or so, but they discontinued the line a few years later. These used to be easy to find at swap meets etc, for not much money, but since the nostalgia hot rod thing, the price has gone up considerably. There are always a few on eBay at crazy prices. Major drawback is the cap and rotors are not produced any longer. Part of the modification to make them work on a 4 cylinder engine involves modifying the rotor by offsetting one side of it 45 degrees. In addition, the point plate needs to be re-machined so that the points can be repositioned to open simultaneously.

David- to answer your question, the intake manifold was made by a friend of mine, Bud Hand in Southern California many years ago. Bud has been gone for many years, but the parts he made live on! Not sure of how many he made, but I personally only know of one other, and it is in Illinois. This particular one (mine) has a model MB Winfield bolted to the bottom.
And yes, I modified the one in the picture, but I can't take all the credit- Vic Sala showed me how to make the modification about 40 years ago.

[David Greenlees]

Dan, Thanks for the info on the DuCoil and the manifold. This is a photo of a spare Delco distributor and cap for the Nash unit I posted earlier. It has the angled rotor you mentioned. We took it off of an engine that ran quite well in a Mercury speedster with a Rajo BB head w/twin plugs for a customer who wanted to detune it.

[Gary_in_MN]

Here is what I did on my dual plug DePaul head. 90 * bases are 1920's Dodge. I did run Model "B" dist. first but then changed to Bosch. Electronic ignition pickup in the read dist. which fires a 1/3 of a Buick coil pack. Gary in MN

[Erik Barrett]

Vintage dual spark stuff will set you back some serious cash. Here are a couple. One is Stutz and one Pierce Arrow I think.