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Will a twin dizzy front cover bolt onto a 20b. I would need to deal with clearance on the water pump, electric pump or? Would the E-shaft gear for the angle sensor match up with the twin dizzies?
Thinking of a conversion of twin dizzies for na electronic ignition and a carb set up.
There are single electronic dizzy conversions for 20b, RB from memory have them.
Any particular reason for needing the twin dizzy front cover other than electronic ignition on a carb setup?
The twin dizzy option came up as a thought for a na carbed motor.
The single dizzy conversion looked harder than 2 simpler small dizzies.
I don't see the need for a third dizzy. Stick with a leading and trailing dizzy. Convert them to electronic ignition and fab a cap for 3 rotors. Equally spaced around the cap the double ended rotor should give 6 hits per dizzy rotation instead of the 4 for the twin dizzy.
Dizzy would need to be set up for advance, but the na dizzies may be in the ballpark to start with.
Triple webber would need custom intake.
Besides the car originaly came with a twin dizzy. I've tossed this idea around for a 13b. The additional cap work and making sure the cooling system is enough would be the extra work. That and making sure the diff in the car can take the power up grade.
Technically you would need a triple dizzy for a 20B, unless you are planning something that I am not taking into consideration.
One is leading, one is trailing, not one is front and one is rear.
The neat thing about this setup is that you can easily set the points with the engine running!
You can do it on a siamese distributor too but you need to shuffle wires around so the leading plugs are fired by the coils, not through the distributor. Then you can take the cap off and mess with dwell on a live patient!
This is 2017 in a few hours. Get some fuel injection. It boggles my mind that anyone would take a 20b and put a carb on it. Get a decent ECU with fuel injection and ignition control.
Well if you have an old school car and like to play with the build as much as the driving then messing with a carb and putting something together in a way it was never intended too has an appeal.
I stayed with the 12a half bridge originally rather than a 13b cause it came with a 12a. Eventually I swapped the old ribcage 4 speed for a 5 speed with overdrive☺ Now I crave more power.
Everything I drive has at least one carb. FI not my specialty. Stick with what you know. Same for forced induction.
I've tossed the idea around for a twin dizzy 13b for a while. Maybe I need to convert over a set of twin dizzies with an electric water pump conversion and mount it on a full bridge 12a for a proof of principle. I don't have a 20b laying around, but plenty of old 12a's occupy space in my shop.
I have an idea how to make this work, but im not real familiar with twin dizzy firsthand.
Can a single 12A 13B dizzy fit in a twin cover? The reason im asking because im not sure how easy it is to get the twin distributors. I would rather modify something that's commonly available and not ruin rare parts.
I see the twin cover has a length "spacer" with lock stud on top, are the single distributors a different length then the twin distributors?
The twin dizzy is smaller than the single. Two singles would be crowded
The twin dizzy is a two part set up. There is a lower portion with the gear for the e shaft and an upper section with the rest of the dizzy. The shaft is keyed where they meet. By moving the top and bottom sections relative to each other adjusts timing.
The buiseness end of the dizzy that needs to be modified is a small shaft and flange that receives the springs for the weights. Stock shaft has a 4 lobe cam for the points, it needs to receive the little star magnet. 4 for 2 rotor, 6 star for a 20b.
Bigger mod will be an alternate mount for a water pump. The twin dizzy cover interferes with the water pump on the "newer" engines. I lose the alternator mount so it can go down where the old air pump was. No turbo in the way. Soon the top of the engine would look pretty bare. A couple of small dizzies and a carb sticking up, otherwise all motor.
I can't beleive how many rotary engine cars I see where there is no motor to be seen. Just a bunch of stuff!
I know how rotary distributors work just not familiar with a side by side comparison twin vs single distributor.
The size of the cap from a single is not my concern at the moment. I want to know if single will fit in the twin hole and be functional. The stuff on top will be modded.
I'll have to pull out a couple to compare them. Have a box of old dizzies someplace. May just pull one from a twin dizzy keg.
One question is if if the single dizzy fits the twin dizzy hole. The other question is if the gears interchange at the end of the shaft. Would probably need to use the original twin dizzy gears. On the twins they spin on opposite directions as they are on different sides of the e shaft.
Which sort of gets me back to my original question. Will the twin dizzy cover bolt onto a 20b and will the dizzy gears line up with the 20b.
I was thinking like you because i like the old school look also, but iv already made up my mind and doing a dry sump cover, FI throttle bodies.
Here's my idea, mod the top of the dizzys with a Subaru Justy 1.2L distributor, 88-90 carbureted, 90-94 EFI........in 1990 it was available in carb or EFI and was the last carbureted car in america.
If you use the EFI distributor could do a waste spark setup or just stick with the carbureted one with points to keep it pure old school and simple....or just mod the cap onto the twin dizz.
I have a Justy cap some place, when i find it i'll get a picture and measure of the diameter to compare it to the twin dizz cap.
Carburetor =/ points. Almost all American cars had electronic ignition by 1974, and I only say "almost" because there's probably something out there that I'm not aware of. I'm not sure where you're going with EFI not having a distributor, either.
The last car sold in the US with points was... guess. I'll give you a hint: It was 1979, and it was Japanese, and there were two sets of everything in the distributor.
Just make things more fun, Bosch D-jetronic (EFI) used points in the distibutor to time/control the fuel injectors.
i changed a set of D jet points its an odd setup. i believe the points open the injectors, and the ecu closes them. it does work, points don't carry current, so they last forever.
i was going to say something about you know points are done when Ford switches, but they probably were electronic by 74 in the cars, trucks probably go a little later. 1974 isn't a coincidence either, 1975 had a catalytic converter, and points + cat = melted stuff
Ford was electronic across-the-board by 1974, started phasing in in the late 60s in high performance models. Better electronic setup than GM's HEI, too, although GM was better for tinkerers because the mechanical advance was at the top of the unit right under the rotor. The HEI was all self-contained but the early modules would crap out at higher engine speeds. Fords had no problem, but then again the Ford "transistorized ignition" was designed to replace dual-breaker distributors, which allowed much longer dwell times for more coil saturation at high RPM. Today you can get GM distributors designed to use Ford caps, for the best of both worlds.
Chrysler had their own setup which was semi-goofy because it still used a ballast resistor instead of feeding the coil 12 volts like electronic ignition SHOULD do, but that way they could keep using the old coils.
Relevant to the thread, you can use Chrysler ignition modules with points to get electronic ignition. Sure you still have points, but since no real current is flowing through them, the points will last just about forever. You should be able to use GM or Ford ignition modules or even RX-7 ignitors, too. A switch is a switch, and all the modules are looking for is a voltage crossover.
Some Carbureted Justys "non" U.S market 1.0L and 1.2L 1984 on up had distributors with points.
Useless car trivia, The Subaru Justy was the last carbureted car available in the U.S. market.
I do not have the twin dizzy set up to engineer the setup im thinking about, i was hoping someone would google a Justy distributor and find a way to put the two together. Use the carbureted distributor and you will have vacuum advance.
Put the Justy distributor on top of the twin dizzy some how so the shaft drives it or just find a way to put the guts of it into the twins. This may take some machining to make either or work.
Hope this clears things up and helps, i think it will work.
It would probably be easier to adapt a Bosch distributor. They were very compact and the same generic distributor head was used in just about everything European. You could easily gt vacuum advance cans to go in either direction. Start with a six cylinder cap and blank off three of the positions.
Yep checking out caps. Was looking at a box of old tractor ignition stuff. A few 3 cylinder tractors around too.
start with something close, make it work.
I think easiest will be original dizzies with adapted efi and some cap.
Even a MSD6a can be triggered with the points. Always blamed points float when the old twin 12a would crap out at high revs??? Who knows now, like to get away from them.
A project to plug away at. My bike needs a little TLC too.
12-27-16, 09:48 PM
