crank trigger ignition questions

[Beck]

I am trying to put a crank triggered ignition together for my latest tractor project. Actually I was thinking about cam triggering it.   This is just a single cylinder motor. Here is a link to a sight that I have been refereing to http://members.aol.com/pullingtractor/ignition.htm.
The electronics are taken care of by using a Mopar setup that was in use for a long time on all the Mopars except the "lean burn" models. I am having a problem with the Hall effect pickup. I want to run something really small (hidden). The sight refers to a couple of GM crank trigger pickups but they are all bigger than I want. I have seen information on some tiny pickups but have yet to find one. The electronic store closed tonight before I could make it there. Radio Shack has one on their web sight but it is no longer available. Some of the model airplane guys have been converting their little 4 stroke motors to ignition and their setups look pretty neat, but won't power an automotive coil.
Will using the cam for the pickup point cause any problem? I know the plug will just fire on the compression stroke if it is cam triggered. If it was crank triggered it would fire on the exhaust stroke also. Will it affect the dwell angle? Does the electronics change the dwell dependent on rpm? I guess the dwell is electronically set? One of the model engine sights had a setup that didn't use electronics. They used a row of magnets to keep the Hall effect sensor on to establish the dwell angle. Then when the last magnet passed the sensor the plug fired. The next big question is why do some of the sensors I see use magnets to trigger them and others just a piece of steel. The GM sensors have a magnet mounted on the end of them. They don't use a magnet to trigger them. The ones I see for model use don't have the magnet on the sensors but use the magnet to trigger them. All of the information I have seen have a non ferrous disk to mount the magnet or steel pin. If using a steel pin for the indicator why couldn't it just be a piece that sticks out from a steel disk. I realize the rest of the disk would have to be far enough away so it wouldn't trigger the sensor. I am thinking about putting a screw into the cam gear. As long as I let plenty of clearance between the pickup and the gear will that work?
I think I am in over my head! :?:

[unklian]

We ran a crank trigger on a 2 liter Hart motor in SCCA Can Am back in the mid '80s.It came with a crank trigger,that worked with a small distributor cap,crummy electronic box,and external coil.
It ran MUCH better when we put an Accell Super Coil
and MSD box on it.
The more American parts we put on it,the better it ran.
Eventually,we were buying semi finished pistons from Germany,and machining our own domes to get more compression than the factory parts.
But I digress.

It had a steel disc on the front of the crank,maybe 2" in diameter,with a 1" + long finger coming off each side.The plate was around 1/4" thick,and the fingers were no more than 1/2" wide.It proved to be a vulnerable design,and I had to make a new one,so those dimensions are close.

The sensor has a certain range that it can "see".
Anything ferrous in that range will create a signal,that's why some units run a large non-ferrous disc with steel pins or magnets.

What kind of single cylinder motor is this ?

[SKR8PN]

I am trying to put a crank triggered ignition together for my latest tractor project. Actually I was thinking about cam triggering it.   This is just a single cylinder motor. Here is a link to a sight that I have been refereing to http://members.aol.com/pullingtractor/ignition.htm.
The electronics are taken care of by using a Mopar setup that was in use for a long time on all the Mopars except the "lean burn" models. I am having a problem with the Hall effect pickup. I want to run something really small (hidden). The sight refers to a couple of GM crank trigger pickups but they are all bigger than I want. I have seen information on some tiny pickups but have yet to find one. The electronic store closed tonight before I could make it there. Radio Shack has one on their web sight but it is no longer available. Some of the model airplane guys have been converting their little 4 stroke motors to ignition and their setups look pretty neat, but won't power an automotive coil.
Will using the cam for the pickup point cause any problem? I know the plug will just fire on the compression stroke if it is cam triggered. If it was crank triggered it would fire on the exhaust stroke also. Will it affect the dwell angle? Does the electronics change the dwell dependent on rpm? I guess the dwell is electronically set? One of the model engine sights had a setup that didn't use electronics. They used a row of magnets to keep the Hall effect sensor on to establish the dwell angle. Then when the last magnet passed the sensor the plug fired. The next big question is why do some of the sensors I see use magnets to trigger them and others just a piece of steel. The GM sensors have a magnet mounted on the end of them. They don't use a magnet to trigger them. The ones I see for model use don't have the magnet on the sensors but use the magnet to trigger them. All of the information I have seen have a non ferrous disk to mount the magnet or steel pin. If using a steel pin for the indicator why couldn't it just be a piece that sticks out from a steel disk. I realize the rest of the disk would have to be far enough away so it wouldn't trigger the sensor. I am thinking about putting a screw into the cam gear. As long as I let plenty of clearance between the pickup and the gear will that work?
I think I am in over my head! :?:

The old MOPAR Electronic ignition box,controlled the dwell,so you don't need to worry about that part,as long as the ignition curve that is programmed into the box is close to what you need. Also,the trigger does NOT have to control voltage to the coil,all it does is trigger the electronic box to fire the coil.  Depending on what engine you are talking about,can you run the trigger INSIDE the block to hide it?  As far as the different types of sensors you are talking about,they all work basically the same. Some use a disc with slots in it,with the magnet in the sensor,and others use what is a called a "flying magnet" that passes over steel trigger.If the sensor has 3 wires,it uses a 5 volt supply to AMPLIFY the signal(you won't need that) For your application,I would think a plain old mopar distributor taken apart and modified to fit your application, would work OK. If you are going to use the MOPAR box,I would stay with a CRANK triggered setup . The cam triggered deal will proly be a bit more difficult to set up simply because of lack of space near the camshaft........What ARE you working on???

[Beck]

I was intentionally a little fuzzy about the motor type. I was trying to keep the web search engines from finding this. I didn't want to share all of the knowledge from you guys with the rest of the tractor world.
I am building a Kohler single cyl garden tractor motor. I have a 10 and 12 hp sitting here that I am messing with to try to figure this out, but when it is all finished it will be on a 16 hp motor.
If I put the timing wheel on the crank it will have to be exposed since there is no room in the block to hide it. If I put the timing wheel on the cam there seems to be room in the block. In fact there is a cutout in the block that the cam gear rotates in. There is just a small bolt on cover that encloses the cutout. That is where I wanted to mount the pickup so I could access it to adjust the timing. I will try to post a picture when I get home from work tonight.

[Beck]

The old MOPAR Electronic ignition box,controlled the dwell,so you don't need to worry about that part,as long as the ignition curve that is programmed into the box is close to what you need. Also,the trigger does NOT have to control voltage to the coil,all it does is trigger the electronic box to fire the coil.  Depending on what engine you are talking about,can you run the trigger INSIDE the block to hide it?  As far as the different types of sensors you are talking about,they all work basically the same. Some use a disc with slots in it,with the magnet in the sensor,and others use what is a called a "flying magnet" that passes over steel trigger.If the sensor has 3 wires,it uses a 5 volt supply to AMPLIFY the signal(you won't need that) For your application,I would think a plain old mopar distributor taken apart and modified to fit your application, would work OK. If you are going to use the MOPAR box,I would stay with a CRANK triggered setup . The cam triggered deal will proly be a bit more difficult to set up simply because of lack of space near the camshaft........What ARE you working on???

I believe the Mopar system had the trigger mechanism inside the cap of the distributor. That is where the advance was added into the system. The electronics doesn't have a curve map built into it.  :?:
I realized all the sensor had to trigger was the power transistor that is in the electronics box, not the coil. The small setups like the model guys use don't have a big enough power transistor to feed the auto style coils.
You solved one of my mysteries about the 5v feed to the pickup. All of the information I have seen on the tiny hall effect pickups show a power feed to them. I would prefer not to use the flying magnet since that would require a non ferrous mounting, but all of the tiny (chip style) pickups seem to require the magnet. It's much easier for me to work with steel.

[sirstude]

We had a seminar this weekend on wiring, and one of the guys mentioned that radio shack has a tiny hall effect switch, like a quarter inch square, that can be triggered by a magnet.  He was using them to open the doors on a car.  He just used them to trigger a relay, that carried the amperage for the door opener.  How about using that kind of a setup relay's and all to trigger the ignition?

Doug

[Beck]

We had a seminar this weekend on wiring, and one of the guys mentioned that radio shack has a tiny hall effect switch, like a quarter inch square, that can be triggered by a magnet.  He was using them to open the doors on a car.  He just used them to trigger a relay, that carried the amperage for the door opener.  How about using that kind of a setup relay's and all to trigger the ignition?

Doug

Radio Shack told me last night that they no longer carry the hall effect sensor. It is still on their web sight but the sales rep from Radio Shack supply wholesaler said it wasn't available.
Tom

[SKR8PN]

I assume your using this for pullin' What kind of RPM's will you be turning?How much compression and is it an aluminum head?  Would you really even need any advance or retard on the ignition? I was thinking of using the pickup assy out of the MOPAR distributor and mounting it WITHOUT any advance/retard capabilities,and just run the box to fire the coil.

[Stakebed]

Does the motor have any kind of advance built into the original ignition? If not you should be able to trigger it off the cam, distributors run at cam speed. getting the timing right would be the hard part.  the mopar ignition pickup should work with a metal tab to trigger it,as the magnetic part is in the pickup coil. I'm not sure if I can but I will try to post a picture.
 well that didn't work, the trigger points on the chrysler are about 1/16" wide. The gap specs vary if you look in motor manuals but if I remember right they run from about .008 - .014 inch. Themain thing is to have enough gap so you don't hit the trigger on the coil. I have converted about 20 engines to the chrysler system, mostly old 4 0r six cyl farm tractors and one flathead in a 40 coupe for a friend, and have had good results. You would need the pickup from the dist, the control box, the ballast resistor and the coil. Also whatever you come up with for a trigger. Most 70's motor or chilton's manuals should have a wiring diagram.
  One other thing, the control boxes come in 4 or 5 pin styles. The 5 pin seems to be more common, and uses a double ballast resistor. The 4 pin uses a single ballast resistor as the other resistor is built into the box. If you have the wiring for the 5 pin with the dual resistor either box will work but you can't run the 5 pin box if its wired for the single resistor.
  Hope this helps.

[unklian]

Have you got a pic of this Koh*** motor  in race trim ?
Gas or Alky ?
2 stroke,4 stroke ?
Flat head or OHV ?

How tight are the rules ? :?:

What is the stock ignition system ?
Are dual plug heads legal ?

Could you hide a crank trigger behind the flywheel ?

And could you hide a MSD box under the seat ?
Or inside some Dummy Ballast ?
Or under the floor ?

Putting sensors inside the motor makes it tough to set the timing.

[Beck]

Have you got a pic of this Koh*** motor  in race trim ?
Gas or Alky ?
2 stroke,4 stroke ?
Flat head or OHV ?

How tight are the rules ? :?:

What is the stock ignition system ?
Are dual plug heads legal ?

Could you hide a crank trigger behind the flywheel ?

And could you hide a MSD box under the seat ?
Or inside some Dummy Ballast ?
Or under the floor ?

Putting sensors inside the motor makes it tough to set the timing.

I have been trying to post some pics for the last hour. No luck. The only thing I have in the garage is a long block and a parts motor. I am still trying to fab up some parts. The motor will look like a stock garden tractor motor. It may be missing a little of the cooling baffle sheet metal. These motors are 4 stroke flatheads. The rules are very tight. Not much is allowed. The only modification that is allowed in the local club in the stock class is porting. Most guys do a 3 angle valve job. The stock ignition is a set of points triggered from a pin off the camshaft. This feeds a standard auto style coil. There is a full charging system for the 12v battery, but most guys disable it so there isn't any power lost in the charging system. No dual plug heads are allowed in this class. There are several places to hide things. The MSD box isn't a great help for this engine. Suprisingly the Mopar electronic ignition is the choice of the guys playing with this type of ignition. There would be room for a tiny pickup behind the flywheel. There would be room for a tiny pickup under the cam gear cover also. The rules vary from club to club. There are many different classes. This tractor will be in the mildest class. There is no power advantage to the electronic ignition. It just gives super reliability. The points are prone to dirt and vibration. With points tiiming is on the checklist before every event. As I said the rules are tight but I have never seen a tractor torn down at a local event. When the big boys (National Quarter Scale) pull the top 5 tractors in each class are torn down. This tractor isn't up to their caliber. Their rules allow a lot of modifications and they make about 80hp from a 16hp sized motor. Mine will be a 16hp motor and make 18hp if it's lucky.

[Beck]

Does the motor have any kind of advance built into the original ignition? If not you should be able to trigger it off the cam, distributors run at cam speed. getting the timing right would be the hard part.  the mopar ignition pickup should work with a metal tab to trigger it,as the magnetic part is in the pickup coil. I'm not sure if I can but I will try to post a picture.
 well that didn't work, the trigger points on the chrysler are about 1/16" wide. The gap specs vary if you look in motor manuals but if I remember right they run from about .008 - .014 inch. Themain thing is to have enough gap so you don't hit the trigger on the coil. I have converted about 20 engines to the chrysler system, mostly old 4 0r six cyl farm tractors and one flathead in a 40 coupe for a friend, and have had good results. You would need the pickup from the dist, the control box, the ballast resistor and the coil. Also whatever you come up with for a trigger. Most 70's motor or chilton's manuals should have a wiring diagram.
  One other thing, the control boxes come in 4 or 5 pin styles. The 5 pin seems to be more common, and uses a double ballast resistor. The 4 pin uses a single ballast resistor as the other resistor is built into the box. If you have the wiring for the 5 pin with the dual resistor either box will work but you can't run the 5 pin box if its wired for the single resistor.
  Hope this helps.

The motor does have advance built into it. It isn't adjusted by rpm. It is like the initial advance on the old distributors. It is all in all the time. There is an automatic compression release built into the cam to help starting.
I'm told the distributor pickups are not the ones to use. Why I don't know. I assume since I only have one cylinder to trigger it isn't worth the work of removing the pickup from the distributor.
On the wiring diagrams I have seen drawn up for use on single cylinder motors there are never 2 ballast resistors used. The E pin on the Mopar box isn't connected to anything. I don't know what it was used for on the original application. I've read there isn't a ballast resistor in any of the boxes. The reason for not putting them in the box is the amount of heat they generate. The heat would destroy the other electronic parts.

Beck

[unklian]

On some of these deals,people run the same stuff as everyone else,
just because that's what everyone else runs.
Monkey see,Monkey do.

Performance advantages are found in taking the Bull by the horns,
and trying new things.

We were running a shoe string operation in Can Am,but the guys with the lastest trick motors from England,Germany,and Switzerland couldn't stay in our draft going up the back straight at Mosport.

We had better:
fuel injection(Kinsler modified metering unit),
fuel(10-15% Tolulene),SShhhhhhhhhh !!!  
ignition(MSD box with Accell Super Coil),
plug wires(Moroso Blue Max),
more compression(custom machined pistons),
more timing(factory recomended 34 degrees,we ran 40+)
They all figured we had a 2.5 liter motor,but would never put up the money for a tear down.Too bad,because they would have lost.

When we built the single seater Formula 4,everyone else ran drum brakes.
Why?because...everyone else ran drum brakes.Same thing with the ugly suspension and bulky bodywork.Follow the crowd ? Don't think so.

We built the narrowest body anyone had ever seen,the one off steering wheel was 8" in diameter to fit inside the body.Inboard pushrod suspension,disc brakes with custom billet aluminum calipers before anyone had heard of such a thing.(This was 20 years ago)Ran at the front right out of the box. All the cars built since have follwed suit.

It would be interesting to compare ignitions,and exhaust pipes,on a dyno.