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Thread: Electronic Ignition Conversion & Laying the groundwork for EFI

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    Electronic Ignition Conversion & Laying the groundwork for EFI

    First, a preface: I am not an airboat builder. I purchased a 4A084 engine for another purpose but this seems to be the remaining active online repository for 4A084 engine. I figured if I shared my project with you all it might help someone out. So, on to the project.

    Recently I purchased a Hercules 4A084-3 in an unknown condition for a song. I was finally able to get it running yesterday and after I plumbed up a makeshift muffler to get a listen for mechanical noise I discovered the engine is nearly silent mechanically. Compression is 130 across all 4 cylinders and although the Tillotson carb is dealing me fits, the engine purrs like a kitten when the mixture is right. Probably has something to do with the float needle seat being as hard as a rock and won't seal. That MIGHT explain the carbon buildup on the freshly-cleaned spark plugs. Anyway, I digress.

    The points are in bad shape. I mean very, very bad shape. Coming from a small engine repair background I have come to loathe points-condenser-magneto ignition systems (Especially the ones behind the aluminum flywheel seized onto the steel crankshaft) and since the points are already needing to be replaced, what better time to convert to something a bit more modern? My plan is to initially retrofit the engine with different plugs and a COP ignition system being run by a microcontroller. The COP should help mitigate EMI vs plug wires and remote coil packs. Phase 2 is to add port fuel injection. Here's the plan for parts on Phase 1:

    Coils: Toyota 1ZZ's, p/n 90919-02239 $40/4 at the junkyard
    Controller: Speeduino v3 - $100 (Self-asssembled, I already have a couple Arduino Megas laying around collecting dust)
    Plus wiring connectors and misc odds and ends that usually end up doubling the cost

    I will have to make a trigger wheel for the crank and I'm not entirely sure how I want to go about it. Since the front of the crankshaft is not keyed on my engine and if for some reason the pulley is removed the trigger wheel-piston timing will be changed requiring a whole bunch of work to re-time it all again. No bueno. So that leaves two options. Either placing a trigger wheel on the back end, OR machining a plate that bolts in place of the magneto and sliding a shaft through a pair of bearings, slipping on the magneto gear, and having that drive a 36-1 trigger wheel right where the magneto currently sits. Since there will be slight variations due to geartrain slop I am not 100% sold on this idea, either. Or I could put the wheel on, tighten the nut, and pray to God I never have to remove it and re-time it again.

    Right now I am still in the cleanup and gasket replacement stage. She holds oil well enough but I would rather do it now while parts are still readily available vs 10 years from now when gaskets and seals are having to be heisted from a museum somewhere. Thoughts on how insane I am for going this route?

    Future plans for EFI should be somewhat straightforward. Welding injector bungs into the existing intake tubes, adding a fuel pump and regulator, fabbing a fuel rail, and using the existing carb as a throttle body if I don't buy an el-cheapo 34mm throttle body to replace the near-worthless carb. Oh, and an O2 sensor. Can't forget that. Maybe put in 3 or 4 upstream and downstream of a catalytic converter to make the granola-munchers happy.

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    Re: Electronic Ignition Conversion & Laying the groundwork for EFI

    Welcome to the site......A few of us were discussing possibly making a keyway channel for the front pulley...That would keep it indexed so you could add timing marks as well as adding any crank triggered accessories like what you're contemplating..
    Electronic ignition would be a great step up into the 21st century there's been quite a few members that experienced magneto failures...
    The COP arrangement would be a good thing I'm wondering just how the heat transfer is going to interact with it...Cylinder head temps are close to 500* in that area...
    It will be interesting to see just how the port fuel injection will affect the operating temps of these engines hopefully it will drop the temps enough to give some room for additional modifications {like camshaft profiles and higher compression down the road}...
    Anyhow I'm sure everyone running one of these engines will be looking forward to your project for the potential gains to be had....

    Aluminum .120 14' X 76" hull
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    Re: Electronic Ignition Conversion & Laying the groundwork for EFI

    it sounds like you have a little knowledge about all of this.
    as far as putting a keyway on the front pulley and shaft, it isn't to hard, that was one of the mods that I did a couple of years ago, it was kind of a rough method, with the tooling and knowledge that i have now, it would be looking a lot better, but that is how we learn. here is the link
    http://miniairboatassoc.com/forum/sh...-the-084-motor
    down the road if i ever dissemble the crank, i may use a woodruff key cutter and do it correctly the next time. ( if you look at all the crank shafts off the 2a042 motors they all have a cut out for woodruff key on them. )
    i haven't got all my projects finalize on this motor, but i do like having timing marks front pulley
    it would be fun to see how & what your plans are, in installing the EFI & electronic ignition.
    i have looked at the this system, http://www.sdsefi.com/ where it is more of a plug and play, and all you need to do is figure out fuel mapping. but that is just a little chunk of change.
    there are some other programmable controllers out there for an EFI system, just needing the time to read up and learn what would work.
    i look forward to see how your project goes and where it takes you. good luck, and keep us informed.

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    Re: Electronic Ignition Conversion & Laying the groundwork for EFI

    It has been a good morning, i googled the Speeduino 03. downloaded the manual, there is a lot of good information there, and it is almost in layman's terms. that i can understand,
    in my searches before i have came across the Megasquirt controllers, but they always intimidated me, where i would just see the bare boards and never did take the time to look at any forums and dig any deeper, but after reading the manual, i can see this may be a start for another project. llife is fun

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    Re: Electronic Ignition Conversion & Laying the groundwork for EFI

    the fuel injection would be something to think about if it was affordable. and the electronic ignition would solve all the problems i had with the magneto. keep going and let us know what you come up with.
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    Re: Electronic Ignition Conversion & Laying the groundwork for EFI

    A little progress made today. The coils are ordered, along with the wire connectors, Autolite 386 spark plugs, and the Speeduino board. Right now the engine is disassembled for cleaning and inspection. The bores and pistons, rings, valves, and bearing surfaces are all within factory-installed specs. The bores still have the cross hatch from the honing which is a welcome sign. While attempting to remove the fittings for the oil lines one of them twisted off inside the block. A couple hours and many creative strings of profanity later, I was able to chase the threads with a tap and we are back in business. Everything has been run through the ultrasonic cleaner and now I wait for my gasket and seal kits to come from Saturn Surplus. Anxious to get the old girl put back together.

    I am still sorting through the Speeduino BOM and finding part replacements for the obsolete numbers on Digikey. If this ends well and people want to try their hand at doing this retrofit I may assemble a kit for you guys with a custom PCB and a proper ECM case. The 48-pin ECM cases on AliExpress look like they would work nicely, except that the details on board size are a crap shoot. Might be a trial-and-error process to get a correct case size for the necessary board size.

    In looking at the front pulley I am certain I can dremel-out a keyway on the crank to match the pulley. To make a trigger ring I will try bolting it to the back of the rope pulley. With a hall sensor it should work pretty well.

    Next week I hope to get a couple days when work let's me go home and the wife's computer doesn't require data recovery. Updates to come.

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    Re: Electronic Ignition Conversion & Laying the groundwork for EFI

    Here are the specs on the coils:

    1. Part Number: UF247
    2. Quantity: 4 Pcs / Set
    3. Fitment:
    2000 - 2002 Chevrolet Prizm 1.8L L4
    2003 - 2008 Pontiac Vibe Not Fit Gt 1.8L L4
    2000 - 2005 Toyota Celica Gt Not Fit Gts 1.8L L4
    2000 - 2008 Toyota Corolla 1.8L L4
    2003 - 2008 Toyota Matrix 1.8L L4
    2000 - 2005 Toyota Mr2 Spyder 1.8L L4

    These fit the Toyota 1zz series of engines. Since they are a "smart" coil they won't require an ignitor circuit. Direct control by the ECM makes things simple.

    The heat issue got me thinking. Initially I wasn't going to put sheet metal around the engine, but in the interest of keeping the coils cool I may duct the airflow over the heads and screw the coils to that ducting. That should put the coils outside the hot zone. Keyword being "should".
    Last edited by armorer243; 04-27-2018 at 08:58 PM.

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    Re: Electronic Ignition Conversion & Laying the groundwork for EFI

    Those oil line fittings always give me a bad feeling when trying to remove them from the block for the reasons you've just encountered...I thought for sure I was going to snap one but got lucky and it broke loose...
    Glad to hear the pistons/jugs are in good shape that should make a good engine for the tests...For the price of the gasket kit it wouldn't make sense not to get it done before your trial runs...
    Thanks for listing the application of the coils that should make it easier to find them when needed..
    I don't think it would take much to shield the coils from the radiant heat with any type of air movement over the heads...

    Aluminum .120 14' X 76" hull
    Teledyne 4a084-4 engine
    Circle S 1.69:1 reduction
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    Re: Electronic Ignition Conversion & Laying the groundwork for EFI

    the only advise i can give you on brouching the pulley for the keyway, is double check your line before you start cutting it. i clamped straight edges on both sides of the pulley. thinking i could keep the line straight, but after i was done i found out the straight edges were just a couple of degrees off, from each other.
    from the pictures that i posted, i had cut the groove in the pullley first, then using a chalk line to mark the shaft to correspond to the groove, it was then that i noticed how far out of square my cut was, i cut the key way in the shaft at the same angle. so it would match and not bind up, as the pulley was slid on.
    if i would have taken the time to install the pulley on my friends lathe, the slot in the pulley would have ran true. and things would have looked a lot more professional. but we learn from our mistakes.
    so I hope you take a little more time, and yours turns out better than mine.

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    Junior Member Bart's Avatar
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    Re: Electronic Ignition Conversion & Laying the groundwork for EFI

    this page has a couple of pictures of how one installed a hall sensor to the front pulley
    http://miniairboatassoc.com/forum/sh...Problems/page3

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    Re: Electronic Ignition Conversion & Laying the groundwork for EFI

    Quote Originally Posted by Bart View Post
    the only advise i can give you on brouching the pulley for the keyway, is double check your line before you start cutting it. i clamped straight edges on both sides of the pulley. thinking i could keep the line straight, but after i was done i found out the straight edges were just a couple of degrees off, from each other.
    from the pictures that i posted, i had cut the groove in the pullley first, then using a chalk line to mark the shaft to correspond to the groove, it was then that i noticed how far out of square my cut was, i cut the key way in the shaft at the same angle. so it would match and not bind up, as the pulley was slid on.
    if i would have taken the time to install the pulley on my friends lathe, the slot in the pulley would have ran true. and things would have looked a lot more professional. but we learn from our mistakes.
    so I hope you take a little more time, and yours turns out better than mine.
    Thanks Bart, I appreciate the help. Luckily I won't have to broach the pulley, the manufacturer was kind enough to do it for me. All I have to do is cut they keyway on the crank.

    A little progress made today, finally got it buttoned back up. For the most part anyway. The spark plugs showed up and I threw those in.







    Waiting on the board, coils, starter, and all the other wiring gadgetry to arrive. I took a look at mounting the trigger wheel to the front of the rope pulley but I am not entirely sold on that arrangement. If I don't end up machining a new pulley for the front end I will try fastening the trigger wheel to the engine-side of the rope pulley to keep things more compact.

    I was also running some numbers on injector pulse width and if I run one 90cc injector per cylinder at 37psi I will be really low on the pulse width at idle. That is running fully sequential EFI with trigger wheels on both the crank and the cam. For the cam, I think I will machine a couple plates to bolt into the governor and magneto spots. These plates would have plain bearings and a shaft that runs through, with the magneto gear returned to its position on the shaft. This would give me a stub out for a second encoder wheel for the ECU to know whether it is TDC on the power or exhaust stroke. Should only take a day of machine work on the lathe.



    Full image files will be located here: http://digitaldownpour.org/4A084
    Last edited by armorer243; 05-01-2018 at 08:04 PM.

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    Re: Electronic Ignition Conversion & Laying the groundwork for EFI

    you never said what you were going to use this engine for but the looks of it you are going to use the factory bell housing and flywheel. it's a little late but the bmw starter series 3 and 5 are the same tooth pattern as the factory flywheel and run less than 50 bucks on ebay. just saying.
    4a084
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    Re: Electronic Ignition Conversion & Laying the groundwork for EFI

    Quote Originally Posted by bgmcl60 View Post
    you never said what you were going to use this engine for but the looks of it you are going to use the factory bell housing and flywheel. it's a little late but the bmw starter series 3 and 5 are the same tooth pattern as the factory flywheel and run less than 50 bucks on ebay. just saying.
    Yep, a BMW starter is what I have coming. I am going to try reusing the factory housing and flywheel and fabricate up some new tin ducting. But since this will be going on a snowblower built from the ground up the winter temps should keep the engine cool.

    Probably a dumb idea, but I was looking for a 2L car engine up til now and this, although slightly less power, will do well mostly because I don't have to fart around with a radiator and everything that goes with it. Hopefully my budget-minded ignition retrofit can help the airboat guys out.

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    Saturn has a 1" shaft that bolts to the rear flywheel to add a pulley if you are going belt drive for blower.

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    4a084
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    weber 32/36
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    Re: Electronic Ignition Conversion & Laying the groundwork for EFI

    Quote Originally Posted by bgmcl60 View Post
    Saturn has a 1" shaft that bolts to the rear flywheel to add a pulley if you are going belt drive for blower.

    Sent from my SM-G935VC using Tapatalk
    I may have to look into that. I have a lathe but sometimes it doesn't make sense to spend an hour machining something it it can be purchased for $5.

    So after doing some reading I have devised a plan. The Speeduino board and code can either fire coils on each revolution of the crankshaft (2 sparks per cycle or 'wasted spark') or sequentially, one spark per 2 revolutions of the crank, only at TDC. Here is how to do each.

    Batch (Wasted spark) : a single trigger wheel on the crankshaft, none on the cam. The ECU only knows that the crank has rotated, but has no way of knowing which stroke the crank is on, power or intake. As such, it sparks twice.

    Sequential : Either two wheels, one on the crank and one on the cam. OR a single cam-speed wheel with a missing tooth. There is a drawback to this approach, as the accuracy is only as good as the geartrain slop. But if it was good enough for it to run well before, it should run just as well or maybe better because of slightly increased accuracy from more trigger points.

    I am going to run a single cam wheel. In the next few days I am going to draft up a set of plans and make bearing caps for the governor and magneto holes, passing a shaft through them which will be turned by the magneto gear. It will be a plain brass bushing with pressure lubrication from what used to be the governor oil line.

    My reasons are as follows: No pulley modifications. No crankshaft keyway cutting. No risk of the pulley magnets giving false readings to the hall sensor as a result of the close proximity. No loss of the magneto (although a mini alternator is on the list of things to buy). It just seems like a rather elegant solution that can be easily bolted in place of the governor and magneto assemblies. Pics to come when I get back out to the garage.

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    Re: Electronic Ignition Conversion & Laying the groundwork for EFI

    crap..... I just had an epiphany. I can't run a trigger wheel from the magneto gear. It turns at a different speed than the camshaft.

    There goes that idea. Since there isn't any room inside the timing confer to attach anything to the cam gar directly I am boned. Gotta go with wasted spark and a single trigger wheel on the crankshaft.

    Back to the drawing board on what to do with the rope pulley.

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    What is wrong with waste spark? My van uses it and a lot of other engines.

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    4a084
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    Re: Electronic Ignition Conversion & Laying the groundwork for EFI

    Quote Originally Posted by bgmcl60 View Post
    What is wrong with waste spark? My van uses it and a lot of other engines.

    Sent from my SM-G935VC using Tapatalk
    For spark, absolutely nothing wrong with waste spark which is how I am going to run it initially.

    My goal was to port EFI as well. The problem I am calculating is the injector sizing being an issue if they aren't sequential. The smallest injectors I can find are 90cc and at 1 per cylinder, firing twice per cycle at idle, the injector pulse duration is going to be so short I am unsure it will be able to idle. If it was sequential with a single shot of fuel per cycle instead of two it would work fine. If I have to do a throttle body injection I can, but it wasn't how I wanted to go about it.

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    Re: Electronic Ignition Conversion & Laying the groundwork for EFI

    A wee bit of progress to report today.

    I made a simple 4-tooth trigger wheel and attached it to the engine side of the rope pulley. The magnets wreaked havok with the hall effect sensor I am going to use so that put the kabosh on that. Sooooo.....

    A few hours of work with the 1948 South Bend 9a lathe and I have the pulley replacement. 2.5" 1/4-20 bolt circle and 2" shoulders for pilot mounting the trigger wheel on the engine side, the same is mirrored on the outside for a belt pulley to bolt to, running the future alternator.

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    Now to make the trigger wheel. Hope to find another plate of steel laying around here somewhere. If not I will scrounge some up somewhere. More pics forthcoming.

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    Re: Electronic Ignition Conversion & Laying the groundwork for EFI

    Now that the coils have showed up I am....... Disappointed...... I think the use of the Toyota coils might be the wrong way to go now that I see them. Here is why:

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    They stick out almost 3" beyond the valve cover and that is without the wiring connectors. :-/ Add in another 2" for those and we are 5" on either side. Adding 10" of width to the engine? No bueno. So I am going to go another way. I think I will fabri-cobble some short plug wires and mount the coils beside their respective cylinders and call it good enough. If I had it to do over again, I would just get some GM LS2, LS3, or LS7 coils and run short wires to begin with. I may still do that, a field trip to the junkyard may be in order.

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