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Thread: GM LT1 to AMC setup

  1. #1
    Electronic Ignition!
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    GM LT1 to AMC setup

    Hi everybody...

    I'm on the ground floor of my injection project..

    I've gotten lots of infomation from other sites, but binderplanet has been very useful thusfar. Yesterday one of the members there recommended me to come here, since you guys were THE PLACE for intel !!

    I have an old school Jeep CJ7 with a V8 360
    It has dual fans that are wired and working correctly..
    Duraspark stock dizzy that now has the large MSD cap and rotor on it, and MSD 6A ignition.

    What I'm trying to do is adapt a GM LT1 injection setup on it.

    I believe, I can handle the mechanical side of things: cutting up the stock LT1 intake and adapting it to a custom made "tunnel" to mate with the carb flange on an edelbrock intake, drilling the intake to accept injectors, building fuel rails, pump, and lines, etc....

    Its the electric side I have questions with. One person suggested using a megasquirt system, another suggested using a 7730 PCM, and that it might work with my duraspark dizzy (not requiring a crank sensor)??? another suggested an OBD1 computer..

    I have a fairly new Centech wiring harness in my Jeep that I'd prefer not to hack up too badly.

    Before I go to the JY and buy something I DONT need, I'd rather get some intel on what I SHOULD get my hands on.

    I guess I'm just looking for a setup that will run the injection system and no other accessories, such as tranny, ABS, fans, turbo, etc...

    thanks in advance for any help or suggestions...
    sincerely,
    brian

  2. #2
    EFI GearHead ! EagleMark's Avatar
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    I saw that poor guy helping out another guy and he got banned for mentioning this site? That's a shame as all the bins and TunerPro files he was looking for are here and was told they don't exist...

    Since you seem to have mechanical end handled I'll try to give you some information on the electronics side of the LT1.

    You can convert an OBDII LT1 to OBDI LT1 with changing the PCM and removing the crank sensor. Plug and play. Some say the OBDII ecm can be reflased to OBDI bin but I have never tried.

    The LT1 PCM is awesome as it is Sequentail Fuel Injection over batch fire, dual heated O2 sensors, Dual knock sensors, sweet tuning XDF for bin file, Sweet ADX for recording data, capable of controlling E trans.

    Problems for conversion to other engines is Cam sensor and the OptiSpark distributor which is the heart of the system. I don't know if the LT1 PCM could be tuned to use a stock type distributor and if it could you may loose SFI. Could do a Hybrid Distributor and machine the OptiuSpark to your AMC base like this:
    http://www.gearhead-efi.com/Fuel-Inj...BI-Conversions

    We'll see what other guys say.

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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  3. #3
    Electronic Ignition!
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    Eaglemark,
    Is there a specific harness you might recommend? Perhaps one that was easier to alter than another? Firebird, camaro, particular year?

    I have a harness that I WAS TOLD was out of a 96 camaro...Turns out NOT TO BE. There was one plug in particular that no one knew what it went to... I was then told it came from an Impala SS... NOPE... I might have figured it out, possibly from a buick roadmaster!! I've been tinkering with it, stripping away wiring that I dont want/need---mainly just as an experiment... Since I only gave the guy $30 for it, its been a good learning experience. Lesson: know what you want to use before buying it!

    If I could find something that wouldnt require that optispark or crank sensor, I'd be happy..

    Do you know anything about using a 7730 to run this, or is is just not compatible with the LT1 setup??

    brian

  4. #4
    Electronic Ignition!
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    Quote Originally Posted by EagleMark View Post
    Problems for conversion to other engines is Cam sensor and the OptiSpark distributor which is the heart of the system. I don't know if the LT1 PCM could be tuned to use a stock type distributor and if it could you may loose SFI. Could do a Hybrid Distributor and machine the OptiuSpark to your AMC base like this:
    http://www.gearhead-efi.com/Fuel-Inj...BI-Conversions

    We'll see what other guys say.
    SWEET!!!
    I just read through the GM dizzy conversion link you sent!!!
    Did YOU do this!!!???
    Nice write-up... thanks for the link..
    brian

  5. #5
    EFI GearHead ! EagleMark's Avatar
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    Quote Originally Posted by jeepboy45 View Post
    Eaglemark,
    Is there a specific harness you might recommend? Perhaps one that was easier to alter than another? Firebird, camaro, particular year?

    I have a harness that I WAS TOLD was out of a 96 camaro...Turns out NOT TO BE. There was one plug in particular that no one knew what it went to... I was then told it came from an Impala SS... NOPE... I might have figured it out, possibly from a Buick roadmaster!! I've been tinkering with it, stripping away wiring that I dont want/need---mainly just as an experiment... Since I only gave the guy $30 for it, its been a good learning experience. Lesson: know what you want to use before buying it!

    If I could find something that wouldn't require that optispark or crank sensor, I'd be happy..

    Do you know anything about using a 7730 to run this, or is is just not compatible with the LT1 setup??

    brian
    They will all run the motor. B body had PCM mounted left front under air filter box. Buick Raodmaster would have some extra connections to Climate control. You could use this to read codes etc... get temps, fan speed, pretty cool feature other guys wire into Impalas. Show me the plug and I may be able to identify it or find it in my manual. I have a 1994 LT1 Roadmaster, lots of fun to blow doors off stuff with a White Woodgrain Grandpas car!

    The 1992 1993 LT1 PCM looks just like the old 1227727 which was an underhood weather proof version of the 1227730 they will all run MPFI, I don't know if any are sequential or if they have dual knock and dual heated O2 etc...

    Quote Originally Posted by jeepboy45 View Post
    SWEET!!!
    I just read through the GM dizzy conversion link you sent!!!
    Did YOU do this!!!???
    Nice write-up... thanks for the link..
    brian
    Yes I did that about 10-12 years ago and have made them for just about any motor made. Pretty slick setup as it has the EFI cap and rotor. If you look inside the cap and rotor you will see the magic GM made of channeling spark so no chance of misfire.

    Have to be very careful with duraspark conversion invented by Custom EFIS years before anyone else claimed to be the inventor. EFI can handle so much spark advance in certain situations it can fire wrong cylinder (read above cap and rotor). Has burned up a few IH engines number 7 cylinder because of firing order. Very good setup though. Just have to be careful with initial spark setting and full advance settings, some guys set reluctor to gain a few degrees which is helpful till reluctor slips on shaft. Others like Jeep or Ford or whatever that came with Duraspark won't skip but can't gain the few degrees. Others set few degrees wrong direction because of distributor rotation. So have to be careful there.

    Using the throttle body from LT1 would be cool! But may find it easier to do what JeepsandGuns did?
    http://www.gearhead-efi.com/Fuel-Inj...Getting-closer...

    One other thing to think of is OBDII software is EXPENSIVE!!! And you'll be getting rid of most of the stuff it was needed for. So your harness will work with work and plug into OBDI LT1 PCM, software and files are cheap. Tuning options are plentiful. But have to build an Optispark Hybrid. Or go down to 1227727-30 ECM for regular distributor. For now anyways I have never seen one done with regular distributor. But Dave runs an LS1 PCM with vortec distributor and a crank sensor he made. So just have to decide if you want simple and easy or go for something unique and cool.

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  6. #6
    Fuel Injected! JeepsAndGuns's Avatar
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    The LT1 system is a good system, but like mentioned above, its not very swap friendly to other engines. The main part being the optispark. Probably the only way would be to make a hybrid distributor out of your stock one and the optispark one, like mentioned above. That would probably be high dollar.
    OBD2 is nice, but also like said, it is very expensive to tune. I personally would stay with OBD1.

    Are you wanting the LT1 injection system because of specific reasons, or are you really simply wanting MPFI? If your really only wanting MPFI, there are far easyer options out there. I personally am getting ready to swap from TBI to MPFI. I am using the 16197427 truck PCM. It is currently a basic normal TBI system, just like on all the late 80's to 95 GM trucks. I have it on my AMC 401 and I am using the stock distributor and pickup coil to trigger it. The 16197427 is specific to the 94-95 model year and is a great and versitle PCM. It can also run MPFI, and thats exactly how I am doing my swap. You can see in the link posted by mark, I have my intake done and am simply waiting on money to buy the last few items I need. The only wiring mods I will have to do is cut off the TBI injector connectors, and connect the MPFI injectors. It will be batch fire, not sequiencial. But All I have read, is there is very little diffrence preformance wise between the two. The rest of the sensors and wiring harness is reused as is. Very minimal wiring. But there are a few programming mods that need done and a mod to some resistors in the pcm too.
    The other option would be to use the TPI ecm, I think 1227730 and/or 1227727 mentioned above. But I am not to up to speed on those ecm's
    79 Jeep Cherokee, AMC 401, T-18 manual trans, hydroboost, 16197427 MPFI system---the toy

    93 Jeep YJ Wrangler, 4.0L, 5 speed, 8.8 rear, homebrew hub conversion and big brakes, hydroboost, 2.5in OME lift, 31x10.50's---the daily driver

    99 Jeep WJ Grand Cherokee limited, 4.0L, auto, 2wd, leather and power everything, 99% stock---the long distance highway ride.

  7. #7
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    Edited: to Eaglemark....
    My dizzy now has the MSD large cap and adapter that lifts it up a bit. Also has the nicer wires to go with it, and MSD 6A ignition. If I do this dizzy conversion, can I keep this setup, or do I need to abandon it? Will the PCM take over functions that the MSD ignition currently does? I guess I dont fully understand how much control the PCM will have over ignition. I had assumed the PCM just sensed the firing of each cylinder and timed the fuel charge to match it-----and not actually "controlled" the ignition.

    sorry for newbie questions... I HATE not knowing or understanding something.

    sincerely,
    brian

    @JeepsAndGuns: thanks for that information.... BTW: what guns?? I shoot competitively

  8. #8
    EFI GearHead ! EagleMark's Avatar
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    You can keep that set up as the MSD 6a has a tach signal that is square wave to send proper signal to ECM to fire injectors. No ECM timing control. Or trigger an external EST module that is usually in EFI small car distributor for timing control. Timing control from ECM is a good thing.

    Really only way to run the LT1 PCM would be hybrid distributor at least. Or crank sensor and some coding in bin, not a simple task.

    Here's a video of what the OptiSpark or ABITS does and why it is so good!

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  9. #9
    Super Moderator Six_Shooter's Avatar
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    The ECMs and PCMs we play with here will control iginition timing as well as fuel and a various other actuators to run the engine.

    I think what needs to happen is to step back for a minute and find out what your goals are, before recommending any specific parts.

    What is it that you're trying to accomplish with the conversion?
    Why have you zoned in on the LT1 parts?

    Any pictures of your dizzy? You may be able to keep it and still use the GM/Delco EFI to run with it.
    The man who says something is impossible, is usually interrupted by the man doing it.

  10. #10
    The OEM AMC distributor (80+) is PERFECT for triggering the GM PCM that JeepsAndGuns mentioned. I have not tried the batch fire MPFI route, but I am using that ECM on a TBI system. It is fantastic and has tons of settings. It's like an ODB-II PCM without the cost or hassle. :D

    I would highly recommend retaining the computer's timing control function. Much better than trying to "re-curve" your distributor. You can keep your MSD at the same time, too!
    Familiar with 1227747 and 16197427 PCMs

  11. #11
    Fuel Injected! JeepsAndGuns's Avatar
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    Quote Originally Posted by jeepboy45 View Post
    Edited: to Eaglemark....
    My dizzy now has the MSD large cap and adapter that lifts it up a bit. Also has the nicer wires to go with it, and MSD 6A ignition. If I do this dizzy conversion, can I keep this setup, or do I need to abandon it? Will the PCM take over functions that the MSD ignition currently does? I guess I dont fully understand how much control the PCM will have over ignition. I had assumed the PCM just sensed the firing of each cylinder and timed the fuel charge to match it-----and not actually "controlled" the ignition.
    Not knowing anything about the msd ignitioin, but if the pickup coil in the distributor is like the stock one, you should be able to use it to trigger the GM system. I know the stock amc motocraft distributor works perfectly fine. I am using my stock dist. You will remove the msd ignition module and use only the distributor from the stock ignition system. The GM ecm/pcm takes over all timing controll, you simply program in what you want for timing. You will need to lock out the mechanical advance in the distributor (easy to do) and unhook and leave un hooked the vaccume advance.
    79 Jeep Cherokee, AMC 401, T-18 manual trans, hydroboost, 16197427 MPFI system---the toy

    93 Jeep YJ Wrangler, 4.0L, 5 speed, 8.8 rear, homebrew hub conversion and big brakes, hydroboost, 2.5in OME lift, 31x10.50's---the daily driver

    99 Jeep WJ Grand Cherokee limited, 4.0L, auto, 2wd, leather and power everything, 99% stock---the long distance highway ride.

  12. #12
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    @JeepsAndGuns:

    are you saying I need to go back to the factory brain unit? or does the ECM take the place ANY / ALL ignition control?
    (both factory brain, or MSD)

    DAMN!! I hope not... I just got finished getting rid of 2 miles of wiring associated with it, and rewiring to use the MSD for a much better ignition...

    You said you use your stock motorcraft dizzy....... is your dizzy MODIFIED to be a hybrid combination, with GM components inside?

    That would be my luck, I would do this upgrade (teamrush upgrade) and then 2 months later, have to UNWIRE the darn thing to go backwards!!! i hope not...

  13. #13
    Super Moderator Six_Shooter's Avatar
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    The MSD ignition can be retained, it may just get triggered differently than you might be thinking now.

    Most of the time the points trigger will get used to trigger the MSD box, this allows the ECM to control timing with the benefits of the MSD ignition.

    Laying out your goals for this engine will greatly help us give you a clear plan on what to use and how to connect it.
    The man who says something is impossible, is usually interrupted by the man doing it.

  14. #14
    EFI GearHead ! EagleMark's Avatar
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    Quote Originally Posted by Six_Shooter View Post
    Laying out your goals for this engine will greatly help us give you a clear plan on what to use and how to connect it.
    I agree. Someone sent him here for information as what he was getting elsewhere was mis information. I don't think he knows yet what his goals are other than EFI, he got a LT1 harness PCM and parts which is going to be a lot harder to do a conversion with than say 1227730. So it's been more of an information learning experience for him till this point. He may have enough information now to decide on what kind of system to build using parts he has an adapting others.

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  15. #15
    I can't help you with the LT1 PCM or harness. I've never played with one. However, I have used a 1227747 ECM and have since switched it over to the 16197427 PCM. Both of those computers will use the STOCK AMC distributor for ignition and timing control. As mentioned, you will have to lock out the mechanical advance and simply disconnect the vacuum advance. There are a bunch of writeups all over on how to use the '7747 ECM. It's easy to modify and simple to use.

    The 16197427 PCM has a huge increase in the # of parameters that can be changed and adjusted. But if this is your first time programming a TBI system, it can be pretty intimidating. One of the biggest advantages (IMHO) of the '7427 PCM is that it has a faster data output and larger tables for spark and fuel.

    With regards to keeping your MSD: The distributor is connected to the PCM. The PCM outputs a signal to the MSD. The MSD then sends spark to the engine (via the distributor, of course). Another advantage of the computer controlling timing is that you no longer need the Duraspark system.

    BTW, this is all assuming you don't have something like a Prestolite ignition (points).
    Familiar with 1227747 and 16197427 PCMs

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