GM LT1 to AMC setup

[jeepboy45]

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

[EagleMark]

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-Injection/showthread.php?21-Building-a-GM-EFI-Small-Cap-Distributor-for-TBI-Conversions

We'll see what other guys say.

[jeepboy45]

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

[jeepboy45]

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-Injection/showthread.php?21-Building-a-GM-EFI-Small-Cap-Distributor-for-TBI-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

[EagleMark]

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??

brianThey 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...


SWEET!!!
I just read through the GM dizzy conversion link you sent!!!
Did YOU do this!!!???
Nice write-up... thanks for the link..
brianYes 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-Injection/showthread.php?534-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.

[JeepsAndGuns]

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

[jeepboy45]

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

[EagleMark]

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!

http://www.youtube.com/watch?v=lFCjaz6zHfc

[Six_Shooter]

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.

[FSJ Guy]

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!

[JeepsAndGuns]

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.

[jeepboy45]

@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...

[Six_Shooter]

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.

[EagleMark]

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.
:rockon:

[FSJ Guy]

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).

[EagleMark]

This covers wiring of MSD 6a in all applications including installing it in a stock EFI system.

[jeepboy45]

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!

16311632

[EagleMark]

Got me? Have you traced the wires back to PCM? Wiring diagrams are here:
http://www.gearhead-efi.com/Fuel-Injection/showthread.php?335-16188051-and-16181333-PCM-Information-EE-EEB

[jeepboy45]

This covers wiring of MSD 6a in all applications including installing it in a stock EFI system.

This is the current MSD config:1634


I could be reading/understanding this ALL WRONG, but here goes...... The MSD module would get abandoned. Using hybrid dizzy as you mentioned earlier in thread, the dizzy would be connected directly to ECM, and ECM to coil?

My head is beginning to hurt!

[Six_Shooter]

The ignition module gets connected to the ECM, to both trigger the ECM and allow the ECM to control timing. The igniton control module also triggers the MSD box. Look at the points trigger setup using the white wire.

[jeepboy45]

The ignition module gets connected to the ECM, to both trigger the ECM and allow the ECM to control timing. The igniton control module also triggers the MSD box. Look at the points trigger setup using the white wire.

I gotta clarify this: when you are referring to "ignition control module" or "ignition module" are you referring to the module inside the distributor, arent you? This is all new terminology to me. I get it now. I've been getting that confused with the old school ford "brain module" (crappy square box with epoxy melted in the back) Old school Jeep wiring had only that ford module and the dizzy...thats about it. I replaced that "brain" with the MSD....

I'm still trying to clarify if using that hybrid dizzy is a good way to go. At first glance it an AWESOME WAY TO GO. Using that hybrid will allow me to connect it to the ECM, and so on and so on like you just described... I get it now.

I'M SORRY FOR THE seeminly dumb questions..... I've gotten lost in some of the terminology that I'm still getting used to.

[EagleMark]

Yes the ignition module he is talking about is the EST. It is the module inside the EFI small cap distributor. You can also use your MSD 6a box with it.

[1project2many]

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...


Ooo! Ooo! Pick me! Pick me!
Bosch ABS unit from Corvette!
Sorry... just blurted it out. :(

(Image shamelessly stolen from http://www.corvetteactioncenter.com/tech/c4/abs/index.html

[JeepsAndGuns]

Ok now I'm getting confused. Are yall saying he can use the MSD box instead of the 8 pin HEI module (for the op, thats the ignition module used with a the 16197427 pcm we are talking about, and many others) Or are yall saying he can continue to use the MSD box WITH the 8 pin module?

[Six_Shooter]

He can use the MSD box with the 8 pin module.

[EagleMark]

Yup!
http://www.msdperformance.com/product.aspx?id=4685

[cmaje72]

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...

They are batch fire. 1 knock and 1 wire O2's.

[EagleMark]

Thank you for for clearing that up. Strange though they had OptiSpark distributor, which I know had some slight mechanical differences. I'm wondering if the sensor wheel was the same? It seems to be key in determining which cylinder is firing as all eight are differant, so I wondered what the cam sensor was needed for. From your info I'm guessing no cam sensor on 92-93 either?

[cmaje72]

Nope no cam sensor. 92-94 F-bodies had the non-vented opti. As near as I can figure mine came from a 94. I did modify my opti to vent it like the newer ones and the internals look to be the same as the later opti's. I have a spare b-body lt1 sitting on a stand in the garage and took it apart before I did the one in the truck just to get the hang of what needed to come apart. they are pretty similar excpet for the drive part on the back and the venting.

[EagleMark]

My research has shown just that. Early 1994 had the drive gear change but did not have the vent but was a dealer recall to do so. I have that paperwork with my car from dealer as it was upgraded to vented.

I also have one here taken apart, was told it can't be done! Ha! But then found the bearing is specail and no longer available. So buying a good aftermarket Opti with new bearing, using the stock sensor and wheel with new cap and rotor is still way cheaper than buying the entire unit new from GM. If I could have found a bearing it would have been a rebuildable part. Machining housing to new bearing would be more than buying one from like Chandler Motorsports who has 2 options, cheap one year warrenty, little more money for liftime warrenty. Lifetime warrenty has obvious better quality pickup sensor!

[woody80z28]

They are batch fire. 1 knock and 1 wire O2's.
So 92-93 are OBD1 batch fire...what about 94-95?
I know 88-93 Berettas are OB1 batch fire and 94-95 are "OBD1.5" that are sequential OBD1 masks that are flash ECMs, not Proms. Is this the same story for F-bodies as well? The 94-95 Berettas could not be tuned by anything AFAIK.

[EagleMark]

94-95 are SFI dual heated O2 sensors, dual knock sensors and OBDI and excellent XDF and ADX for TunerPro. No chip, flash PCM with $20 Winflash program from TunerCat.

Just have to figure out how to use it with stock EFI distributor and your set. It has a very high tech OptiSpark distributor. Look earlier in thread for hybrid machining ideas.

[JeepsAndGuns]

Wild idea after reading and learning about the optispark. You think there could be a way to mount the optispark on the front of a engine and run it off the crank, but use only the opti part, and then use the standard distributor on the engine your adding the injection to?


Err...wait, no that wont work, I forgot the opti runs off the camshaft, crank will spin it too fast.
You said in another thread not to delete bad ideas, so there ya go, I left my bad idea for all to see.