LY6 in a '76 GMC
Thread Starter
On The Tree
Joined: Jul 2006
Posts: 101
Likes: 0
From: Upstate South Carolina
My motor came with a 4L80E behind it. I assume the same flexplate would be used with the 6l80e and 6l90e but am not sure.
The swap still runs perfectly. I quit screwing around with the tune so I could pull out my wideband and concentrate on the L76 I am putting in my Chevelle. I know I could up the high octane timing tables a bit and get a little more out of it.
The motor really makes the truck fun to drive. It is offically too much motor for my crappy old truck as it will get you moving way faster and way quicker than it has any right to. Driving it around normally the motor is a behaves perfectly. Smooth and quiet, dropping down to idle at just 550rpm at stop lights. With a 3.07 rear and the 1:1 of the TH350 it runs about 2500rpm at 70mph. I am getting right at 15mpg overall with the swap and that includes little interstate driving and my romping on it all the time. I plan on swapping in my 4l80e when I pull it from my Chevelle. With the lockup and overdrive it should return over 20mpg on the highway and hopefully over 15mpg around the backroads.
Oh, with the Richmond Powertrax installed you have to be pretty respectful of it in the wet. Both rears will break loose if you jump on it. Second gear at 70mph the other day broke both rear tires loose on the interstate and made it interesting catching it before it decided to swap ends.
The swap still runs perfectly. I quit screwing around with the tune so I could pull out my wideband and concentrate on the L76 I am putting in my Chevelle. I know I could up the high octane timing tables a bit and get a little more out of it.
The motor really makes the truck fun to drive. It is offically too much motor for my crappy old truck as it will get you moving way faster and way quicker than it has any right to. Driving it around normally the motor is a behaves perfectly. Smooth and quiet, dropping down to idle at just 550rpm at stop lights. With a 3.07 rear and the 1:1 of the TH350 it runs about 2500rpm at 70mph. I am getting right at 15mpg overall with the swap and that includes little interstate driving and my romping on it all the time. I plan on swapping in my 4l80e when I pull it from my Chevelle. With the lockup and overdrive it should return over 20mpg on the highway and hopefully over 15mpg around the backroads.
Oh, with the Richmond Powertrax installed you have to be pretty respectful of it in the wet. Both rears will break loose if you jump on it. Second gear at 70mph the other day broke both rear tires loose on the interstate and made it interesting catching it before it decided to swap ends.
Teching In
Joined: Feb 2011
Posts: 4
Likes: 0
Buddy
Can you send me any details on a ly6? Mostly I need the diagram and any info you got will help me out alot. I'm installing it on a 64 swb. Gama6970@hotmail.com
Can you send me any details on a ly6? Mostly I need the diagram and any info you got will help me out alot. I'm installing it on a 64 swb. Gama6970@hotmail.com
Thread Starter
On The Tree
Joined: Jul 2006
Posts: 101
Likes: 0
From: Upstate South Carolina
What kind of details are you looking for? I don't have the wiring diagram at hand, I will try to email it to you later tonight. Do you already have a LY6 or are you looking for info on them?
As an update, the motor in my truck is running great. Not a single problem, cranks and runs perfectly every time. I am still planning on swapping my 4l80e out of my Chevelle into the GMC, but I am remodeling my kitchen and don't have time. I am hauling construction waste off in it and new supplies in a few times a week. It is so nice to be able to jump in the GMC and take off without waiting for it to warm up enough not to be fussy. It is still spooky fast. I need to do some serious suspension work on it, if not to match the motor than to at least make it less of a scary ride above 80mph.
As an update, the motor in my truck is running great. Not a single problem, cranks and runs perfectly every time. I am still planning on swapping my 4l80e out of my Chevelle into the GMC, but I am remodeling my kitchen and don't have time. I am hauling construction waste off in it and new supplies in a few times a week. It is so nice to be able to jump in the GMC and take off without waiting for it to warm up enough not to be fussy. It is still spooky fast. I need to do some serious suspension work on it, if not to match the motor than to at least make it less of a scary ride above 80mph.
Staging Lane
Joined: Jun 2011
Posts: 80
Likes: 0
From: Lena, WI
Buddy,
Being that your LY6 is Drive by wire, what did you do with your detent cable on the TH350? Or are you using a manual valve body where you don't need kickdown? Just wondering because I am looking at putting an LY6 with VVT in front of my 700R4 but I'm unsure of how to adapt the detent to the throttle. Any info would be greatly appreciated. Thanks.
Being that your LY6 is Drive by wire, what did you do with your detent cable on the TH350? Or are you using a manual valve body where you don't need kickdown? Just wondering because I am looking at putting an LY6 with VVT in front of my 700R4 but I'm unsure of how to adapt the detent to the throttle. Any info would be greatly appreciated. Thanks.
RJ take a look at froejoe's first post in his build thread here. He adapted his TH350 kickdown cable to the throttle pedal assembly. You could probably do something similar with your 700R4. I don't know what pedal assembly you're using, but I know the one that came with my '07 Silverado donor vehicle wouldn't adapt easily. I'm eyeballing a C6 'vette pedal - still need to check into electronic compatability.
Thread Starter
On The Tree
Joined: Jul 2006
Posts: 101
Likes: 0
From: Upstate South Carolina
Good question. I am not planning on the TH350 being a permenant transmission for the swap. I am planning on using the 4l80e I had in my Chevelle in my truck. So for the time being I am running the TH350 without a kick down cable.
I think you could create the equivalent of a TV cable set up to the pedel like was suggested above. I have worked with the 700r4's a great deal and don't see why it would not be possible with some experimentation.
Good luck with it and keep us posted.
I think you could create the equivalent of a TV cable set up to the pedel like was suggested above. I have worked with the 700r4's a great deal and don't see why it would not be possible with some experimentation.
Good luck with it and keep us posted.
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Helpful thread Buddyholly but I have a question regarding the tach.
Im familiar with the pull up circuit and setting the tach output to crank seems straight forward enough but where on the ECM did you source a signal from? I heard from another member that its pin 48 on the X1 connector that the tach signal comes from is this what you did? I looked at the Mitchell schem and see there is no lead from the factory on pin 48 so did you add it yourself? Thanks man
I had to set my tach output to "crank" with a high and low resolution of 15 to get my tach to work. I also had to add a tach wire from the e38 ecu and use a pull up circuit. The tach was a pain to get to work.
Last edited by cam; Oct 19, 2011 at 09:28 AM.
Im running LS1 accessories so the alternator plug is different than the L92 ( assuming its the same as the LY6 also ) plug. THe dang Ritchie schem just lists the two wires on the LY6 alt plug as "charging system" and doesnt clarify what each one does. My LS1 was a single wire exciter with a single wire out for the volt meter. Question is do I need to attach both "charging system" leads or can I run just one to excite the alt and if so which one? Soooooo close now
Okay scratch all above issues Im trying to start it now but no spark. I disabled VATS 1+2 but cant seem to find where to disable starter in HpTuners? Any help here would be most appreciated as I have a fine bottle of Scotch waiting to crack once this sucker lights up.
Staging Lane
Joined: Nov 2008
Posts: 91
Likes: 0
From: Central NJ
Thread Starter
On The Tree
Joined: Jul 2006
Posts: 101
Likes: 0
From: Upstate South Carolina
Sorry for the delay, just got notification of your post. I am limited in how helpful I can be because I loaned my laptop with HP Tuners and my wiring diagram to a friend when we were getting his L92 drag motor running. Now I just disabled the VATS and the starter disable on that motor so it is fresh in my mind. The VATS you found but the starter disable was right there with it as I remember.
On the alternator issue I just looked at the wiring on my LY6 in my truck. Two wires to the alternator and I do not know what they do. If you are running the LS1 alternator I guess you should just wire it like the LS1. 1 wire for the exciter sounds like a winner.
On the alternator issue I just looked at the wiring on my LY6 in my truck. Two wires to the alternator and I do not know what they do. If you are running the LS1 alternator I guess you should just wire it like the LS1. 1 wire for the exciter sounds like a winner.
I just walked back into my office from trying everything imaginable thanks much for your prompt replies. So at this point I have it running and the issue was in the system folder but I dont know why or wtf is happening? If I disable starter diag then it starts and runs great but as soon as I turn the key off and try to restart? It only runs on 3 cyls. I tried disabling the clutch interlock and the same thing. I disabled both and the same thing. Ive tried write calibration only and flashing entire ECM and end up with the same result. The first time I have it purring NICELY on all 8 and then I key it off and back to 3 cyls and no gas pedal response either I should note. But to be clear there is no starter check enable/disable in my OS as Im on an L92 and I guess thats just one of the differences even though Im on an e38 ECM.
Anyways Im delighted its running but I have some tuning issues to sort out thats for sure. Any input is most welcome but Im gonna have a drink or three now and pass out
Anyways Im delighted its running but I have some tuning issues to sort out thats for sure. Any input is most welcome but Im gonna have a drink or three now and pass out
Staging Lane
Joined: Nov 2008
Posts: 91
Likes: 0
From: Central NJ
Congrats on the start, feels awesome doesn't it? Weird about the starter check not being in the OS. Stupid question (because it happened to me), did you try switching the views (beginner, standard, advanced)? Maybe that would show it. I am way too much of a newb to help with your running on 3 cyl issue. Probably something really simple to fix too. Good luck and congrats again.
TECH Apprentice
Joined: Nov 2011
Posts: 346
Likes: 7
From: Tampa, FL
Just starting to install 2009 LY6 and 4L85E and wondering about wiring, came as a complete pull out, harness, pedal, ecm, tcm. Would love to have a copy of your harness and how you added fuses/realys. Looks like there a bunch of wires that could be removed?? anyways, any help would be nice
Teching In
Joined: Jan 2014
Posts: 13
Likes: 0
Late to the Party The wiring diagram for this motor was from a Mitchell manual. Someone from the boards sent it to me and I pieced it together from 4 files and created a large .tiff photo. I printed it out in 8 parts and taped that together to make one huge color diagram. I would post a .jpeg version of it but is still over 1mb and I can't attach it through this site.
I bought a subscription to alldatadiy.com and found the diagram almost useless. It would tough to use in a stock vehicle but it did not show enough of the entire diagram to allow me to modify the harness. It was useful for identifying sensors and some other stuff but I would not recommend it.
I bought a subscription to alldatadiy.com and found the diagram almost useless. It would tough to use in a stock vehicle but it did not show enough of the entire diagram to allow me to modify the harness. It was useful for identifying sensors and some other stuff but I would not recommend it.
It seems that this Mitchell diagram is a pretty hot item on this thread and it just might be the key to some of the issues I having trouble solving. Is there a way I can get a copy of that document to help with this build?By the way, I am new to the site. I generally hang out over in a K5 forum but not getting the LS tech information I am looking for there . . . mostly mechanical install and a lot of very good 4WD stuff. The mechanical I think I have pretty well solved, but the controls are the part of the equation at this point that I am starting to dig into and am having a bit of a time finding the information. I also figure that with a site name like LS1Tech, there has to be some pretty sweet tunes and mods that will fit nicely with this swap.
I can provide an email address to float that diagram to. Just let me know from where it may be available.
Duke