LC9 swap out for LM7

Walter Manager Washington Posted   Latest   Edited  
Resolved
Propulsion
2007 Chevrolet Avalanche 5.3L (LC9) 4-spd (4L60-E) — 3GNFK12327G305868

Customer is swapping in an LM7 for an LC9. Cam and crank sensors are on different voltages, tone ring was already changed to a 54 tooth. What are my nightmares going to be? This looks to be a mess.

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Brad Diagnostician
Washington
Brad
 

I think it will be a mess. What year did the LC9 come out of? Same year?

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Walter Manager
Washington
Walter
 

LC9 was the original engine in the 2007 Avalanche. A 2003 LM7 is what is going in (AUGHHHHHHHHH!)

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Walter Manager
Washington
Walter
 

Tried to sell him a reman LC9 with a DOD delete, but he went and got his own.

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Albin Diagnostician
Washington
Albin
 

Walk away from this job. Otherwise, you will need a divorce attorney.

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Brad Diagnostician
Washington
Brad
 

Okay, I thought it was the other way around for some reason. Been a long day. The LC9 has AFM and in 2010 has VVT. IDK off of the top of my head if the injectors and such are the same. You are going from a GEN IV to GEN III LS based engine. Can it be done. Yes. But anything can be done with time and money. My advise would be find another GEN IV engine. This sounds like it will be no fun at…

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Gary Owner/Technician
Colorado
Gary
 

This sounds like it will be no fun at all. You're The Man, Brad… :0)

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Scott Owner/Technician
Michigan
Scott
 

Okay assuming you meant that the ckp reluctor has already been changed to the 58 tooth one (hopefully by someone competent that had the correct alignment tool) You will need to use the 2007 avalance ckp and cmp sensors and use the timing cover from the 2007 avalance (where the cmp sensor is mounted) The cam gear / sprocket will have to be replaced with a 4x signal reluctor unit that uses 3…

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Gary Owner/Technician
Colorado
Gary
 

Talk about going down a Rabbit Hole… :0)

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Zachary Mobile Technician
Texas
Zachary
 

I believe the injectors on the LM7 are different than the LC9, particularly if his Avalanche is a flex fuel model. I know that was true of the Z vs T vin LM7s. On a separate note Walter, I hope you're charging by the clock hour or something similar on this job. The amount of time you're going to end up investing in this is way outside the scope of a typical engine swap. Not to mention the fact…

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Scott Owner
California
Scott
 

Hi Walter, I'm assuming the customer had a problem with the AFM system and wants to go with an engine without that 'feature'? I'd say anything is possible given enough resources, as in time and money - Is it a wise idea? Not, in my opinion. I'd say a new/remanufactured LC9 with the delete, or without the delete, or a LY6 which is a 6.0L, or a L92, which is a 6.2L. Both the LY6 and L92 were…

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Michael Mobile Technician
Utah
Michael
 

Walter, Any time I have agreed to do something like this for a customer it has come back and bit me hard. When working at a shop we would have a flat bay we called the “Eternal Bay”. This is the one where the weird projects went. Some stayed for months, some for longer. Your customer will need to plan on all kinds of headaches including network incompatibilities and lights on the dash. I would…

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Albin Diagnostician
Washington
Albin
 

No good deed goes unpunished.

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Ricardo Diagnostician
Michigan
Ricardo
 

Every time I've seen a shop tried this it never worked right. I've seen swapping sensors , reluctors , harnesses, ECUs, installing the aftermarket tone counter converter etc. And never seen it work right. I'm sure it can be done but it's going to be a rlong and expensive journey Hope you have a bay that can be tied up for some time.. Every time I get called to diagnose a swap I had to…

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Gary Owner/Technician
Colorado
Gary
   

Hello, Ricardo. Speaking from experience, even an Old-School swap on a non-computer vehicle can get complicated. Nobody wants to pay for tying up a bay while waiting weeks and maybe months for parts. Many restoration shops want a $10,000 deposit up front plus storage costs when the vehicle has to be stored outdoors. So why should we be doing this for nothing?

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Walter Manager
Washington
Walter Resolution
 

Actually not that bad. With the tone ring changed over, we used the LC9 crank sensor. Then got an adapter harness from Summit for the cam sensor. After that it is pretty much a straight swap over. Used a tuner to program out the DOD system.

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