Thanks for the add!
My '99 2 door Tahoe has been mothballed since March. I had a #5 cylinder missfire with no compression. I came across a '94-'96 LT1 out of an Impala with 95,000 miles. It had been laying around fro several years and several generations of wasps and hornets called this thing home. The crank turns freely, but all of the accessories are crap. I got the motor dirt cheap, so its already here. There's no need to comment on what other motor would be better. I already have it on the stand with the accessories removed.
I'm pulling the bad Vortec 5.7 little by little. I didn't label any of the connectors, since everything is going to be different with the replacement. Everytime I ask someone a question about this swap, I'm told to "go look at the forums". Well, all I see on the forums are varying opinions about the LT1 vs the LS series, and who's cam is bigger, who's opinion is more valuable, etc. etc. I'm looking for REAL answers from someone who has done this with an LT1. As I said, that is the motor I already have and that is the motor I am going to use unless there is some reason why it is impossible.
First, I want to run a compression check on the LT. In order to do that, I need to hook a starter up to it and spin it. So, I pulled the Tahoe's starter and it misses the flywheel by 1/2". I assume the Impala uses a 153 tooth flywheel and the Tahoe uses the 168. Question 1: Can I just swap the flywheels, or do I need to replace the starter? That takes me right to question 2: Will the smaller flywheel mate to the torque converter, or is there an adapter kit, or back to question 1, can I just swap flywheels?
Assuming the LT passes the compression check, and I can proceed with replacing the bad accessories, question 3: can I use a water pump and complete cooling system from any of the LT1 gen II equipped vehicles? I'm pretty sure I have plenty of room between the motor and the radiator in the Tahoe to use whatever I want, but if there is one that would work better, that's what I want to know. I understand there are some hose kits that will enable me to use my existing radiator, but I'll need the appropriate sensors, fan controllers, etc.
Question 4: How do I check the intake on the LT? Aside from just cleaning it up, is there anyway to make sure it's going to work? Same goes for the injectors. Replacing all 8 is cost prohibitive and I might as well start all over with a crate Vortec. Again, proceeding with this swap is entirely contingent on the motor working properly, (as I was told it was when pulled). Accessories and fitment are the main concern as long as the motor will run. My power steering pump, AC, and alternator from the Tahoe will work fine.
I am planning on using headers and running true duals with the cats, (so I don't get hemmed up). I have the spare tire mounted inside the truck, so I have all the room in the world down the driver's side to run a full pipe. I really don't know why GM had to cross over the driver's side tube in the first place. Question 5: Shortys, mid-length or long tubes? Is there a particular brand/style specifically made for a 4x4 2 door GMT400? I saw a YT video of a dude installing long tube headers and he had some super tight clearance issues I would not have accepted...not with a 4x4 and the intention of ever taking it off road.
Lastly, question 6: Would it be better to acquire a Impala wiring harness and ECM, or should I have the Tahoe's ECM reprogrammed to run the LT1? What modules/components will require different connectors to couple with my existing harness?
This is the first time I have swapped a motor in anything. I've had some good guidance so far and I am definitely taking all the time in the world. I haven't broken anything (yet)
and I haven't discarded anything I might need later. All of my hardware seems to be in good shape, so I'm not planning on investing $$$ in a ton of ARP hardware right now. I may cam-up the LT1, but that might require another session of programming the ECM. I don't know. Other than these pressing questions, I think I've got this. I realize I'm going to have to spend some money to make this work, but if I come out at or below the cost of a crate Vortec, I'm doing okay. Thanks for the help!
My '99 2 door Tahoe has been mothballed since March. I had a #5 cylinder missfire with no compression. I came across a '94-'96 LT1 out of an Impala with 95,000 miles. It had been laying around fro several years and several generations of wasps and hornets called this thing home. The crank turns freely, but all of the accessories are crap. I got the motor dirt cheap, so its already here. There's no need to comment on what other motor would be better. I already have it on the stand with the accessories removed.
I'm pulling the bad Vortec 5.7 little by little. I didn't label any of the connectors, since everything is going to be different with the replacement. Everytime I ask someone a question about this swap, I'm told to "go look at the forums". Well, all I see on the forums are varying opinions about the LT1 vs the LS series, and who's cam is bigger, who's opinion is more valuable, etc. etc. I'm looking for REAL answers from someone who has done this with an LT1. As I said, that is the motor I already have and that is the motor I am going to use unless there is some reason why it is impossible.
First, I want to run a compression check on the LT. In order to do that, I need to hook a starter up to it and spin it. So, I pulled the Tahoe's starter and it misses the flywheel by 1/2". I assume the Impala uses a 153 tooth flywheel and the Tahoe uses the 168. Question 1: Can I just swap the flywheels, or do I need to replace the starter? That takes me right to question 2: Will the smaller flywheel mate to the torque converter, or is there an adapter kit, or back to question 1, can I just swap flywheels?
Assuming the LT passes the compression check, and I can proceed with replacing the bad accessories, question 3: can I use a water pump and complete cooling system from any of the LT1 gen II equipped vehicles? I'm pretty sure I have plenty of room between the motor and the radiator in the Tahoe to use whatever I want, but if there is one that would work better, that's what I want to know. I understand there are some hose kits that will enable me to use my existing radiator, but I'll need the appropriate sensors, fan controllers, etc.
Question 4: How do I check the intake on the LT? Aside from just cleaning it up, is there anyway to make sure it's going to work? Same goes for the injectors. Replacing all 8 is cost prohibitive and I might as well start all over with a crate Vortec. Again, proceeding with this swap is entirely contingent on the motor working properly, (as I was told it was when pulled). Accessories and fitment are the main concern as long as the motor will run. My power steering pump, AC, and alternator from the Tahoe will work fine.
I am planning on using headers and running true duals with the cats, (so I don't get hemmed up). I have the spare tire mounted inside the truck, so I have all the room in the world down the driver's side to run a full pipe. I really don't know why GM had to cross over the driver's side tube in the first place. Question 5: Shortys, mid-length or long tubes? Is there a particular brand/style specifically made for a 4x4 2 door GMT400? I saw a YT video of a dude installing long tube headers and he had some super tight clearance issues I would not have accepted...not with a 4x4 and the intention of ever taking it off road.
Lastly, question 6: Would it be better to acquire a Impala wiring harness and ECM, or should I have the Tahoe's ECM reprogrammed to run the LT1? What modules/components will require different connectors to couple with my existing harness?
This is the first time I have swapped a motor in anything. I've had some good guidance so far and I am definitely taking all the time in the world. I haven't broken anything (yet)
and I haven't discarded anything I might need later. All of my hardware seems to be in good shape, so I'm not planning on investing $$$ in a ton of ARP hardware right now. I may cam-up the LT1, but that might require another session of programming the ECM. I don't know. Other than these pressing questions, I think I've got this. I realize I'm going to have to spend some money to make this work, but if I come out at or below the cost of a crate Vortec, I'm doing okay. Thanks for the help!
