Choices to make, experience needed.

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blackhawk17

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Ok, so I've been around here for a while. I've got a 92 Z71 that is my daily driver, and I intend to keep it. I've got an appointment to get it painted, and I'm working on the suspension, and I really would like to keep the old thing. I like old things and in this day where a car payment runs $600 or more, I'd rather save that money and put some of it into this. It doesn't need anything to be a daily driver (it has been for 5 years), and with new paint it will genuinely be a nice looking truck. I'm pretty attached to it.

I foolishly bought a 2000 k3500 dually sight unseen in the spring when I got back from Afghanistan. It's purpose was to pull our camper and be my new daily driver. Paid too much, spent too much, sold it for too little. It looked good, but it was too much trouble to fix all of the gremlins. My old 92 was in better shape.

I know that most of you older fellas have had many of these trucks, but have finally moved on and updated to more powerful, more comfortable machines, but I'm not ready to do that. I still want to hold out and have a classic for as long as possible.

Money is not as much of a concern as it used to be, so I'm okay with spending a little money. After all, I'm about to have to rebuild/replace the drivetrain anyway.

Additionally, I'd like to be able to tow about 7,000 lbs comfortably (my max), so we're looking at some real numbers, not "ultimate TBI mods" kind of stuff, no offense. I know the trans will need upgrading. We have a newish (2016) that I thought we were going to sell, but it looks like we're going to keep it.

I obviously want to stay with fuel injection, and I need low end power, not a high RPM LS race motor. Maybe a 454 or 6.0? I'm pretty much assuming that I won't be able to keep the TBI 350 unless I want forced induction from what I've read- but that makes me worry about reliability.

I have 3.73 gears and don't really want to change them, and I'd like to stick with my 33" tires. I've done some research, and I'm not 17 years old, so I know that we're talking money and time. I'm just hoping there is someone out there who has legitimately done some of this stuff and can tell me if the juice is worth the squeeze.

Additionally, I'm in the Clarksville, TN area and am in the market for a good shop to perhaps do some of the above-mentioned work if I'm unable myself. So if anyone local has any recommendations I'd be much obliged.

Thank you for your experienced responses.
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Tom P

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I will preface my response saying that I have not done the swaps that you are considering doing but I do have some input based on the fact that I have owned vehicles with the engines you are considering.

I like my 454. I'll like it even more when I get the kinks ironed out of it. It is capable of some serious power with some intermediate modifications. It will probably fit your truck a little easier than an LS would, but not by much. A built 4L80E would be my first choice for transmission. You can find them easily and for a reasonable price. Stand alone tuning or a 0411 swap is going to be necessary for whatever you end up doing.

A 6.0 would be a fantastic option if you had more money and time to play with. I used to dislike them based solely on the opinions of others, but I own one now and it has been a great engine. Its in a Yukon Denali, so its difficult to get a "truck perspective" out of it but we have pulled our travel trailer with it on a few occasions and it does a fantastic job despite being long legged. I know others who have them in trucks and like them very much for towing. They have, in a sense, become the new workhorse engine, especially since the death of the 8.1L.

My only opinion that counters your plan is to add some gearing to your rear end. I had 3.73 gears with 33's in a half ton and while it was fine day to day, towing hills was a huge struggle. I could not keep the engine in the power band. I would highly recommend dropping a 4.10 set, but thats my $.02.
 

dylan5299

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I'll x2 with the 6.0 and gearing. My truck came stock with 3.73 and it was up'ed to 4.10's when I get my new 33's. it is definitely a noticeable difference and I recommend it. Coupled with the 6.0 and a tune and you'll be the little engine that could.
 

digdug18

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You stated that you have a 1992 Z71, but which tonnage do you have? K1500, k2500, or k3500?

I ask because you’ll want to haul using a frame that is designed to haul such a load. Yes, you can upgrade the motor, and brakes, but going to the expense of upgrading the frame as well, and you’re into the cost of a completely different truck.

As for what to do for more power, first decide if you want gas or diesel, then decide your power goals. For diesel, I’ve a buddy that put a dodge Cummins in a k3500, and it’s been a wonderful truck for the past 100k miles.

Gas, of the other hand the 454, that came in other models of the same year is a pretty straight forward swap.

Honestly though if it were me, I’d seek out a rust free Arizona truck, and pay the $600 to ship it to wherever you live, buy what yo want and save the money. Keep your daily driver, just that.


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Tom P

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You stated that you have a 1992 Z71, but which tonnage do you have? K1500, k2500, or k3500?

IIRC the z71 package was only optioned on the K1500. Although a K1500 will handle 7000 lbs, you would usually desire more power and better gearing. If the truck is rated to 7000lbs (using that figure generically here, so dont jump down my throat), then a stronger frame is not required to tow 7K lbs, and engine, suspension and axle upgrades will make it a more worthy truck without requiring frame upgrades.
 

Christian Steffen

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If you're looking for votes, I throw one towards a 454 with a tune or a tune and modifications, for towing anyway. The 454 will make more torque than the 6.0.

The 6.0 will beat it out for mileage while just driving around, but I think the 454 will get better mileage while towing. At least the one experience that I had with using a 6.0 for towing indicated that.

4l80e will work fine with either option as long as its a gen 3 6.0.
 

blackhawk17

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Yeah, I've pretty much settled on the 7.4 at this point. My plan is to buy a rebuildable core and 4l80- attached if I can find one, and while I'm deployed have it done, and throw a few speed parts at it, nothing crazy because it's my daily. It'll be more thirsty than the 6.0, but it's a relatively light truck and I think I'll stick with 3.73 gears. Plus I think it'll be a much simpler swap. I know that the TBI 454 is kind of a dog, especially compared to these newer LS motors, but even stock it'll be enough for my needs, plus a few simple mods should do me well without sacrificing reliability.



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blackhawk17

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This truck is rated at 7000. Most of the K1500's were 6500, but with the F44 suspension package (RPO code) it has the 14 bolt and bigger brakes. It raised the GVWR and the tow rating, though not by much admittedly.

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JCribb

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I used to be in Clarks-vegas five years ago, but I retired and went back to where I grew up, before just recently coming back east a little. Since it has been so long I wouldn't know who does what around there.

I have a 94 Z71, I don't recall if mine has the RPO code F44 or not, but I do know mine was born with GT4 G80 10 bolt (3.73 gov lock), and after killing off my 10 bolt I upgraded to the 6 lug 14 bolt with 3.73's open diff (I hate the open carrier :()

I have a good portion of the TBI mods if not all of them done, and I can still get 15 mpg on the highway, but I also have big ol huge bumpers from and rear. I hope to lift it up and run 33's or 35's (I haven't decided yet) but I know I will need to upgrade to 4.10's to put my power level back where it belongs.
 

blackhawk17

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I've been talking to Brian Harris from TBIchips, and it looks like the big block is the way to go. A gen V block with Comp Cams K11-412-8 with 18cc domed pistons should turn around 470-500 lb/ft at a reasonably low RPM according to him.

That all sounds good to me, so the next issue I have to make a decision about is where I'm going to get the motor. Should I just buy an engine from EBay or some builder or would it save me money to find a block, have it rebuilt and throw in the valve train I want? This is my daily, and I'm looking to ultimately have this thing down for as short a period as possible. I don't have time to let it sit and become a weekend-week-month long experiment. I'd love to do it myself but I can't afford to screw it up and have it costing me even more time or money.

I've talked to 1951Herb on EBay, who is an engine builder, and he'll build me a Gen V like I'm wanting for $4,400. I'd be modifying the TBI system, but I'm not sure to what end yet. The price above doesn't include intake or TBI set up on top. I'll have to work that out separately. Additionally I'm going to need a 4L80E with stand alone controller. A reman 4wd 4L80E I can get for around $1700, and around $200 for the controller.

So clearly this is adding up in cost. It's going to be taking place over the next 12 months so it won't be all at once, but I'm wondering if it is reasonable to pay that much for the motor, or should I just find a local builder and have them rework a block I find, and then add my parts. Around $920 for the valve train and $700 for the piston set. I found a good block for $700, but that of course doesn't include labor for the machining and assembly. By rough math it doesn't sound like I'll come out much on top by piecemealing it together. Not to mention the trouble I'd save by just buying the assembled motor.
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