Gen3 vs. Gen4 differences

[iamdub]

Yes, this has been discussed all over the interwebz. This thread is mainly for consolidation and confirmation of info.

I'm considering swapping in a 5.3 or 6.0 Gen3 motor because I often find sub-100K to 150K mile units for $300-$700. I'm looking only at ones that are still in the vehicles so they can be ran and tested. I'm considering going this route instead of an AFM delete on my nearly-200K-mile Gen4. Of course, I'd inspect and test it as much as possible since I wouldn't know the history of it. My general idea is to get one from a clean and well-maintained SUV as these have a much lower chance of being abused.

I know the main functional differences are the 24X reluctor wheel on the crank, the cam sensor is in the front and the knock sensors are on the sides of the block. I'll swap my current timing cover over and screw the knock sensors into some unused bosses on the sides or drill and tap to put them into the same locations as they are on the Gen4. For the reluctor wheel, a buddy is "downgrading" a Gen4 he got a deal on to run on Gen3 electronics for his rock crawler rig and said I can have the 58x wheel.

I know the later blocks (2005?) have bigger/stronger rods and floating pins like my Gen4 and I plan to get one of these. I would also reseal it, replace the barbell, etc. before swapping it in. My questions are:

1) Are there any considerable strength differences in the blocks and/or would I be giving up anything else?

2) Could I remove the crank, swap the reluctor wheel and reinstall it (with new ARP and/or Katech hardware) while keeping everything (bearings, rod caps, etc.) in it's original location with no problem? My first thought is that this is a reckless idea and puts me at risk for a spun rod or main bearing. But, I read and hear of many doing exactly this with no problems as long as they follow the hardware torquing specs to a "T". I have a quality torque wrench with very little use and even lesser use since being tested and certified by a lab.

 

[swathdiver]

How much are the Gen IV equivalents Chris?

 

[iamdub]

How much are the Gen IV equivalents Chris?

I've only found ones already pulled at salvage yards on car-part.com. They seem to average a starting price of nearly $2,000 for 150K+ mileage units, then there's shipping. But this is pointless as they are still 5.3s with AFM and with unknown history. I bought mine at 146K, but have a decent record of the history with the two previous owners, one of which was the car lot owner's wife. Of course, the 6.0s and 6.2s are much higher.

I can get all the AFM delete stuff for mine for around $600-$800, including all fluids, etc. but it's still a 200K-mile mill. I guess I'm just trying to determine if it's worth the few hundred bucks I'd save to have a 50K-mile fresher engine. But, not if I'm sacrificing considerable strength and/or smoothness and/or risking spinning bearings by cracking apart the bottom end.

 

[swathdiver]

I've only found ones already pulled at salvage yards on car-part.com. They seem to average a starting price of nearly $2,000 for 150K+ mileage units, then there's shipping. But this is pointless as they are still 5.3s with AFM and with unknown history. I bought mine at 146K, but have a decent record of the history with the two previous owners, one of which was the car lot owner's wife. Of course, the 6.0s and 6.2s are much higher.

I can get all the AFM delete stuff for mine for around $600-$800, including all fluids, etc. but it's still a 200K-mile mill. I guess I'm just trying to determine if it's worth the few hundred bucks I'd save to have a 50K-mile fresher engine. But, not if I'm sacrificing considerable strength and/or smoothness and/or risking spinning bearings by cracking apart the bottom end.

I looked on CL in your area and saw a guy selling a freshened/rebuilt LC9 for $1500 in Picayne. Since she's not a DD anymore, why not just take your time and rebuild it? If it were me, I'd stick with the Gen IV architecture.

Wait, there's nothing wrong with yours now right? Weren't you thinking about going 6.2? If so, stick with that plan. Either buy an L9H or build one (6.6) out of a 5.3. Also remember that lots of Avalanches around our years also had the aluminum L76 6.0. That block with a 4" crank and you've got a 402.

 

[iamdub]

I looked on CL in your area and saw a guy selling a freshened/rebuilt LC9 for $1500 in Picayne. Since she's not a DD anymore, why not just take your time and rebuild it? If it were me, I'd stick with the Gen IV architecture.

I saw that LC9 a couple weeks back in the Gulfport, MS craigslist. I'm leery about rebuilt engines in general, especially from individuals. You never know the quality of their work and there's no real warranty.

She's not a DD, but I still need a vehicle I can jump in and go at almost any time, especially on the weekends. I'm working solo, but I'm confident that I can do an AFM delete or engine swap over the course of a week after work and finish it on the weekend. I surely don't have the time to remove, build up then reinstall an engine. I really don't wanna tear into one because 1) I'd be affecting the reliability of an engine built in a tightly-controlled factory environment and 2) I can't afford, time- and money-wise, the snowball of "WIHIMAW" that would ensue once I dove into it. I'm forcing myself to stick to the minimum that is logical and rational. Believe me- it churns my stomach to think that I'd actually tear into an engine to remove a cam and replace it with one of the same profile (AFM to non-AFM).

Wait, there's nothing wrong with yours now right? Weren't you thinking about going 6.2? If so, stick with that plan. Either buy an L9H or build one (6.6) out of a 5.3. Also remember that lots of Avalanches around our years also had the aluminum L76 6.0. That block with a 4" crank and you've got a 402.

Correct. It runs like a champ and doesn't burn any oil. It just has a lifter tick for about 3 seconds after startup that I'm taking as my warning for an impending AFM lifter failure. Sure, it may not be an AFM lifter making the noise, but you know that chances are hugely favorable that it is. It did this when I first bought it then subsided until fully going away after my 2nd ad 3rd oil changes with full synthetic. Now it has returned.

If something were to happen that required an engine replacement, I'd absolutely get a 6.2 since they aren't much more than a Gen4 5.3. Actually, it'd be about the same or even less when factoring in the cost of an AFM delete ($600+) on a replacement 5.3 before swapping it in. So, I'm always keeping my eyes peeled for a deal on one. In the meantime, I don't have the funds allocated to just buy an engine with everything going towards gearing up to move out of state. The current one is in great shape other than the lifter tick so I feel it's worth investing an AFM delete into it. I'm confident that ~$700 would be worth the peace of mind of having a reliable engine until I save up the play money for an L9H.

Seeing these Gen3 motors for half the cost of the AFM delete is what prompted all of this. But, the more I reflect on it, I'm thinking it wouldn't be worth the risk. Disassembling and reassembling a bottom end without "rebuilding" and checking clearances is too risky. There's no way things will be torqued or shaped the same way afterwards no matter how precise the fasteners are manufactured, especially on something as worn-in as a 100K+ mile engine. That $300-$500 saved could easily be lost and I'd be in worse shape than before with a roached rotating assembly. So, I should stick with what I know and just AFM-delete my current engine. I mean, the whole point of any of this is to have a reliable engine, ya know?

I didn't know about the Avalanche having the L76. I'd settle for one of those even though the power numbers aren't all that much higher than the 5.3. Speaking of, why wouldn't it be closer to the 400+ HP and TQ numbers of the 6.2 since it's only .2 liters smaller and .7 liters larger than the 5.3? Does it have a "weak" cam? I'll add the L76 to my search list, just in case.

 

[swathdiver]

I mentioned that motor because it was less expensive than a used pull. I'd still tear it down and inspect everything.

I understand time and money but don't sell yourself short that you rebuilding a short block would be inferior to the factory. I know you well enough even from keyboard to keyboard that you'd do just fine.

Didn't know you were planning on relocating, didn't you just put in a lift in your "Barn"?

While I've yet to get my hands on the internals of an LS engine, I've rebuilt and inspected plenty of Buick V6s and never had a problem opening them up, checking clearances and then either slapping new bearings in or bolting them back up.

The L76 Truck engine makes 367 HP and 375 FTLBS of Torque. That's splitting the difference between 5.3 and 6.2 to me. Good candidate for a 4" crank! Oh wait, I said that already! LOL The L76 camshaft's duration is similar to the 6.2s but the lift is less for whatever reason. There's something magical about those extra 22 cubic inches!

 

[iamdub]

I mentioned that motor because it was less expensive than a used pull. I'd still tear it down and inspect everything.

I understand time and money but don't sell yourself short that you rebuilding a short block would be inferior to the factory. I know you well enough even from keyboard to keyboard that you'd do just fine.

Didn't know you were planning on relocating, didn't you just put in a lift in your "Barn"?

While I've yet to get my hands on the internals of an LS engine, I've rebuilt and inspected plenty of Buick V6s and never had a problem opening them up, checking clearances and then either slapping new bearings in or bolting them back up.

The L76 Truck engine makes 367 HP and 375 FTLBS of Torque. That's splitting the difference between 5.3 and 6.2 to me. Good candidate for a 4" crank! Oh wait, I said that already! LOL The L76 camshaft's duration is similar to the 6.2s but the lift is less for whatever reason. There's something magical about those extra 22 cubic inches!

Oh, I wasn't doubting MY rebuilding skills. I've been plenty intimate with the internals of a few LSs and I know that I'm ridiculously particular enough that it'd be built more precise than factory. In that sense, I'm a control freak so I'd doubt other's rebuilding practices unless they were a very reputable professional.

Been planning a move to Alabama so almost all time and financial efforts are going towards getting my house ready for market. I assembled the lift, but it's not anchored down. I really just got the lift because I've always wanted one and it was a good deal. If I determine exactly where I want it, I'll drill some holes to see if the concrete is thick enough. If not, I'll sell it or disassemble it to move with us. If the concrete's good, I'll anchor it and use it. I can move it to AL if the new homeowner doesn't appreciate it as part of the deal.

I just double-checked the info I looked up earlier on the L76. What I read was 355HP/384TQ, which is "only" 29HP/36TQ more than my LMG. But, that was for the car version of the L76.

 

[thompsoj22]

Yes, this has been discussed all over the interwebz. This thread is mainly for consolidation and confirmation of info.

I'm considering swapping in a 5.3 or 6.0 Gen3 motor because I often find sub-100K to 150K mile units for $300-$700. I'm looking only at ones that are still in the vehicles so they can be ran and tested. I'm considering going this route instead of an AFM delete on my nearly-200K-mile Gen4. Of course, I'd inspect and test it as much as possible since I wouldn't know the history of it. My general idea is to get one from a clean and well-maintained SUV as these have a much lower chance of being abused.

I know the main functional differences are the 24X reluctor wheel on the crank, the cam sensor is in the front and the knock sensors are on the sides of the block. I'll swap my current timing cover over and screw the knock sensors into some unused bosses on the sides or drill and tap to put them into the same locations as they are on the Gen4. For the reluctor wheel, a buddy is "downgrading" a Gen4 he got a deal on to run on Gen3 electronics for his rock crawler rig and said I can have the 58x wheel.

I know the later blocks (2005?) have bigger/stronger rods and floating pins like my Gen4 and I plan to get one of these. I would also reseal it, replace the barbell, etc. before swapping it in. My questions are:

1) Are there any considerable strength differences in the blocks and/or would I be giving up anything else?

2) Could I remove the crank, swap the reluctor wheel and reinstall it (with new ARP and/or Katech hardware) while keeping everything (bearings, rod caps, etc.) in it's original location with no problem? My first thought is that this is a reckless idea and puts me at risk for a spun rod or main bearing. But, I read and hear of many doing exactly this with no problems as long as they follow the hardware torquing specs to a "T". I have a quality torque wrench with very little use and even lesser use since being tested and certified by a lab.

just my thoughts but in the end i think that you would end up in the same "pin pulled grenade feeling" similar to how you feel about your current engine? Can you pull caps and remove the crank to do the reluctor swap and reinstall? Yes, But it go's against the "do it right the first time" method. I think it would be better to deal with the negatives of your current engine and build your replacement over time. When your finished and your new engine is installed you will have complete confidence and satisfaction in the project. If there were a way to purchase a direct replacement salvage engine "without" having to retrofit internal components than i could understand the cost savings and the gamble of getting a good engine that will last another 100k trouble free miles.

 

[iamdub]

just my thoughts but in the end i think that you would end up in the same "pin pulled grenade feeling" similar to how you feel about your current engine? Can you pull caps and remove the crank to do the reluctor swap and reinstall? Yes, But it go's against the "do it right the first time" method. I think it would be better to deal with the negatives of your current engine and build your replacement over time. When your finished and your new engine is installed you will have complete confidence and satisfaction in the project. If there were a way to purchase a direct replacement salvage engine "without" having to retrofit internal components than i could understand the cost savings and the gamble of getting a good engine that will last another 100k trouble free miles.

Yes. This is the conclusion I came to after giving it a little more thought. I would have MUCH more faith in my current 5.3 with an AFM delete than in what would essentially be a "hacked" 5.3 reluctor ring swap, regardless of the 50,000+ mile difference.

So, I'll proceed as planned and do the AFM delete on my 5.3 to have a motor that I'd feel confident with for ~$700. In the meantime, I'll continue to look for what I REALLY want without being rushed by a ticking time bomb (pun intended).

 

[BourbonNcigars]

In the meantime, I'll continue to look for what I REALLY want without being rushed by a ticking time bomb (pun intended).

Jesus, man...you type some walls of text. I simultaneously applaud and condemn you. At least you have the forethought to make paragraphs. So, forgive me if I missed something, but in reference to your comment above (ticking time bomb), is your engine already exhibiting signs or are you just going off precedence set by the AFM 5.3?