5.7 Rebuild or replace with a 5.3 LS?

[Spareparts]

Thank you all for your opinions. It really firms up the decision. I am sticking with the 350. Now to decide if I should have it rebuilt or say "F it" and attempt it myself.

Rebuild can turn into a rabbit hole with many options man. Be careful

 

[Schurkey]

Rule-of-thumb: Everyone screws-up their first engine rebuild.

1. They can be told a hundred times that stuff has to be CLEAN. Folks don't understand HOW clean, until they see the results of debris on 500-mile bearings, or 500-mile scuffed piston skirts, etc. If there's anything useful that the Virus Originating in the Wuhan Lab taught us, is that almost no-one washes their hands properly. Even fewer wash engine parts enough.
2. Approximately the same thing goes for tightening fasteners. What isn't under-torqued gets over-torqued; and if a torque wrench is used it's either not in calibration or it's used improperly. Yes, it matters what lube is on the threads and under the bolt-heads.
3. Failing to account for re-machining of used parts. Either stuff that needs to be machined doesn't get reworked, or stuff that gets reworked changes the relationship of the parts to one another leading to air or oil leaks, improper compression, quench/squish, cam/crank distance, wrong pushrod length, etc.
4. Going wild on parts selection. Too many folks want a hot-rod cam, and idle lope even when that's the last thing they need for a good-running truck engine.

 

[L31MaxExpress]

Rule-of-thumb: Everyone screws-up their first engine rebuild.

1. They can be told a hundred times that stuff has to be CLEAN. Folks don't understand HOW clean, until they see the results of debris on 500-mile bearings, or 500-mile scuffed piston skirts, etc. If there's anything useful that the Virus Originating in the Wuhan Lab taught us, is that almost no-one washes their hands properly. Even fewer wash engine parts enough.
2. Approximately the same thing goes for tightening fasteners. What isn't under-torqued gets over-torqued; and if a torque wrench is used it's either not in calibration or it's used improperly. Yes, it matters what lube is on the threads and under the bolt-heads.
3. Failing to account for re-machining of used parts. Either stuff that needs to be machined doesn't get reworked, or stuff that gets reworked changes the relationship of the parts to one another leading to air or oil leaks, improper compression, quench/squish, cam/crank distance, wrong pushrod length, etc.
4. Going wild on parts selection. Too many folks want a hot-rod cam, and idle lope even when that's the last thing they need for a good-running truck engine.

I think the Hecho En Mexico GM crate engine I just rebuilt was built by a first-time builder. Almost every piston ring end gap was lined up, had numerous stretched head bolts, and finally it had a cam retainer plate bolt that had backed off and the cam sprocket was grinding on it for self-clearance.

 

[0xDEADBEEF]

I think the Hecho En Mexico GM crate engine I just rebuilt was built by a first-time builder. Almost every piston ring end gap was lined up, had numerous stretched head bolts, and finally it had a cam retainer plate bolt that had backed off and the cam sprocket was grinding on it for self-clearance.

Rings rotate. It really doesn't matter what orientation you put them in.

 

[Orpedcrow]

I get better gas mileage out of my 97 5.7 4l60e ecsb (lowered 2wd) then I do my 2012 5.3 6l80e tahoe (lifted 4wd). But apples and oranges are both fruit right?

 

[xXxPARAGONxXx]

Thank you all for your opinions. It really firms up the decision. I am sticking with the 350. Now to decide if I should have it rebuilt or say "F it" and attempt it myself.

1. New crate engine and sell the used one.
2. Rebuilt by machine shop.
3. Rebuilt by you.

I guess you can do the teardown and take the heads and block to the machine shop. That would save you labor cost.

 

[Erik the Awful]

My buddy's GMT900 was so sluggish towing that I thought something was wrong with it. It turns out the problem is that it has a 5.3. I'd stick with the 350.

618 Syndicate and User_name mentioned diesel swaps, but unless you tow all the time I wouldn't go diesel. With the premium on diesel engines, diesel fuel, and the higher maintenance costs, the return on investment is poor.

If you DIY with no upgrades, you can put bearings and a gasket and ring set in your truck for under $200. Be methodical. Be tedious. It sounds like you haven't rebuilt an engine before, so plan on it being down for a month or longer. Stay motivated and keep making daily progress until it's done.

 

[JOHNGAAA1]

5.7 L31 Brand new crate motor is the way to go !!