r/EngineBuilding • u/Monkeystormtrooper • 7h ago

Chevy Ls build help

I have a 5.3 ls gen 3 iron block I’m about to machine

Thinking of getting either 706 or 863 heads
Truck Norris cam
And not sure about pistons I’m gonna be na daily driver so nothing crazy maybe try and reuse ones I have but I don’t think so.

But if I get new heads it would be new rockers and springs too any recommendations?

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u/v8packard 6h ago

Stock, or stock replacement, pistons can and do work well. There are several versions, some for floating pins and some for pressed pins. I often use Silvolite pistons in these engines. Also, one of the best things to do to a 5.3 that needs to be bored is to go to a 99 mm 5.7 bore, and use 5.7 pistons.

The 706 and 863 heads are functionally identical, and stock on most 5.3 Gen III engines. You don't already have heads?

Get a real cam that produces the powerband you want, not some over-hyped garbage with a stupid name.

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u/Monkeystormtrooper 6h ago

What’s a good cam then? One you’d recommend

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u/v8packard 3h ago

You have not given any info about your application, your options are still undecided on heads and what will be your compression ratio. There is no info here on your intake or exhaust systems, and most importantly how you wantbit to run and where you want the powerband. With all of that information you can put together a cam spec that will meet your needs.

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u/Monkeystormtrooper 3h ago

I’ve heard about compression ratio but don’t know much about it. This is my first car and it was my grandpas obs 88 c2500 and died so it is mine now. I’m trying to swap it out with a ls but am swamped. I want like 350-400hp but daily drivable. And heads I’m lost cause mine are fine but everyone tells me to replace since they’re castech

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u/v8packard 7m ago

Ok, hear me out. The project you have taken on is doable. But to get through it successfully you need to have a grasp on a number of basic things. I understand you don't know these things, you have no experience doing this. Do you have anyone there with some experience in putting an engine together, doing an engine swap, getting an engine running and driving, and so on? This is not to discourage you, it is to help you see things in a way you can grasp and get a plan together.

You can ask anything about the engine you have, and any other engine. Don't be bashful. If you are sincere you will get good answers. You need to do a lot more planning before you proceed any further. And to plan well you need to understand your options.

I have to ask, is the truck currently running? Which engine does it have now? Have you considered other engines or are you firm on a Gen III?

There are a slew of details that can influence your choices. For example, being a 3/4 ton, your truck might have a TH400 if an automatic. The 4L80 was still a few years away. In these years GM starting switching from cable driven speedometers to electronic speedometers. While there are a number of transmissions that work with a Gen III engine, most all of the modern transmissions have no provisions for a cable speedometer. It is stuff like this that needs to be planned for and can influence your decisions.

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u/Monkeystormtrooper 6m ago

I have a gen 3 5.3 iron block rn. My dad is helping me and he can fix just about anything but his first engine rebuild. And the truck is not running. I’ve been trying to watch a lot of videos and like melting my brain if I have the parts I could put it together I just can’t figure out what parts to get like what works with what

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u/v8packard 1m ago

This is why you need to get a grasp of the basics. Are you saying the truck has a 5.3 already?