I have a few questions, I had a ls1 camaro bought parts for the engine cam, rockers, heads (243 casting number). I then needed a truck so I sold the camaro and bought a 99 silverado new style off my grandpa. Now I no longer need a truck but like the ability it has but I want a little more out of it and with 280k I wanna rebuild the motor. I have a 5.3 engine low miles that was free so I got it (pulled myself from the running vehicle). Will all these parts fit? I was told yes with no problems at all but just want to be sure. I'm not looking for the fastest truck on the block but just a little more get up and go. I plan on doing long tube headers at time of engine install and then a tune. Is there anything else I should look for before I start the install? I will be replacing timing chain and oil pump while its apart just for reassurance. Thanks for any help James

 

its my understanding that pretty much every part is interchangeable between 4.8 to 5.3 to 6.0 as far as the LS family is concerned, at least thats what wikipedia says if u search "LS engine". I wanted to do the same thing to my truck so I did the mods that are in my signature. just did a cam swap on sat, i get my tune next tuesday. Supposedly I should get around 75-100 horse more after the tune, or so ive been told anyways. not sure you will want to put that camaro cam in ur truck though, maybe a Z06 cam and springs. Not sure about those heads either but i also dont know much about the difference in the different LS heads (i have 862 on mine). hoped this helps or at least points u in the right direction

 

They are heads off of a corvette, or I was told they were anyway. They were a good deal so I got them and been sitting. The cam Is a slp cam I don't remember the exact specs but I will look them up tonight and post them. I think it was .590 lift that's all I remember.

 

You will need to mill the heads to get the compression ratio back up. I have 799's (same as 243) and has them milled 0.022" to get the same compression ratio as stock. The cam and rockers will drop right in, although a cam for a 5.7L will be "bigger" on a 5.3L.

 

I would be ok with a bigger cam to be honest lol I'll have the heads milled some but I was also thinking maybe a dome piston to up it a little bit. Would bigger injectors be necessary? No forced induction planned for the truck but I don't know what the factory ones are capable of and don't want to have any surprises causing me to take things apart again. Thanks for the help, looking for the cam specs still as well which pushrods would people recommend?

 

If you are going to replace the pistons you might as well punch out the new bore to a 5.7 spec. That way you gain a few more cubes for free since you're replacing the pistons anyway. Another way to do it is find some good used LS1 or LS6 piston/rods. Usually see them all day long for <150.00 a set. Just make sure to re-balance if you use the truck crank with LS1/6 rods and pistons.

Mike

 

Would a ls1 rotating assembly be a good budget mod? verse like a after market crank assembly? Or a ls2? My dad asked if it'd help bump it up a little if we could get a deal on a used set up.

 

The crank and rods are effectively the same on a 5.3, 5.7, 6.0 so you won't gain anything. Same crank stroke, Same rod length. all use different piston size's.

You can Overbore to LS1 spec if the block is good enough. But it should be checked out before doing so. If you want to bump the compression during your rebuild and don't want to overbore that much, order 4.8L pistons. They have the same pin height and same bore size as the 5.3L but there a flat top instead of the dished piston like the 5.3L.

FWIW the 5.7L pistons are also a flat top.

With 799 or 243 heads and the 4.8 pistons you will be close to 9.9:1 compression depending on if you leave the heads stock or need to mill them ever so lightly to flatten them out.

Gm built two 5.3L engines this way with an aluminum block called an LM4 and the L33.

And with a Larger cam especially in the .570- .590 lift like you were talking about, you should run larger injectors as the OEM ones will probably be maxed out.

 

Yes, if you get the chance and it's a decent deal, also get the crank from an LS1 or LS6. Those will have the gun drilled rod journals. They are just as strong but you wouldn't need to rebalance the rotating assebmbly like you would if you ran the LS1 rod/piston on a truck crank. FWIW, the stock cranks in the trucks and LS1/6 are very strong. You would be hard pressed to push the limits of one. Really the only reason you'd want to go aftermarket crank is if you planned to stroke it for even more cubes. But at that point you're having to buy new rods/pistons for the longer stroke.

Mike

 

Your first post says you got a low mileage 5.3 motor. If it is still in good condition and is not burning oil, I would just use that short block. This would be the cheapest and easiest way to go.

If you were rebuilding the old motor, I'd say bore it out to 5.7 size and find a LS1 rotating assembly.

Yes, 243 heads and LS1 valve train parts will fit a 5.3 truck motor. Whether you should use the cam you already have depends on the specs. If it's not too big, go for it. Make sure you install valve springs to match the lift. Replacing the timing chain and oil pump is good insurance. Might want to replace the plastic lifter trays too.