I have a '96 K1500 with a 5.0L V8 Vortec 305 in it. I was considering making some performance upgrades to it such as new headers, air intake, exhaust, etc, when a gentleman at PepBoys suggested that I just swap out the 305 for a 5.7L Vortec 350. He said that all the bolts and connections should be the same so it should be a very easy change to make. He also said I can definitely find one for under $1000 and should be able to sell my 305 for around $400-$500.

I have to say that I've often wondered if I could upgrade to a 5.7L, but this almost sounds too good to be true. Any thoughts on whether or not this can be done as easy and cheap as it sounds? Anyone out there who has done it and can provide some pointers?

Thanks everyone,
TC

 

it is the same motor different bore. all the differences are on the inside of the block. you could do that but for $1000 you can just juice up the 305 you have. It is a Vortec so the intake and the heads are already ported. But you can replace the camshaft and exhaust manifold and measure your power difference there.

 

RacerX,
That was the original plan and I'm still totally open to it. But at the same time if I could put in the 350 and then juice that up? Man... Haha, so that's where I'm at right now.
I think if I can find a way to get the 305 over 300hp I'll just go that route, but I think the 350 would be sick.

TC

 

well, a K&N filter that say can give you 75hp. Low flow exhaust systems can help too.

 

i love my truck it has a 5.7L 350 vortec but dropping a new motor is never very easy unless you have a full on shop. id just juice up that 305 though they have great lifespans and if you find a 5.7 for under 1000 bucks its more than likely been used and you dont want some random persons motor. run what you got till it goes then get a 5.7 thats what i would do

 

Just saw your post and have to say I'm pretty much in the same position your in. I have a 1998 sierra with the vortec 305 and it's bone stock. Well I did put on an air filter and removed the top to the filter box taking it up to about 400 hp. I have been thinking about rebuilding my 5.0, swapping it out for a 5.7, or maybe going with a big block swap from like a 3500. I have decided to do bolt on parts that I know will swap over to a 5.7 if I ever decide to do the swap. Our cam is advertised having .414/.428 lift with stock 1.5 rockers. I'm planning on swapping in some 1.6 self aligning rockers that should bring total lift to .441/.456. From my research stock springs should be okay up to about .470 or so lift. I have single exhaust and it looks like 3" but the wye pipe is small so was thinking about doing Headers, wye piping and keeping the stock 3". Read the id tag in the glove box to determine your rear gear ratio. If you have anything less then a 3.73 I'de change it out to at least a 3.73 or lower depending on your wheel/tire combo and what kind'a driving you do. The junk yard is full of gov lock rear ends. I have no experience with them but alot of people trash talk them. After that I'de think about doing a program upgrade. From what I have heard I don't think you can buy a good tuner unless you have a 99 or newer but alot of people talk about places you can send yours off to and have it re tuned. Good luck and post often like I said i'm in the same boat as you and would love to know the progress!

 

if you do swap to a 5.7 vortec, yes everything will bolt up and be the same but you would need to get the ecm reprogrammed to run a 350. if you leave the ecm the way it is, the 350 will run like crap and run lean. then you'd be back to a gas guzzling version of the 305

 

I myself have the '98 5.0L vortec, and I can assure you that removing the lid on the airbox and installing an aftermarket filter will not create a 165 hp gain.

 

get rid of all the electronic bull**** and run a carbed stroker motor

 

Old threads are old for a reason, generally speaking they should stay that way.


As for your comment, some states that is no longer legal. Doing that would fail the inspection instantly, I know this for fact because I live in one such state, all vehicles 96 and newer are required to be plugged in to the computer and all that electronic bull**** has to be working properly.