Engine delima - advice sought

[Oilbrnr]

Here's the situation; I've got a '77 K5 that I got from the original owner going on three years ago. Sands Chevrolet here in Phoenix put a GoodWrench long block in it in '97. It has about 30k on it, and is consuming oil at a growing rate via the valve guides.

I have a 2007 Silverado 4.8l LSx that needs the alt/ps alum. bracket and and alt/pump. (came from a major driver side wreck, I'm assuming...) Downside, I'm worried that it would strong enough for the K5. Yeah on paper it is very comparable to the old 5.7, but... Also, I'd need to get all the other parts to get it installed, including figuring out what flywheel/clutch combo will work.

Then again, I could try and pick up a decent 454 in running shape and drop it in.

I'm running the stock 3.73 gears and 33's, and it was/will be my DD during the work week. (trying to save the Duramax!)

So rebuild the 350, do the LS swap (with a small V8) or go 454?

[STOCKISH]

Do the LS swap. You will be beyond suprised with that 4.8 For daily driving the 4.8 is a great engine and will do everything you ask of it besides pulling a loaded car trailer really quick. With no emissions and a tune it will put down PLENTY of power for ya!

[PRattenbury]

I guess you have to weigh the cost of installing the 4.8 against the benefit you would have over freshening up the heads on your existing engine. That's what I would do, but I'm a cheap, lazy bastage.

[Oilbrnr]

Originally Posted by PRattenbury

I guess you have to weigh the cost of installing the 4.8 against the benefit you would have over freshening up the heads on your existing engine. That's what I would do, but I'm a cheap, lazy bastage.

Well, me thinks that it also needs some bottom end attention too. If I'm yank'n it, it would get a *decent* rebuild.

72SC, I'm leaning back towards the LS swap. You are not the first to state that the 4.8 with the right tune, is a decent mill. Hope the SM465 is ready for that kinda power!

Look for *Project Peanut Power" in the build section soon.

[Clyde65]

The 4.8 will do fine, I have one in my 65 and as far as power and such, it is lots better than my 350, it gets 20+ MPG on the highway and averages 14.5 in mixed traffic, it also has plenty of power to break the tires loose when I want to show off.

[glock35ipsc]

The 4.8 will be night and day difference from the 350. The question of using the 4.8 wouldn't even pass through my mind, I would just be doing it!

[Oilbrnr]

Well if Bob says to do it, then I guess I better get busy!! Labor day weekend may be spent getting the shop ready to start pull'n the K5 apart.

What is the best way to pick up some of the missing front accessories that I need for the 4.8L? Local junkyards or posting in classifieds here and on LS forums?

[piecesparts]

Things to consider:

*Fuel pump---unless you put on a carb, the fuel pump will have to be electric
*different exhaust, it should clear, but may not
*different motor mounts
* do you get the WHOLE engine---accessories and all
*4.8 truck engine, then the accessories should be in the right place for your truck
*tranny connection--does the new tranny connect to your drivetrain--will oyu have to make a new driveline or spline adapters
*computer setup, are you ready for that type of project
*Do you have the time to install a complete engine and do the extra stuff

[Oilbrnr]

Thanks, but I'm aware of what is involved. I've just been sitting on the fence for too long.

I'm missing the alternator, PS pump, bracket that they mount to, and the DBW pedal (and maybe module that it connects to). Otherwise it is complete AFAIK. Oh and the DS exhaust manifold is gone.

It is a truck motor, and I'll be mounting it to a SM465, so the engine mounts will need to be *flexible* in their adjustments somewhat, as I'm not relocating the rest of the drivetrain!

I've got a big shop, esp. if I pull out the toys, and I do have a two post lift. So the major limitation will be, as usual, $$$.

[piecesparts]

Originally Posted by Oilbrnr

Thanks, but I'm aware of what is involved. I've just been sitting on the fence for too long.

I'm missing the alternator, PS pump, bracket that they mount to, and the DBW pedal (and maybe module that it connects to). Otherwise it is complete AFAIK. Oh and the DS exhaust manifold is gone.

It is a truck motor, and I'll be mounting it to a SM465, so the engine mounts will need to be *flexible* in their adjustments somewhat, as I'm not relocating the rest of the drivetrain!

I've got a big shop, esp. if I pull out the toys, and I do have a two post lift. So the major limitation will be, as usual, $$$.

Keep in mind that your old tranny does not need a lot of the stuff that the newer ones have. So the computer could have the stuff in it to shift the tranny and if it is used with an older style tranny, then you have a computer code to eliminate. A good hacker can do that, but you have to find one.

[Oilbrnr]

Originally Posted by piecesparts

Keep in mind that your old tranny does not need a lot of the stuff that the newer ones have. So the computer could have the stuff in it to shift the tranny and if it is used with an older style tranny, then you have a computer code to eliminate. A good hacker can do that, but you have to find one.

Yeah, I'm pretty sure the SM465 only needs a backup light wire. Even that is negotiable.

OTOH if you mean that the tune has to eliminated the need from feedback from the transmission (auto) then that is a different story. I don't think it does though, other than some sort of accurate speed input. I plan on using a Cable X.