LS vs Vortec Swap vs Basic Upgrades - Cost Factors

[DoubleDingo]

As @77 K20 has stated, cold days are not vortec-friendly. I have similar issues when it's cold out, but I am running the stock air cleaner, etc. The only thing I changed was the heads and the intake, and then later the cam to a muscle car grind cam that doesn't have any more lift than the stock vortecs can take, and that engine runs very strong. Although the heads and intake are technically GM, and I guess the cam is too because they ran it in factory engines, everything else is factory GM from 1981 that came on the truck. If you went that route (Your Plan C), you'd be out money for two cylinder heads, an intake manifold, and a cam, so maybe $1,000. A weekend to swap it in, and smiles on your face from there on out from the increased power generated and money saved, and not having to tune this, tweek that.

 

[Doppleganger]

As @77 K20 has stated, cold days are not vortec-friendly. I have similar issues when it's cold out, but I am running the stock air cleaner, etc. The only thing I changed was the heads and the intake, and then later the cam to a muscle car grind cam that doesn't have any more lift than the stock vortecs can take, and that engine runs very strong. Although the heads and intake are technically GM, and I guess the cam is too because they ran it in factory engines, everything else is factory GM from 1981 that came on the truck. If you went that route (Your Plan C), you'd be out money for two cylinder heads, an intake manifold, and a cam, so maybe $1,000. A weekend to swap it in, and smiles on your face from there on out from the increased power generated and money saved, and not having to tune this, tweek that.

More I think on it (and count my ducets), this is probably where I'm headed. Would still like to swap out the TH400 for a 4l80e also.

I have a k20 and completed the swap last year(lq4) Started out I was just going to use the motor the way it was. Looked very clean, came out of a low mile wreck. Last minute decision was made to open it up to be sure. Well it was toast. Some water got into from sitting out side and needed a rebuild. I ended up putting a cam in, added new 243 heads and headers. I got around 6k in the motor, another 3000k for the swap stuff. Having said that, I am very happy with it. Makes tons of lower and reliable. These are Canadian dollars so around 6-7k US....

Eventually this is where I'll be - if not with this truck, then the next one. Your install is one of the cleanest - nicest I've seen.

How did you manage the dual tanks with an LS? I've heard that can be fun.

 

[DoubleDingo]

You'll be happy with the improved power. It's well above what these engines made back in the day from the factory. 4L80E, or 3.73's with the correct tire size. @Frankenchevy is getting good mileage on his new vortec setup.

 

[77 K20]

I know you posted about this issue a few years ago, but what air cleaner are you using? It looks like you have exhaust manifolds and not headers. The stock Thermac unit with the heat stove and riser intact to suck in warmed air might help. Not as proximal as the actual crossover, but I’d say it’s the next best thing.

I have just an open element air filter. I thought about the heat stove as I still have my stock air cleaner but have the corvette ram horn manifolds and not the stock manifolds.

 

[77 K20]

I was thinking you are full of **** when I started reading your post. I have a 350/ Vortec heads, the Edelbrock manifold and 1406 carb. It runs great and fires instantly. As I read thru your novel, I admit you make valid points and seem to have done your research.
I'm convinced your on to something. I live in SW Az and our cold days rarely dip into the 40's, so I can't speak from experience.
I'm interested in that heat crossover bypass thing under the plenum. Can you explain more in how the coolant flows? If it comes out if the hose you added, where does it come out?

I work a 12 hour graveyard shift up here so the truck has to run in the coldest time of day during the winter. It can get to -24 degrees up here.

The bypass starts in the threaded hole in the water jacket under the thermostat. This allows coolant to bypass the thermostat then goes under the carb then comes out the other side and is plumbed to the return on the water pump. This circulates the engine coolant without running it thru the radiator.

Without having this bypass I was getting strange temperature fluctuations with the coolant temp sensor in the head. It would wander up and down every 20 seconds on the highway by something like 30 degrees. Tried another thermostat. Same exact thing. But here was the debate/strange thing. Seems a lot of people have no bypass and swear their temp is rock solid. Don't know. It didn't in my case and in other peoples engines. If it isn't needed then why does Edelbrock mention this about the 7116 manifold:

An external water bypass boss is machined into the front of the water crossover for use on 1996 and later Vortec production engines.

And GM had this to say about my crate engine:

Any small block engine, regardless of year, that uses Vortec heads, will require an external coolant bypass line from the intake manifold to the 5/8" hose nipple on the water pump (passenger’s side). Suggested routing is from the 3/8 NPSF boss on intake manifold to the water pump.

 

[Camar068]

A LS swap, on a 4x4, with all new everything just cuz... Is going to add up to more than the truck is worth.

Agree, don't do everything new. But the difference between the two stock 350's I've had in mine and the LS are night and day.

Before it was a 4x4 chevy 350 square with 3.08 gears......lug lug lug here around the hills/mountains of Kentucky.

Now (even before the change to 3.73 gears) is night and day. If I want to go, I can make it go.....and really make it go if I like.

From 8-9 MPG to 14-16 'pending how much I'm having fun with it (no burn outs, but when I take off from a light or get on the interstate....grandpa fell out the bed lol). Passing, not a question if you have enough time or not...make it happen. You won't need a half a mile visual to get by someone.

Before the swap I only drove it when needed and ran weekend trips to the store in the wifes car (nissan sentra). Now I can't go a day without driving it. It's just so enjoyable to drive.

I say this and I haven't even put it on a dyno for a good tune. I expect mpg and my enjoyment of driving it to go up when I do that.

 

[1987 GMC Jimmy]

I have just an open element air filter. I thought about the heat stove as I still have my stock air cleaner but have the corvette ram horn manifolds and not the stock manifolds.

You could rig something up and order you a riser tube. It probably wouldn’t win a beauty contest, but it would be functional, and if it didn’t make any difference, just get rid of it.

 

[4WDKC]

More I think on it (and count my ducets), this is probably where I'm headed. Would still like to swap out the TH400 for a 4l80e also.

4L80e requires either a computer or manual valve body. If you decide to use and ecm it only make sense to do the ls swap as you can get the ecm for the engine and trans combination is stock form.