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Thoughts on a carbed LS?

handloader90

handloader90

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I've got a 6.0 LQ4 that's keeping the factory fuel injection but I want to pickup a 5.3 at some point to mess around with, flat top pistons, cam, springs, maybe get the heads ported and polished or pickup a nice setup of CNC'd heads and I was thinking about doing the carburetor conversion with say a Holley Offroad Truck Avenger.

Yay or nay to carbing an LS?
 
A lot of people do it, and there's nothing wrong with doing so, although usually the whole point of going with an LS is to take advantage of a more modern and advanced engine, with better drivability, emissions, and powerband, and slapping a carb on there negates some of that. In addition, you'll have to get a box to control the coil packs.
 
If I going to an Ls motor and not keeping the EFI, it'd be for an all out purpose built motor. At that point you may as well go with a BBC though to get the bigger cubes and better heads.

With as many people building gen3 stuff and tuning it well enough to be daily driveable, I really don't see the point in going backwards with the induction.
 
Why bother when you can get 450+ hp leaving semi stock induction. If willing to do head work and a cam and lifter swap a good tuner can get even more and still have later model drivability and fuel economy. Seems like a no brainer to me.
 
An LS motor with a carb will cost a lot to buy the ignition and manifold still because of not having a distributor. Most of the deals I have seen are around 650 for those two items and you still need to come up with your carb and some type of electric pump. If you do your own wire harness, even paying for the VATS and ECU program, fuel pump setup, and swap parts, its still going to be close to a break even or perhaps even less depending on how thrifty you are at the boneyard, and in most cases if you have the ECU tuned afterwards it will produce as much power as the carb (within a couple horsepower in many cases) and have way better economy when you are not going WOT.

Consider that though... How often are you really rolling your engine out to 5500 RPM to get that max horsepower vs driving in daily traffic?

I have a 2013 Frontier as my DD and I saw someone in the Fronty forums complaining about wanting more power and it struck me funny that the 4.0 V6 has more rated horsepower than most of the 350 SBC's that were produced in a standard GM truck, ever (around 260 hp and 280 torque for the Frontier) and it still gets 21 mpg (well mine does at least, lol).

I know that has as much to do with the difference in weight, but you just have to make a real list of what you think it is going to cost you to do that swap, and then probably multiply it times 3.
 
You want simple right? With an LS, trying to reinvent the wheel and make it carbed is actually more complicated than just getting the right wiring harness and computer tuning.
 
rjfguitar said:
You want simple right? With an LS, trying to reinvent the wheel and make it carbed is actually more complicated than just getting the right wiring harness and computer tuning.
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This!! This is also a man that can speak for "well enough"......
 
I can also speak for the well enough tuning comment, Injection is the way to go.

If you want simplicity just do a regular ole 350 with a carb that was designed with one anyway.
 
I once thought about slapping a carb on a Gen III engine. I told Larry and he about lost his mind. Now I don't have the venomous hate for carbs that Larry does, but after looking at the numbers for a carbed intake, ignition module and the other goodies already listed I can have FI. I will say I've personally witnessed Larry taking a hammer to a carb just because. It was pretty funny, then he dumped a bunch of screws down the air horn. We scrapped the car later, but he hates carbs that much.

If you got an LS it's the easiest way to go. It did take some convincing to my Dad to even go with the concept of the 5.3. He is old school for sure. His thought is, the swap is still pretty exotic and could prove problematic on the road. Really, the swap itself is becoming the norm. In the last two years the aftermarket has exploded with options to aid in making one fit. Keep it using stock sensors and you'll have available replacement parts at any local parts store.
 
If you have a complete LS it definitely is. I think even if you got just the motor and accessories, and then had to buy the wiring, ecu and smattering of other stuff seperately it probably still is more cost effective to stick with the factory parts....

I started working on a budget spreadsheet, knowing that if I really wanted to pay the money I could just slap a carb on it and hook up a few wires and be done but I'd be sacrificing the economy of the build, plus when I really started looking at the numbers, the carb option just still looked more expensive on paper. I think if was able to score a good lower mile stock 5.3 for a few hundred dollars then yeah but I got a low low mile unit and paid more.

Speaking of which, for now, I am not planning on going inside the motor but I noticed that there is some gray goop around the oil pan, so I was curious, can the oil pan and gasket be changed OK once in a K5 or should I just go ahead and do it out of the truck, and whatever I end up needing to do, are there any other gaskets that have to be changed along with the oil pan gasket?
 
I can't recall if there is more than one gasket involved (like a 350) but I'd definitely do the work on an engine stand. Oil pan to cross member clearance is already enough of an issue that most swaps need a custom cross member. It's tight...
 
handloader90 said:
Ok, was just curious what the general consensus was.
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To me it sounds kinda like upgrading your truck by removing the engine and hitching the front up to a team of draft horses controlled by reigns and a buggy whip. Which, incidentally, you wind up removing the windshield to make room for the reigns.

It works, but it's putting in a large amount of effort to downgrade to an older form of transportation, in a way that is going to play havoc with the control systems already in place. What's the point?
 
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