Carbureted ls

[aod92]

I see that most of you guys that do the swap have f.I. How many of you guys are carbed and how do you like it? I'm picking up a 5.3 this week for my truck. It will be a weekend cruiser, and every once in a while take it to the strip for test and tune. I Want to go carbureted for the simplicity of it. Any big downfalls of going the carb route that I may be overlooking? Thanks guys!

[windmill]

going carb is simple,, just buy the msd stuff tho, you can use the chips they supply or do your own timing table built in,, you also can use the map sensor too. has a 2 step system built in too..
I have a mustang with a 6.0 carb runs good 6.4's on motor 1/8 mile

[aod92]

Originally Posted by windmill

going carb is simple,, just buy the msd stuff tho, you can use the chips they supply or do your own timing table built in,, you also can use the map sensor too. has a 2 step system built in too..
I have a mustang with a 6.0 carb runs good 6.4's on motor 1/8 mile

Msd is definitely the way I'll go. Seems like the easy way to do it!

[crazy longhorn]

No issues carbed...just plug & play!I am sure that I lost a little of the "magic", that the fuelie has, such as mileage/cold driveabilty? As far as power, I do not feel that I lost anything! I did use the edelbrock intake & box, but will agree with the rest of the bunch, that the MSD box has more features to program, if you are racing? For my street cruiser, I don't need to mess with anything but the plug pills? That rock /stock 5.3,(140,000 miles) with nothing but a fresh grind/springs & gaskets, has enough 'smoke' to twist my old truck sideways, with a tap on the loud peddle Longhorn

[dec010974]

hello to all. I have a lq4/th400 with an aftermarket camshaft, springs, and push rods. the problem I have with carbed msd setup is that I don't know how much is left on the table when it comes to tuning/driving my setup. even though it feels fine, I haven't learned the how to set my timing/advance up to go with the camshaft. the engine wont stay crunk with the fuel injection set up. the pcm wont compensate fuel, air, and spark for the aggressive ness of the camshaft. I was told I need to have it tuned prior to me driving it. I hope someone can chime in and tell me where to start. the specs of my cam are
.588I/.588:112centerline:228I/228. the carb I use is holley 750 with vacuum secondary (3310)

[windmill]

how are you in the world using both msd and pcm?

[homemade87]

Originally Posted by dec010974

hello to all. I have a lq4/th400 with an aftermarket camshaft, springs, and push rods. the problem I have with carbed msd setup is that I don't know how much is left on the table when it comes to tuning/driving my setup. even though it feels fine, I haven't learned the how to set my timing/advance up to go with the camshaft. the engine wont stay crunk with the fuel injection set up. the pcm wont compensate fuel, air, and spark for the aggressive ness of the camshaft. I was told I need to have it tuned prior to me driving it. I hope someone can chime in and tell me where to start. the specs of my cam are
.588I/.588:112centerline:228I/228. the carb I use is holley 750 with vacuum secondary (3310)

I have a carbed ls2/ls3 top end and love it . It is a screamer . There is no difference in tuning a carb from one to another . Each engine takes a little different tune from the carb . Your best friend is a air fuel ratio gauge. Just cant get it right with out one . You will be shooting in the dark. As for the msd box . The best way is to learn the program and hook up your lap top so you can custom tune . Also adding a map sensor will help part throttle cruise and also help quality of idle . You can always just use the pills that come with it but you will not get the most from you engine either . ls1tech has a carb section with some sticky's that has some good info to get you started . There is a little more to it because of the msd box but it does the same old stuff as the old school tuning method just in a different way . Take the time to lean it and you will love your carb .

[RatPoweredTruck]

Another advantage to FI, transmission control. I'd leave tuning to the ECM since driving conditions are ever changing. Your engine might last longer too because of lesser rich or lean conditions a carb creates. IMHO.
My 2000 3/4 ton 6.0/4L80e is near 300K miles and still running strong in spite of engine rattle at start up. Transmission is holding up as well.

[BR3W CITY]

Originally Posted by RatPoweredTruck

Another advantage to FI, transmission control. I'd leave tuning to the ECM since driving conditions are ever changing. Your engine might last longer too because of lesser rich or lean conditions a carb creates. IMHO.
My 2000 3/4 ton 6.0/4L80e is near 300K miles and still running strong in spite of engine rattle at start up. Transmission is holding up as well.

Its a 2000, it will always rattle on start at high mileage. As long as you keep her lubed up, that rattle shouldn't be an issue (just make sure its not the timing chain rattling. If it is, change it). If the noise is from the valves, try seafoaming it and see if they quiet down.

[crazy longhorn]

It is my understanding, that it is the pistons that rattle in the LS engines, on a cold start? They have a very short slipper skirt, & will rock in the bores, with anything over 50000-70000 miles. To compound the problem, the stock engines are positive deck, on the pistons? That and a little carbon build on top , can create a problem! My thoughts....that piston knock , is a double knock, when the engine is cold...gone in a few seconds of warm up. both of my trucks have that cold rattle....the 02 has 165000 on the clock, & the 5.3 , in the longhorn has 138000 on the clock. But it is sure a piston knock (in my trucks). Up for discussion.... longhorn

[dec010974]

aod92, br3wcity, ratpoweredtruck, its 2015. Its time to enjoy my truck, the way it was meant to enjoy. Bye bye carburetor, FI is the new plan. I wont be going back, I promise, unless I find a 1931 international pick up truck.

[dec010974]

Its time. FI wild side. A smart guy will be coming next week to tune this puppy's sporadic idling bump stick. everything is done except the final wiring for 12v+ ignition power, 12v+ power ground, and fuel pump relay control. I went through the harness last weekend and found all the needed items in the stock, 5.3 (LM7) harness.

[HemiChallenger71]

Longhorn: The piston slap is pretty well known. My 130k mile 4.8 does it on cold start in cold weather for 30sec. Above 30degrees it doesnt do it. I also run 10w-30. I may try 5w-40 rotella and see if it helps.

For you guys with a carb I have a big favor to ask. Can you measure the overall height from the intake valley to top of the carb? I'm debating on carb or FI for my swap and this will help me make my decision. My hood line is low.

[crazy longhorn]

Originally Posted by HemiChallenger71

Longhorn: The piston slap is pretty well known. My 130k mile 4.8 does it on cold start in cold weather for 30sec. Above 30degrees it doesnt do it. I also run 10w-30. I may try 5w-40 rotella and see if it helps.

For you guys with a carb I have a big favor to ask. Can you measure the overall height from the intake valley to top of the carb? I'm debating on carb or FI for my swap and this will help me make my decision. My hood line is low.

When you say low on the hood line, is it Z-ed, or body dropped? there are some pics of my truck.....probably a page or so down.... longhorn

[HemiChallenger71]

No its going in a '59 chevy bel air.

[crazy longhorn]

Originally Posted by HemiChallenger71

No its going in a '59 chevy bel air.

Gotcha....sound like a very cool ride also! I can get out manyana, & measure....you want from the valley plate , to the filter mount on the carb? I will say that the truck intake (LS), stands pretty tall, as does the edelbrock intake /carb , on the LS? The shortest intake that you can run is an LS-1, on the gen III ....longhorn

[HemiChallenger71]

Originally Posted by crazy longhorn

Gotcha....sound like a very cool ride also! I can get out manyana, & measure....you want from the valley plate , to the filter mount on the carb? I will say that the truck intake (LS), stands pretty tall, as does the edelbrock intake /carb , on the LS? The shortest intake that you can run is an LS-1, on the gen III ....longhorn

Any measurement would help. Valley plate to carb flange, valley plate to top of carb etc. I'm having a hard time figuring out how much taller a carb an intake would be over the truck intake.

I have measurements for a regular SBC in an x-frame (buddys car) and I believe the LS is approximatley 1" taller.
A carb'ed sbc fits great under the stock hood (duh they came from the factory). If the LS with a carb comes close to the sbc I will go carb because its easier and cheaper for me. I have a lot of experience with carbs. If i stay FI its going to be a lot more expensive by the time i have a dyno tune done etc. I HAVE to keep the factory hood so thats my limitation.

[crazy longhorn]

Originally Posted by HemiChallenger71

Any measurement would help. Valley plate to carb flange, valley plate to top of carb etc. I'm having a hard time figuring out how much taller a carb an intake would be over the truck intake.

I have measurements for a regular SBC in an x-frame (buddys car) and I believe the LS is approximatley 1" taller.
A carb'ed sbc fits great under the stock hood (duh they came from the factory). If the LS with a carb comes close to the sbc I will go carb because its easier and cheaper for me. I have a lot of experience with carbs. If i stay FI its going to be a lot more expensive by the time i have a dyno tune done etc. I HAVE to keep the factory hood so thats my limitation.

You have to love this....colder than he!! in my spot in Illinios...BRR! I have an Edelbrock top(intake/carb), & she measures 8" even, from the valley/straight edge on the carb, right where the AF sits down? You need to add2 3/4-3" clearance, for the air filter(minimum) Also, where that engine sits in your ride, may be different? Got pics on that 59? Longhorn

[HemiChallenger71]

Thanks!

[dec010974]

@ aod92 just to update. Easy as pie.

[dec010974]

To aod92, well it's very simple to run a LSx with a carburetor. Very easy. In my case, my lq4 has a few mods, ported heads, medium sized cam, aftermarket springs and pushrods. With the stock, reflashed pcm(lt1swap.com), the pcm can't properly run my engine. That's where the smart guy comes in. The tuner will read this information from engine through PCM and make changes such to the fuel trims, read data from O2 sensors, adjust timing, idle, and adjust some other stuff I don't know about. Good tuners can make a stock 5.3(lm7), run great. I'm talking 350/hp good. In Miami Florida, I couldn't find that good tuner to make the right adjustments to the carburetor, and adjust the timing curve through the msd box. Remember my lq4 isn't stock. In my case, the carburetor made the motor run, but not great. after I tinkered with it, to get better results, my lack of experience with a carburetor just couldn't get the healthy lq4 to run great. The lq4 booged most of the time and seamed pig rich. In my case it ran ok, but not great. In most cases, once the PCM is tuned & set up from the PCM readings, the info will be saved to the PCM and the engine will run as it was intended too. Great. I just couldn't get there with a carburetor. If you know your around a carburetor, and you are willing to play around with msd box & pills you may get what I missed. I'm very impatient and ready to start enjoying my truck. I want to get everything working as it should so I can enjoy my rat rod. Good luck. If you need help. any help, pm me and I'll help any way I can. Good luck. 2015. Enjoy your truck.

[aod92]

Originally Posted by dec010974

To aod92, well it's very simple to run a LSx with a carburetor. Very easy. In my case, my lq4 has a few mods, ported heads, medium sized cam, aftermarket springs and pushrods. With the stock, reflashed pcm(lt1swap.com), the pcm can't properly run my engine. That's where the smart guy comes in. The tuner will read this information from engine through PCM and make changes such to the fuel trims, read data from O2 sensors, adjust timing, idle, and adjust some other stuff I don't know about. Good tuners can make a stock 5.3(lm7), run great. I'm talking 350/hp good. In Miami Florida, I couldn't find that good tuner to make the right adjustments to the carburetor, and adjust the timing curve through the msd box. Remember my lq4 isn't stock. In my case, the carburetor made the motor run, but not great. after I tinkered with it, to get better results, my lack of experience with a carburetor just couldn't get the health lq4 to run great. The lq4 booged most of the time and seamed pig rich. In my case it ran ok, but not great. In most cases, once the PCM is tuned & set up from the PCM readings, the info will be saved to the PCM and the engine will run as it was intended too. Great. I just couldn't get there with a carburetor. If you know your around a carburetor, and you are willing to play around with msd box & pills you may get what I missed. I'm very impatient and ready to start enjoying my truck. I want to get everything working as it should so I can enjoy my rat rod. Good luck. If you need help. any help, pm me and help any way I can. Good luck. 2015. Enjoy your truck.

Thank you very much!

[Wasted Income]

I just popped in here to say that carb'ing an LS is like giving it brain-damage.

Flame on.

lol

[BR3W CITY]

Originally Posted by Wasted Income

I just popped in here to say that carb'ing an LS is like giving it brain-damage.

Flame on.

lol

I'm a HUGE proponent of self-inflicted brain damage, and even I won't carb an LS.

[HemiChallenger71]

Originally Posted by Wasted Income

I just popped in here to say that carb'ing an LS is like giving it brain-damage.

Flame on.

lol

Agreed, sometimes its just easier though.