MattG

I did a search and found very limited posts on Carb'ed LS1s within this forum so I figured I would make a post..

I am currently looking into dropping a Carb'd LS1 into my 1970 Firebird. I am going to be going with a 346ci with forged pistons, stock rods with ARP bolts, stock crankshaft with a set of ported Ls1 castings with stock valves and Patriot gold valvesprings, retainers, etc. The heads flow in the 280-290 range at .600". I believe I am going to go with a camshaft in the low 240s duration with around .610" lift.

I am just wondering what success everyone has had with running the edelbrock intake kit that comes with the MSD ignition for the LS1. This is the route I am probably going to be going.

Do the LS1s respond well to a carb? Should I go single or dual plane intake? The car will be 95% street use, but I do not mind an agressive feeling car at all.

I know in a 4th gen fbody with the oem fuel injection a setup like this would make in the 390rwhp range. I am wondering what type of power at the crank this engine would make with a carb.

Also, what carb have people went with on carb LS1 setup?

Any info would be greatly appreciated as I am trying to plan out this project that I will be doing this winter. The engine is already in the works, its just all the details to work out now!

bygblok

iTrader: (4)

check with TJ about the carb conversion. His third gen car with the carb'd 6.0 is drop dead gorgeous and fast as hell too. The cool part is that it idles in the staging lanes and never gets hot, drives like a stocker but is capable of runs DEEP into the 6 second range in the 1/8. His car is the big reason I decided to do mine. It's a jealousy thing.....striving for perfection like his.

1FSTZ71

iTrader: (11)

Agreed TJ is the man on that but I have experience with it also (researched it when I put the LS1 in my 3rd gen). It works pretty awesome, TJ is running 7.17 in the 1/8 on a cam only 6.0 at 96mph I think. I didn't think he hit 6's yet? Maybe I'm wrong lol. Last time I talked to him though he needed a new converter because the one he had was too loose for nitrous

bygblok

iTrader: (4)

don't let TJ sandbag you Dallas. On a mild shot of spray he's been waaay faster. Yes, I think it's got more in it since it does sound like it's driving through the converter a bit.....or spinning tires a good ways down the track. Check out his time listed on the GCM site. I'm pretty sure it show a couple of #6's. Hey, you wanna build some more headers? I'll give you the car once I get the LS sitting in it......

1FSTZ71

iTrader: (11)

I could do another set. Just let me know whenever. Need to get a set of 3rd gen headers and a set of LS1 flanges from GM. I have all the part numbers still.

Mean Green z28

iTrader: (17)

Did the conversion for a customer last year, came out looking pretty decent. Couple of pics before the final cleanup/bling treatment.

bygblok

iTrader: (4)

man if that thing had draglites on it the thing would be my cars clone!! Thanks for the ideas......

TJ

iTrader: (10)

car might have been blowing through the converter, but after the 1st time at the track with nitrous, i killed 3rd gear.
could have been the tranny.
changed a few things with the converter and went from
6.94 at 102.50 1.6 60ft to
6.67 at 103.51 1.493 60ft.

i still wish it was cleaner, looks all clutttered to me, but its in there and running great, so i dont even pop the hood much.
lifters sure are starting to show signs of wear from me revving it to **** and back all the time.
tick tick tick.
it wont be long.....
thanks for the comments!

TJ

iTrader: (10)

im having great luck with mine. buddy of mine has a similar setup (346) in an s10 and it absolutely flys.
he has been wearing out all the local dragters in the brackets.
i run a 750cfm HP carb (830cfm i guess) but i wish i had a 950. gonna need it for a bigger motor.
for the intake, id go single plane and never look back.
cam that big, you wont see the benefits of the dual plane anyway. its just gonna restrict you on the top side.
good luck!!! sounds nasty.

bygblok

iTrader: (4)

the picture in no way does the setup justice there TJ. Guys, TJ's ride is A1 in anyones book. The guy has his poop together. Oh, and TJ isn't even paying me to say this either!! I can only hope my car will be as nice(maybe not as fast) as his is....... see you at EC tonight TJ. Bring those brackets if you can.....

MattG

Thanks for the info and pics guys!

How is the hood clearance with the carbed ls1? Does the carb sit up pretty high in comparison to other motors? Does anyone know how if the single plane intake is much taller than the dual plane?

I think I am going to get a body shop to cut a hole in my current hood and then I am going to mount a shaker to the inside of it and have the carb sit up inside the shaker with a small air filter on it. That seems be my only option other than run a cowl, which I do not want to do.

I am thinking I may relocate the coils to get them off of the valvecovers. I will probably have a set of sheetmetal valvecovers that I will want to show off.

Here are a couple pics of the car:

TJ

iTrader: (10)

clean car!!!!
both intakes are near the same height as i recall.
its a bit higher[the intake] than a std chevy setup.
i used to be able to run a 4" element on a drop base aircleaner and have about 1/4-1/2 inch of room. i now run a drop base with only a 3" element and its enough to scratch the underside of the hood from vibration.
i dont run a stock hood on my 3rd gen, but it gets you an around-a-bout idea.
good luck.
you got a nice ride to start with.
interior pics ?

93Polo

iTrader: (5)

Matt,

Clean car and after seeing your other rides I am sure it will be a clean install. Good to see you back in the Lsx world

MattG

Thanks man! How have you been?

I am looking very forwrad to having an LSX under the hood of one of my cars again!

My race car seems to have priority over my street car as of late but I am doing my best to make this LSX transplant a reality by spring. I am sure it will take a year or two after that to get the car exactly how I want it with wheels/tires, guages, etc, etc... I have a vision of what I want and now its just a matter of making it happen!

Jmax

Hey I'm curious, what kind of effect does this have on the fuel milage of these engines? If it's not bad it would sure beat trying to get a computer and wiring and all that going in an old car to run one of these engines.

Do they make carb setups for the lt1 also?

MattG

I am sure the MPG with a carbed LS1 isnt near as good as a EFI LS1, but I bet it is still much more respectable than a carbed SBC.

I am not expecting that great of fuel economy from this conversion because I am going to be sticking with the th350 3-speed. I am however going to try out the 3.07 gears that are currently in the car. I expect to rev about 3000rpm at 70mph, which isnt all that bad with an LS1.

TJ

iTrader: (10)

not that it matters, but i get 13mpg.
th350 5000 converter.
ive gotten 18 in the winter being easy with the throttle, but thats no fun.
my car wasnt built to get gas milage.
i have less cam in the 6.0 than i did in my 383sbc. it was horrible 8-10mpg at best.

93Polo

iTrader: (5)

Yes GMPP did have a carb intake for LT1 motors.

Matt,

I sold the FRC and bought a 2500HD with the LQ4 as a tow vehicle in preparation for a track car. Now I'm saving to get a car for HPDEs and track days.

Sounds like you have the Nova running good

Jmax

Wow that's not bad, at least not as bad as I expected. I was knocking around the idea of going carb just to not have to jack with wiring and fuel systems etc, I'm lazy lol. I'll probably do whatevers cheaper though.

Oh and nice car's you guys got there. Makes me want to hurry up and get after my conversion already.

MattG

TJ, what manifold is that on your car? The GMPP?