91redchevy

iTrader: (5)

What brand and what size are most of you running on your genIII conversion.
I'm getting conflicting info on what I should run. Don't want to over-carb it
but don't want to choke it either. (LS6 crate)

Darracq

iTrader: (1)

I think a 750 would be good. Thats what i am going to run.

stealth71

iTrader: (15)

What are your HP estimates and any mods to the motor? These will help decide carb size. The right carb for a stock LS1 is not necessarily the right carb for a H/C 450rwhp motor.

NemeSS

iTrader: (127)

have made 500+ rwhp with a rebuilt 750 holley dp
just larger jets and power valve,
engine is trex,stock ls6 head, 6.0 lq9, with vic. jr intake

bygblok

iTrader: (4)

I bought a 750 mighty demon for mine. I was "told" it would be great for the 6.0. I know guys that run bigger AND smaller thoug(ok, waaay faster too).

91redchevy

iTrader: (5)

I was thinking around a 750 would be good. It is a stock LS6 crate engine. Some of the
carb calculators I used said a good 650 would carry me up to 6800rpm @ 100%
volumetric efficiency and I know n.a. I'll only be about 90-94% efficient. I know an 800
would be too big. Thanks for the replies, keep'em coming.

P.S.
I'm running a performer rpm dual plane manifold.

Darracq

iTrader: (1)

I really like the 750 vac I ran one into the mid 10s at 130 in my old nova. Vac sec will only use what it needs. If you have a lot of stall then a dp might work better.

6L.IROC-Z

iTrader: (6)

750 demon jetted down a little has done great for me. read sig for mods.
are you running headers or manifolds?

S10slepper

AED eliminator 650 it has a 850 base plate and flows like 720
it was desinged for 34x'' motors . i turn mine 7200

PRAY HRD

iTrader: (119)

IMO, i think a Speed Demon 650 would do you pretty well with elec choke & vac secondaries. check out part #1282010VE. they advertise them for mild 302-427 engines. that's a big range, but the 346 is right in the middle pretty much and it's easy to overcarb.


personally, i've been thinking about going carb and if i do, i'll do my engine mods at the same time. on paper, i'd like to run the TSP PRC-1 heads with comp valve job, T-Rex cam, Vic Jr, and probably a Mighty Demon 750. i'm also considering a Speed Demon 750 w/vac. secondaries which seems more streetable, but i'm not sure how it would do with the T-Rex since it's lightly over the adv. duration @ .050" max Demon recommends for that carb. oh, and Demon only seems to advertise mechanical secondaries for manual tranny's, but i don't know why. any input?

PRAY HRD

iTrader: (119)

if you're interested in a Demon carb, check out this easy selection guide and then call them on it for final input.....

http://www.jegs.com/instructions/132/Demon.html

hope that helps.

91redchevy

iTrader: (5)

Good info guys. I really like the features of the edelbrock thunder AVS carbs. The guy on
the tech line said to use the 800. They only make it in a 650 or 800. I looked up their
crate engine packages and they use the 800 on their 420h.p. smallblock so it might work
'cause thats about where I'll be at with mine.

chris-m

I recently went through the tech help with Demon and put in all the details of the car for approx 400-430bhp spec (flywheel) on an ls1, with mild cam, came out at 750cfm.

PRAY HRD

iTrader: (119)

what kind of Demon.....mighty, road, speed, secondaries? if i had to guess, i'd say a "speed" demon with vac secondaries.

caged02

iTrader: (21)

I have a Speed Demon 750 mechanical secondary carb on a LS1 with 232/236 .595/.601 cam and a Victor Jr. It seems a bit much, I had to jet it down 4 sizes front and back and it still seems a bit big. I just got the MSD box put on and working on the tune. What's everybody running for jets in the Demon, or if any other mods done to the carb please list them please.

LQ4Monte

On my new 408 I plan on using either my 725 road demon jr. or rebuild my quick fuel technology race carb. Unfortunately right now the Monte is down for the new drivetrain.(engine, rear, driveshaft).

I've used a bunch of different types of carbs on cars in the past (edelbrock, holley, demon, quadrajet). I know the carb manifoilds are set up for a square bore carb, but a properly tuned/modified quadrajet is a good carb.

The AFB/AVS cars are also pretty good (easy to set up)), but I've never had much luck rebuilding them. Also one of mine came with some pourisity problems causing a major fuel leak. Edelbrock did me good however and I recieved a replacement that evenually was used on several different cars. Heck, it's probably still floating around on a '60 plymouth fury polysphere, somewhere.

Right now my favorite is the demon, but I keep eyeing that fully adjustable QFT race carb on the shelf...

91redchevy

iTrader: (5)

I've done some more research and one of the genI buildups in one of my books was a
355 that turned out 390fwhp at 6000rpm and 425ftlbs of torque on a 625 road demon.
They swapped on a 750 holley and didn't gain any power. I have one new in the box from
another project I'm gonna try out before buying anything else.

chris-m

i've just re-checked my email from them and they actually suggested a 650cfm mighty demon for that application, not a 750, so i got that wrong. For my application they advised mechanical secondaries as its to be a track car.
rgds

holley505

iTrader: (1)

WOW ... what tranny are you running ???

AND do you want a mechanical or a vacuum CARB ??

If you are running a stick you can run a little more CARB...

If you are running an auto... you need to run a 650 smaller carb and vacuum secondaries... unless you you have a good stall and wish to see some strip time?? Then go to DOUBLE PUMPER Like i did.

If you had a LS2 I would thing a 750 VAC would be a good choice.

But with a LS1 or LS6 something smaller would give better performance... it seems most of the guys here jetted down the 750s to keep them from being to RICH.