For those running a carb.
For those running a carb. 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)
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)
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.
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.
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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?
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?
Last edited by PRAY HRD; Dec 19, 2006 at 07:54 PM.
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.
http://www.jegs.com/instructions/132/Demon.html
hope that helps.
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.
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.
Originally Posted by 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.
what kind of Demon.....mighty, road, speed, secondaries? if i had to guess, i'd say a "speed" demon with vac secondaries.
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.
Teching In
Joined: Nov 2005
Posts: 27
Likes: 1
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...
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...
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.
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.
TECH Regular
Joined: Oct 2006
Posts: 417
Likes: 1
Originally Posted by PRAY HRD
what kind of Demon.....mighty, road, speed, secondaries? if i had to guess, i'd say a "speed" demon with vac secondaries.
rgds
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.
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.
