[draven]

I currently have a Mighty demon 750 w/ mech. secondaries.. My question is wether or not this is going to be enough carb for 12 psi of boost or should I go ahead and get a 4500 1050? I originally got the 750 because I want the truck to be atleast somewhat streetable, and I thought a 1050 was a little large.
Specs are:
Supercharged 383
6" Eagle forged rods
3.750" Eagle forged crank
JE Premium forged pistons (8.7:1 C/R)
Jegs 220cc 2.10/1.60 64cc heads,
Crane supercharger cam Adv. Duration: 286°/294°
Gross Lift: .525'/.543''
Crane Roller lifters,
Jegs 1.5 roller rockers,
Edelbrock super victor manifold,
VORTECH V-7 YSi-TRIM supercharger,

1/2 ton pick up with 4.10 gears, th350 w/ 3500 stall. Also can anyone guesstimate what this should run in the 1/4 with around a 3800 lbs truck?

Thanks all

 

[Tech @ BG]

Carburetor too Small?

Draven,

You’ve put together a good-looking combination. A 750 Mighty Demon may be a touch small for your combination; we probably would have gone with an 825. A 1050 is probably going to be too much with only a 3500 Stall Speed. If you loosened the converter up a 1000-RPM or so you may be able to get away with the bigger carburetor, but at that point you’ll run out of camshaft. That cam is designed to go to about 6500 RPM, with a maximum of 10 lbs of boost. As far as overall performance, and drivability you should be extremely happy with the 750. If you’re looking at getting the absolute best ET out of the truck going to an 825 Mighty Demon, or a 975 Race Demon would get you there with the rest of your pieces. Overall I’d stay with what you have.

 

[draven]

Thanks for the reply, much appreciated

I think I'll stick with the 750 and try it out for now. Noone has any estimates on what my truck should run in the 1/4 with this setup?

 

[camaroman7d]

Tech @ BG,
I have been pondering this and to me a 750 CFM carb on a blown 383 engine making 12lbs of boost would be a LOT on the small side.

Since this is a blow thru not a draw through, is that where the difference comes in? I have not played with a blow thru set-up before so I am trying to pick your brain a bit.

I am assuming with a blow through set up the car is actually going to flow and meter much more than 750CFM, correct?

Royce

 

[Tech @ BG]

Royce,

Yes, and no… There are many things to think about when you’re building a combination. On Draven’s combination for example he stated running 12lbs of boost. This is going to be pushing it for a combination like this to be able to actually use, and see a noticeable difference. The cam design is max’d out at about 6500 Per Crane, and is not recommended to be used with anything over 10 lbs of boost. The vehicle is heavy, and the converter is not extremely loose. Those were the factors that lead to our recommendation.

As far as actual airflow or CFM it is entirely up to the combination. Airflow is based upon the engine itself. The “CFM” numbers we rate the carburetors at are an average, or median number if they were installed on an application we would have recommended it on. As an example Draven’s 750 Mighty Demon will flow 933 CFM at 1.5” hg vacuum below it. Meaning that if on his engine there was that much vacuum below the carburetor it would flow that much, more vacuum = more CFM, less vacuum = less CFM.