Thread: need carb tunning suggestions

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First of all bear with me, this is my first time doing this. Here is what I am running: 383 sbc that is internally balanced, Eagle 5140 rods and crank, Kb hypereutectic flat top pistons w/ valve reliefs, 10-1 compression, Comp cam XE274
Product Line: COMP Cams Xtreme Energy Camshafts
Part Type: Camshafts
Cam Style: Hydraulic flat tappet
Basic Operating RPM Range: 1,800-6,000
Intake Duration at 050 inch Lift: 230
Exhaust Duration at 050 inch Lift: 236
Duration at 050 inch Lift: 230 int./236 exh.
Advertised Intake Duration: 274
Advertised Exhaust Duration: 286
Advertised Duration: 274 int./286 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.487 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.490 in.
Valve Lift with Factory Rocker Arm Ratio: 0.487 int./0.490 exh. lift
Lobe Separation (degrees): 110
Intake Valve Lash: 0.000 in.
Exhaust Valve Lash: 0.000 in.
Computer Controlled Compatible: No
Grind Number: CS XE274H-10

Pro topline 72cc aluminum heads w/ angel plugs, crane 1.52 roller tip rockers, Edelebrock RPM air gap intake, Mallory Distributor and a MSD 6A box and plug wires, my trans is a turbo 350 with a 2500-2800 stall.

The Carb I have is a 750 Holley w/ vacuum secondaries and an electric choke, I believe it is the 4160 model. What I need is some info for setting up this carb to run with my engine combo i.e., jet sizes, squirter, cam profile, ect. Right now the engine is running rich and bogs down when you try to rev the engine quickly. The carb was bought used and my buddy rebuilt it and now we just have to tune it. If some more info is needed let me know and I will post it once I get it. I am not expecting the perfect combo from this post, but I would like to be in the ball park with the first changes that I try.

List number on carb is a what? That would help start the info. Did you put a vacuum gauge on it and if so, what did it read at idle?

its a model 4160 list 3310-2, vac was 18" once the idle mix was set. it;'s timed to 11-12 degrees BTDC

check the size of the jets since you got it used i would probably start with 66,s and go from there

First, I believe that you are over carbed. IMHO you don't have enough cam and cubic inches to support a 750. If the stock 72 jets are in the carb I'd drop them to 64's and go from there. What you need is a book such as the one below which will take you step by step on how to tune a Holley.

Be cautious on going too lean too quickly. The boosters and venturi square area needs to stay within a certain range to keep airfuel ratios within a runnable situation.

I agree... should stick close to stock jetting for a start and move from there. Being over-carbed "shouldn't" affect the a/f but the throttle response won't be as crisp... I don't think the 750 on this 383 is overkill but a 650 would probably give better response (though the vac secondaries should help this situation...)

Disclaimer: I've been proven wrong more than I care to admit!

Two cents,

-Chris

Disclaimer: I've been proven wrong more than I care to admit!

Two cents,

-Chris[/QUOTE]

Amen brother....We all have to go thru that once in a while. That's how we learn how not to do it...