Small Block & Big Block Chevy Specific - How to tune a carb???

alright guys i need some help with tuning my carb. Its Edlebrock 650 cfm, this thing is drinking like there is no tomorrow. I bought my car with it and single exhaust. I bought the flowmaster 80 series and a K@N air filter for the improvement of gas milage but Instead of my gas milage going up it has decreased dramatically. How would tune i this thing where it would still perform really well but not guzzle through a 14 gallon tank in 3 days. Any info would really help. Than'x :)

This guy does some pretty good write-ups on carb tuning. See if this helps at all:

http://www.moparchat.com/forums/showthread.php?t=56571

whats your engine/combo? may can just simply change metering rods? is it fouling plugs if you idle around such as sitting at redlights etc...if you bought your car this way then whoever built it may have the carb set up the way your engine needs it to be

i fixed it the other day, its just a sbc 350 with edlebrock 650 cfm and K@N. I turned the metering rods all the way to the right where it started to die out and then turned it back 1 1/2 turns. I bought the car with it, and it was getting decent gas milage for a 350 then i put headers, flowmaster 80 series and the K@N to increase the gas mileage but it went the other directon.

Ouch... the Carter AFB / Edelbrock stuff is a pain to tune. Is it possible you could pick up a Holley for cheap?

Ben T.

I turned the metering rods all the way to the right where it started to die out and then turned it back 1 1/2 turns.

Explain how exactly you turned the metering rods? You must mean the idle mixture screws on the front of the carb. Glad you got it fixed.

Best way to tune that is to throw it away and put on a Holley... :)

:werd: on the holley. imho a holley is the only way to go for any performance application

Metering rods are a huge pain. I think you're right Joewee350, K.I.T.T. might have been refering to the idle mixture screws that control the amount of air-fuel emulsion the engine sees at idle.

Ben T.

i had an edelbrock and the secondaries somehow got stuck shut...last time ill ever own one. now i have a street demon and i LOVE it. I say make a good investment now and get rid of that thing

Pick up a NICE used holley 600 vacuum secondary. Check ebay for holley p/n 1850. You'll thank yourself.

Ben T.

it had to be the mixture screws, i had the same carb and those are the only screws he couldof turned

But, but, but its shiny!! They don't sell crap, they just manufacture it.

'97bird, what?

Edlecrap is a nice shiny looking carb.

i had an edelbrock and the secondaries somehow got stuck shut...last time ill ever own one. now i have a street demon and i LOVE it. I say make a good investment now and get rid of that thing

Agreed. I'd get myself any used quadra-bog, and rebuild it, before I'd purchase any Edelbrock carburetor....

I was gonna say try turning the idle mixture screws all the way in, then 3 HALF turns out (which would be 1 1/2 turns). That'll pretty much set you a baseline on a holley and you can go from there.


Splatt - you haven't had any problems with your Demon carb having metal shavings, leaking fuel, and/or not holding a tune have you?


There's a reason I ask.

alright guys i need some help with tuning my carb. Its Edlebrock 650 cfm, this thing is drinking like there is no tomorrow. I bought my car with it and single exhaust. I bought the flowmaster 80 series and a K@N air filter for the improvement of gas milage but Instead of my gas milage going up it has decreased dramatically. How would tune i this thing where it would still perform really well but not guzzle through a 14 gallon tank in 3 days. Any info would really help. Than'x :)
The Edelbrock carbs are actually really easy to tune. Edelbrock has a really nice tutorial video available to view online.
http://www.edelbrock.com/automotive_new/misc/tech_center/install/tech_vids.shtml

:werd: on the holley. imho a holley is the only way to go for any performance application

I have a few buddies who run the holly street avengers and they seem very street friendly and easy to tune.