*Poor Throttle Response*

[zippi]

I have a 1971 350 sbc (double hump heads) with a Demon 625 carb setting on an aluminum high rise, headers, nice cam. It runs great but at Idle when I pop the throttle it stumbles. It smells a little rich at the exhaust. What is the easiest way to tune this carb?

[glennsexton]

Do you have this document?

http://documents.holley.com/lit701rev10.pdf

[firebird77clone]

Check the accelerator pump. If there is another setting available which would give a bigger squirt try that. If you're running a vacuum advance check the dapshot.

[techinspector1]

Must disagree with Denny. The aluminum high-rise, dual-plane intake manifold has shown through extensive dyno testing to produce the highest horsepower and torque readings of ANY naturally-aspirated intake manifold being produced today. All it will take, in my opinion, is a little carburetor tuning as offered by Glenn in post #2.
.

[Driver50x]

What is your initial timing set at? Does your distributor have a vacuum advance? I have found that using a vacuum advance, connected to manifold vacuum, really helps throttle response on a mild street engine. Along with proper carburetor tuning of course.

[glennsexton]

"aluminum high rise" That's your problem...

Had to laugh at this one as it reminded me of a friend who years ago put a Torker II manifold and a 750 DP Holley on a stock 283. We lived at over 5,000 feet as well - what a dog. He burned up a lot of clutches before swallowing his pride and admitting he'd made a huge mistake!

That said - I've used my share of Performer RPM, Holley, and Weiand dual-plane manifolds with great success - typically with 650cfm Edelbrocks or my favorite - 750 Quadrajets. Zoom Zoom!!

[zippi]

Thanks for the input guys.

[rumrumm]

An aluminum high rise manifold is a little like saying you have a 3/4 race cam. You either have a dual plane or a single plane intake manifold. Not to be hyper-critical, but a person needs to be specific. It makes a lot of difference.