Idles fine - runs great when I mash on it - stutters/stumbles with a little throttle

[jhv48]

Before you start replacing things, do the following:

(Make sure your timing and advance is spot on first, before any changes.)

1. Adjust both float levels to the base of the sight plug (assuming you have a Holley). Test drive.

2. Make sure accellerator pump is squirting immediately when the throttle is moved. Test again.

3. Try opening the idle air screws an additional 1/4 turn (richening) from their current position. Test drive.

[elmariachi]

Originally Posted by jhv48

Before you start replacing things, do the following:
(Make sure your timing and advance is spot on first, before any changes.)
1. Adjust both float levels to the base of the sight plug (assuming you have a Holley). Test drive.
2. Make sure accellerator pump is squirting immediately when the throttle is moved. Test again.
3. Try opening the idle air screws an additional 1/4 turn (richening) from their current position. Test drive.

X2 on all counts.

Plus check idle vacuum and install correct power valve accordingly. A tip-in stumble is almost always a temporary lean condition unless you get black smoke, then its likely rich because of too much PV.

Jim