Surge and stumble at cruise and low RPM

[DJCarbine]

I took the electric choke off my holley 4160 series carb because its been really warm in chicago.... and I figured the removal of the assembly will aid in air flow.

Now, at low RPMS and at cruising speed I notice a surge and stumble. If I accelerate, it is fine, but if I keep a steady speed or let my foot off, there is a definate stumble/miss/surge.

I plugged the line coming out of the carb that goes to the choke, and that is the only thing that I can figure is causing it. Is this consistant to a vacuum leak? Its really late, and I want to have some ideas on where to look for when I dive into it tomorrow.

Thanks!

[wma]

you may want to look at this http://www.ponycarburetors.com/defau...ors#holley4150
the holley 4160 had a history of this problem to to the fact it was to large for this engine (design Flaw)

[DJCarbine]

The thing is, it ran flawlessly 2 days ago... so I doubt its related to the history of being too big

[mstngjoe]

you may want to look at this http://www.ponycarburetors.com/defau...ors#holley4150
the holley 4160 had a history of this problem to to the fact it was to large for this engine (design Flaw)

#1...There's no mention of a 4160 Holley on the page you linked to. That is the carb in question here.

#2...The assertion that the Holley 4150 "is just too big" for the Boss and Shelby cars is complete sales b.s. in IMO.
Do the symtoms they list for the 4150 occur? Sure they do. But it's not because the carb is too big. It's because the carb needs rebuilding or is not properly tuned.

[mstngjoe]

The thing is, it ran flawlessly 2 days ago... so I doubt its related to the history of being too big

Put it back the way it was before you had the problems. If the problem goes away you have your answer. If not, you've eliminated the possibility and you can go from there.

The symptoms you describe can sometimes be attributed to a lean condition.

[red1970mustang]

If you removed the choke and plugged the vacuum that normally pulls through the electric choke. Then you may just need to readjust the idle mixture.