What does it mean when…
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Joined: Oct 2005
Posts: 83
Likes: 0
From: Gummersbach/Germany NRW
What does it mean when…
while driving between 2500 and 3500RPMs and the engine stutters? Also, there is a stumble for about 2 to 3 seconds when I accelerate moderately? The funny thing is if I nail it (Aggressive stomp on the gas pedal) it shortens the stumble to about 1 second and at WOT is goes really well. It also runs beautifully while idling.
It’s a ZZ3 350cid with a four speed manual trans.
Things I have changed since the problem occurred:
Timing completely digitally controlled and set new
Installed new plugs
Installed new plug wires
Swapped carburetors from a 600cfm Edelbrock to a Holley 700 Double pumper
The only change felt is that with the new carb, there is more power. The stumbles and stutters are still there.
The pump actuators have no play so it can’t be that. Also, while idling, when I hit the pump, it gives a shot as it should.
Vat does sis mean???
It’s a ZZ3 350cid with a four speed manual trans.
Things I have changed since the problem occurred:
Timing completely digitally controlled and set new
Installed new plugs
Installed new plug wires
Swapped carburetors from a 600cfm Edelbrock to a Holley 700 Double pumper
The only change felt is that with the new carb, there is more power. The stumbles and stutters are still there.
The pump actuators have no play so it can’t be that. Also, while idling, when I hit the pump, it gives a shot as it should.
Vat does sis mean???
Le Mans Master
Joined: Apr 2000
Posts: 7,562
Likes: 9
From: B'Ville NY
Cruise-In III Veteran
St. Jude Donor '05
Originally Posted by MotorHead
Usually a lean condition, try jetting up the primary and secondary 
Beginning by increasing your jet size 
Go up by 2 steps to see if it improves, then keep going until the stumble goes away (should also be smoother at 2500-3500rpms) 
Burning Brakes
Joined: Jan 2006
Posts: 761
Likes: 0
From: san jose California
Originally Posted by SmokedTires
Beginning by increasing your jet size Go up by 2 steps to see if it improves, then keep going until the stumble goes away (should also be smoother at 2500-3500rpms) yup, i have the same issue, ever since i got my super comps the thing runs outa gas sometimes, it also causes overheating so both of us should really get goin and change those dam jets!!
Le Mans Master
Joined: Apr 2000
Posts: 7,562
Likes: 9
From: B'Ville NY
Cruise-In III Veteran
St. Jude Donor '05
Too lean at idle can cause it to backfire through the carb. Changing the jets should help your driving lean condition. What is meant by going up in jet size is; pull the fuel bowls off your Holley and see what number is stamped on the brass jets that are screwed into the metering blocks, then remove and install jets with a higher number. If you don't have a jet kit, this kit will be very helpful at tuning your carb to get the jets that will work best for your engine.
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