Quadrajet Accelerator Pump Volume
Thread Starter
Instructor
Joined: May 2005
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Quadrajet Accelerator Pump Volume
Can the volume of fuel supplied by the accelerator pump be adjusted?
I have a wideband O2 sensor and the accelerator pump shot is causing a rich condition, especially at lower RPM.
Can the volume be reduced?
I have a 1977 with original carb # 17057203.
comments are appreciated.
I have a wideband O2 sensor and the accelerator pump shot is causing a rich condition, especially at lower RPM.
Can the volume be reduced?
I have a 1977 with original carb # 17057203.
comments are appreciated.
Racer
Joined: Apr 2006
Posts: 477
Likes: 43
From: Millbrae California
You can put the rod in the outer hole to shorten the stroke or use a different pump length. there are several different lengths of accelerator pumps that can be used for more or less pump volume the shorter the pump the more the stroke. the rochester #s for pumps are 17074111 for the shortest followed by 17074115, 17074104 (the 104 is the most common #) then 17074108 is one of the longest (less volume). not all of these #s are still avalible from rochester but any good carb shop should carry replacements for these #s.
Henry @ olescarb
Henry @ olescarb
Tech Contributor
Joined: Aug 1999
Posts: 14,382
Likes: 6,402
From: At my Bar drinking and wrenching in Lafayette Colorado
For obvious reasons, the accel pump is intended to cause a momentary rich condition. Unless it's actually causing a rich-induced stumble or black smoke out the tailpipe, you may not have a problem. How rich is the "rich condition?" If you're in the 11.5:1 - 13:1 range at the moment of the pump shot, with no stumble, I don't think you're out of whack.
Lars
Lars
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Instructor
Joined: May 2005
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Thanks for the replies.
IT does stumble if the RPM's are low (>2000) and I floor it quickly.
The a/f ratio can go to 10:1 when I floor it quickly at around 2500 RPM and there is no stumbling. If I slowly roll into WOT, the motor runs great. I'm very happy with it.
Idle is 12.8:1
Cruise is 14.5:1
WOT is 12:1
My main jets are stock #77, primary rods are stock.
Second rods are stock and have been filed to smaller tip diameter.
Motor has stock bottom end
Dart SS 165 Heads
Comp Cams CS XE262H-10
Shorty 1-5/8 headers
IT does stumble if the RPM's are low (>2000) and I floor it quickly.
The a/f ratio can go to 10:1 when I floor it quickly at around 2500 RPM and there is no stumbling. If I slowly roll into WOT, the motor runs great. I'm very happy with it.
Idle is 12.8:1
Cruise is 14.5:1
WOT is 12:1
My main jets are stock #77, primary rods are stock.
Second rods are stock and have been filed to smaller tip diameter.
Motor has stock bottom end
Dart SS 165 Heads
Comp Cams CS XE262H-10
Shorty 1-5/8 headers
