Q-jet with dual capacity accelerator pump
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| − | + | The question came up on what- if anything- is required to use a late model NON CCC/NON electronic Q-jet carb that has the dual capacity accelerator pump. Because these carbs are often mistaken for being full electronic/CCC-type feedback carbs, many who have them either don't know what they have, or if they do they don't know whether they can be used as-is or not. | |
| − | [[Image: DUAL_CAPACITY_ACCELERATOR_PUMP_Q-JET_1985.jpg|300px|thumb|left|Arrow points to Dual Capacity Accelerator Pump plug; circled is where the TPS plug ''would be'' on an electronic or computer controlled Q-jet. The TPS plug '''must be absent''' for a Q-jet carb to be used without a computer.]] | + | [[Image: DUAL_CAPACITY_ACCELERATOR_PUMP_Q-JET_1985.jpg|300px|thumb|left|Arrow points to Dual Capacity Accelerator Pump plug; circled is where the TPS plug ''would be'' on an electronic or computer controlled Q-jet. The TPS plug '''must be absent''' for a Q-jet carb to be used on the street without a computer, however the feedback type Q-jet can be used in race only applications by removing the metering rods and changing the size of the primary jets.]] |
[[File:Qjet with CCC.jpg|300px|thumb|left|1981-up Q-jet with CCC emissions/computer control]] | [[File:Qjet with CCC.jpg|300px|thumb|left|1981-up Q-jet with CCC emissions/computer control]] | ||
| − | + | The dual capacity accelerator pump carbs can be ID'd by their solenoid plug mounted on the passenger side top front of the airhorn/carb top, along w/the LACK of a plug for the TPS (throttle position sensor) that's present on electronic feedback-type Q-jets used during the same years on vehicles using the "CCC" system. The carb number will be '''17085''' or '''17086'''. The 6th number will be 1, 2, 4, or 5. The 7th number will be 0, 1, or 2. If the final digit is an even number it sometimes denote an automatic transmission application, odd for manual. | |
These NON CCC/NON electronic dual capacity accelerator pump Q-jet carbs are found on 1985-'86 GM trucks and vans, and have desirable features- adjustable top-accessed APT, electric choke, correct linkage geometry for OD transmission TV cable, large 800 cfm casting, and generally less use/abuse/rebuilds on them than carbs from the '60s and '70s. | These NON CCC/NON electronic dual capacity accelerator pump Q-jet carbs are found on 1985-'86 GM trucks and vans, and have desirable features- adjustable top-accessed APT, electric choke, correct linkage geometry for OD transmission TV cable, large 800 cfm casting, and generally less use/abuse/rebuilds on them than carbs from the '60s and '70s. | ||
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| − | + | In cases where a large pump shot is needed, like with big cams, single plane intakes and/or heavy or high geared vehicles, an interesting idea would be to set the accelerator pump up with the larger pump shot volume needed for best acceleration when in the default mode. Then with the solenoid activated have a reduced shot volume for the street. The accelerator pump position could be selected using a simple toggle switch. | |
[[Category:Engine]] | [[Category:Engine]] | ||
[[Category:Carburetors]] | [[Category:Carburetors]] | ||
[[Category:Good articles]] | [[Category:Good articles]] | ||
[[Category:GM]] | [[Category:GM]] | ||
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