q-jet aneroid cavity insert
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Cruising
Joined: Feb 2014
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q-jet aneroid cavity insert
Hi c3 friends. Congrats to the forum. The question is about a Q-jet # 17057202, i would like to know if it is preferable to have the aneroid cavity insert in or not. Rochester service manual shows not norservice instrument kit worksheet. But one has been installed when the car was built. What the impact if it in or not? The reason of my question is I am trying to fix an many years issue. If I run car at least ½ hour and let sit at least ½ till 1½ hour engine cranks about 15 secondes before running (very rough) at only 500 rpm instead (not flooded). Thanks in advance.
Melting Slicks
Joined: May 2007
Posts: 2,415
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Hi c3 friends. Congrats to the forum. The question is about a Q-jet # 17057202, i would like to know if it is preferable to have the aneroid cavity insert in or not. Rochester service manual shows not norservice instrument kit worksheet. But one has been installed when the car was built. What the impact if it in or not? The reason of my question is I am trying to fix an many years issue. If I run car at least ½ hour and let sit at least ½ till 1½ hour engine cranks about 15 secondes before running (very rough) at only 500 rpm instead (not flooded). Thanks in advance.
Last edited by PAmotorman; Sep 23, 2016 at 02:11 PM.
Team Owner
Joined: Jan 2006
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From: Crossville TN
Either the fuel in your carb is back-flowing to the tank and/or the accelerator pump in your carb is malfunctioning. The latter problem is VERY likely as original seal on the pump shaft was not compatible with ethanol.
First, install a fuel filter in the carb that has a back-flow prevention seal. It is a little black rubber flap at one end of the corrugated filter tube that allows fuel to come in but prevents it from draining out of the carb. If you still have problems after doing that, put a new seal on the accelator pump in your carb (they usually sell the pump shaft/spring/seal as a set). It's pretty easy to do that with carb on the engine; or you can replace it when you do a carb rebuild. If that carb has never been rebuilt, it's time to do so.
First, install a fuel filter in the carb that has a back-flow prevention seal. It is a little black rubber flap at one end of the corrugated filter tube that allows fuel to come in but prevents it from draining out of the carb. If you still have problems after doing that, put a new seal on the accelator pump in your carb (they usually sell the pump shaft/spring/seal as a set). It's pretty easy to do that with carb on the engine; or you can replace it when you do a carb rebuild. If that carb has never been rebuilt, it's time to do so.
Last edited by 7T1vette; Sep 23, 2016 at 03:44 PM.
Tech Contributor
Joined: Aug 1999
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From: At my Bar drinking and wrenching in Lafayette Colorado
Hi c3 friends. Congrats to the forum. The question is about a Q-jet # 17057202, i would like to know if it is preferable to have the aneroid cavity insert in or not. Rochester service manual shows not norservice instrument kit worksheet. But one has been installed when the car was built. What the impact if it in or not? The reason of my question is I am trying to fix an many years issue. If I run car at least ½ hour and let sit at least ½ till 1½ hour engine cranks about 15 secondes before running (very rough) at only 500 rpm instead (not flooded). Thanks in advance.
Lars
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Cruising
Joined: Feb 2014
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Q-jet aneroid cavity insert
Some years used the insert and some did not. The insert only limits the amount of fuel in the bowl for evaporative emissions purposes, and has no function or effect on the carb whatsoever - it's irrelevant if it's there or not, and it has no effect on the problem you describe or on any other carb function. I have an all-original 1978 carb on my workbench right now, and it has no insert. Next to it I have a 1977 and a 1979 carb, both with inserts.
Lars
Lars
