Help, I have "QUADRABOG!" I never had a bit of problem with the original Q-jet, until it started sending "smoke signals"
1984 Chevy Caprice Federal 305. No Thermac (open side air filter housing with K&N filter), no A.I.R., timed by ear to "no ping on load". Otherwise well maintained, stock, 55K miles, new O2 sensor. Accelerator pump appears to be instantly delivering fuel with initial movement.
The original #17084201 Q-jet had a worsening fuel well leak to the point of bumper sooting at idle.
It was replaced with a #17083204, rebuilt by a "national" carburetor shop. Their "customer service" just advises to "take it off and send it back"; other issues not relevant here that cause me to suspect slipshod/defective rebuild.
First, on a cold (open loop), the there's near stalling bog on medium acceleration Yes, I may need even more fine tuning of choke, but this may be relevant to closed loop issue below....
On a warm engine, at about 15 to 20% intended throttle opening there is hesitation/bog/stumble. This happens at mainly but not exclusively at low RPMs, and at approximately 7 inches of vacuum. From a stoplight, or with a gradual acceleration at speed and even cruise control application of throttle, there is a bog, from a "stumble" to a momentary - 1/2 second near complete loss of power. Applying more that 25% throttle, to WOT, eliminates this problem, and a 5-10% "old-lady" start eliminates this, also. It is abrupt, and consistent.
The accelerator pump appears to be working fine, vacuum hose and connections OK and all linkages are free and unbinding.
The second issue is at about 1500 to 2000 RPM, at a steady-to-slight-uphill cruise, there is a "sputtering" or "hunting" feeling - like a weak ignition miss, again maybe at 10 to 15 inches of vacuum, that is frequently noticeable. This would, I understand, be a CCC (closed loop-part throttle) issue, but I suspect that this may be related to the prior issue, and again I never encountered this before.
Also, the carb shop sent, and advised it to be correct, a different air horn gasket. The supplied gasket does not cover the front middle areas as the original one did. Surely this...
I really think it's a primary/secondary transition adjustment - that 7 to 10 inch vacuum period (IMHO) seems to be where this would happen, and the "bog" and "hunting" there is consistent. Again, it's not a RPM or throttle position issue.
I tightened the secondary air valve spring tension another 1/4 turn tighter, in 2 stages. The bogging seemed a little less noticeable with the initial 1/8 turn tighter, but the additional 1/8 turn seems to make it nearly as bad as it was originally. Disabling the EGR seems to make the bogging worse.
I am stumped. Help, please. Thank you!
