Hi all, In the interest of keeping my car stock and also utilizing the potential of my roschester Quadra jet I tried rebuilding it, and somewhere along the way I guess I made a mistake ,but I’m having trouble narrowing this down, I have scan the website for a similar post but haven’t found an answer, after the rebuild I’ll start my car, (completely cold) , and it’ll idle fine for a minute or so, then it’ll jump to what sounds like 2-3k at idle and I can get it to idle down 20 percent of the time by tapping the gas , but the other 80% it’ll just rev a little higher, I have already checked for something blocking the throttle blades open and couldn’t find anything , I’ve also checked for vaccum leaks, and haven’t had any luck, also I got 2 codes once I put my carb back on , code 32 (egr , which has been removed for some time , although the code never came up) and 23 (m.a.t/I.a.t sensor) and I couldn’t even find one that looked similar to mine at any auto parts websites , could either of those be the cause or does it seem like something else? (Sorry for so much text , would rather over explain then under explain) also the car is a 1984 z28 h.o automatic

 

Verify that both pairs of throttle plates are completely closing in their bores. This may require defeating the thermostatic choke and its high idle (stepped) cam, and probably will require backing off the idle stop screw. If the plates are binding in their bores and not fully closing, the attachment screws would need to be loosened slightly to adjust the position of the plates to allow full closure. It is also important to check for play in the throttle shaft, since this can also allow the throttle plates to stick open, and no amount of adjustment in the plate position will remedy this. If the throttle shaft and or bushings have worn, they can be reamed and bushed to restore them to proper size and fit.

Remove the throttle body from the bowl. This will entail removing the bowl cover, linkages, and various assemblies and bits.

Remove the throttle plate springs and secondary lockout pawl.

Carefully remove the throttle plate screws. They are staked, so it will take a lot of patience, a proper fit of the driver, and several applications of lubricant and reversing direction to prevent thread damage.

Note the orientation of the throttle plates and remove them. Slide the throttle shaft out of the throttle body.




Measure the length of the repair bushing and ream the body to the proper depth.





Verify the correct depth of the ream to avoid unnecessarily breaking through the throttle bore side, potentially causing throttle plate binding problems.





Drive the bushing into place.





Finish ream the bushing to the correct throttle shaft diameter.





Reassemble the throttle plates, links, and springs.

This would also be a good time to seal the Welch plugs in the metering wells on the bottom of the bowl. Both the main and secondary metering well plugs on the underside of the main carburetor body are known problem areas. Any fuel leaking there goes directly into the intake and can significantly enrich the mixture, drain the bowl after shut down, and cause flooding and hard starting. These can be cleaned off, peinned closed, and covered with a fuel-resistant epoxy to seal them against fuel leakage.



Clean the areas, make sure the Welch plugs are securely staked in place, and apply a fuel resistant epoxy to seal over the plugs: