E4ME-Broken lean mixture/solenoid screw.

[MCSS]

Hi all:

Last year I acquired a 1988 Monte Carlo SS with the original CCC Quadrajet.  Because the car has spent a LOT of time sitting, I figured the carb could use a rebuild so I bought a clean-looking core from an '87 Camaro off ebay.  I also bought one of Cliff's CCC Q-Jet rebuild kits and the special CCC carb tools.

Last night I decided to tear down the core carb.  Everything went great until I got to the lean mixture screw (the one that secures the MCS plunger).  Using the tiny double-D socket, I began to gently turn the screw.  It turned fine for about a half turn, but then felt tight, so I started alternating 1/8 turn clockwise and counter clockwise.  The screw was turning nicely, until the "head" broke off.  At this point I was just hoping to salvage the main body of the carb, so I grabbed my smallest vice grips to try to remove what was left of the screw.  The screw turned easily for about 2 full turns, then it broke too.

I've been tinkering with cars for almost 20 years and think I have a pretty good feel for when a fastener is about to let go, and I didn't use brute force or try to force the screw.

I realize that at this point this carb is probably scrap and I need another carburetor.  My question is how can I avoid this fiasco in the future?  Is there a trick to getting that screw out?

Thanks in advance for any insight.

[Cliff Ruggles]

Difficult to remove them once they are broken off as the are small and difficult to drill on center.

Those fine metric threads can be difficult at times.  Doesn't take much corrosion on them to lock the screw up and they do twist off pretty easily. 

I always use some Kroil on the stubborn ones and give them some time to soak.......Cliff

[MCSS]

Thanks.  How long do you typically let the Kroil soak?  Hours? Days?

[Cliff Ruggles]

Sometimes overnight if they aren't loosening up.  We also use some heat on fasteners that are really not wanting to come out, but it's difficult in some areas as there are often things around them you don't want to ruin with the propane torch......Cliff