Just an FYI. There's been more a few folks that when fuel system troubleshooting, have discovered the throttle plate either loose or completely off the shaft due to the two mounting screws backing out and getting sucked into the cyl's. ( due to a poor rebuild job no doubt).
Some didn't case any damage and just exited through the exhaust where some others either embedded into the piston and/or damaged the cyl it was in.
I can recall reading of it at least 10 times.
Looks like it's a calculated gamble. Course plastic is much softer than metal screws....
You could try to to let the starter spin the engine over (with the coil wire disconnected) to see if compression will push it out the plug hole. I haven't read back enough to see if this was mentioned btw..
Good luck
Dave
while I did mention your suggestions early on I neglected (yeah right) to mention my own verification of your readings back when Terry Bradshaw was the best QB ever.
Those carb nuts do indeed pass through and a couple small marks were left in the chamber.
Now I haven't tried this on my GMC but I know some spark plugs are the same size as a 3/8" male threaded air fitting... Got Air?
Hook up air to that cyl and start it. No fire forced air..
