76 d 100. removed carb and noticed had a screw missing so i replaced it .fear that screw may have fell down the manifold when i picked up carb.i started the truck and heard a ping. i had 2 damaged plugs on inspection. am wonderimg what is the least amount i have to take off head before i can remove the head to see if i can find the screw? thanks in advance

Unless you have way more time than money, I'd be looking at getting an inexpensive videoscope & look into the cylinders via the spark plug holes. One model is the Autel MV208- is has pretty good video images & can save to a mSD card (also has a 90* mirror & a tiny magnet attachments). Prices range $100-150.

Otherwise; drain coolant, disconnect: exhaust pipe, throttle cable, trans kickdown, carb fuel & vac lines/hoses, ignition wires, heater/radiator hoses (including bypass), temp gauge & choke wiring, alternator & mounting bracket (if needed), oil dipstick tube (if needed), A/C compressor (or air-smog pump) & brackets- if needed, manifold to engine brace- if present, valve cover, rocker arm shaft w/ pushrods, lastly headbolts. Bolt a chain to 2 holes on head between manifolds & valve cover, then pick the whole mess up with an engine hoist.

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63 Valiant Wagon
225 - 4 bbl

How would one screw harm two plugs? If it got into one cylinder and damaged that plug I can see that, but how would it get into another cylinder?

What size was it? It is possible if it was a small screw that it passed through and is gone. More likely not!

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6