What is the color of #1 plug? oily, white, grey, brown.....
Does the engine make any kind of noisy, lifters ticking?
Does it miss under a load or only at idle?
Can you hear the miss in the exhaust pipe or just feel it?
Is the engine using coolant? Are you loosing coolant out of the radiator?
#1 cylinder is weak around the front of the block where the water pump bolts on, if the head bolt is over tightened, you can crack the block causing coolant leaks.
As for the carburetor, anything wrong with it and all six cylinders will be affected, plus a leaking intake port will affect two cylinders since its a siamese head design. (two cylinder ports for one intake port)
This engine has a hydraulic lifter and cam set up. They don't need any adjustment of the valves. If the cam is going bad, you should hear the loose rocker making noisy. You might pull the valve cover and watch the rockers on #1 just to verify they are lifting as much as the others. With the engine off, grab the valve spring and see if you can move it sideways, pry and push, this will tell you if the valve guide is loose, causing oil usage and fouling the plug.
A simple compression check will tell you a lot about the cylinder as well.
How much blow-by comes out the breathers?
Loose or broken rings will effect how they run.
Joe
