For a 7AFE (cold engine measurements)
Clearances should be:
Intake 0.15 – 0.25 mm (0.006 – 0.010 in.)
Exhaust 0.25 – 0.35 mm (0.010 – 0.014 in.)
Too tight, and you'll burn the valves up (they don't close properly) and aggressive cam wear - too loose, and you'll get excessive valve seat wear, noisy valvetrain, and loss of power. I'd set them close, but not on the minimum spec - then recheck in 10K-15K miles or so to see if they have settled in any. If you don't feel confident of this measurement, or don't want to open her up again to check - then set all clearances to the dead center of the range - 0.080" intake, 0.012" exhaust.
A homemade wedge may not be able to get enough localized leverage in there to push down the valve lifter to allow you to pull the shim out. You could do it with a wedge and force it down, but you also have a good chance to damage the camshaft - not worth the risk. Should be able to "rent" the tool for a nominal cost or even free, if you put down a deposit at most retail autopart stores.
Need a micrometer to measure the shim thickness, don't want to guess here. Same as the valve tool, should be able to rent or borrow a micrometer from somewhere. Shims, you can sort of cheat by swapping thicker shims to where clearances are too big, thinner shims where clearances are too tight. Or you can price out a set of new shims (ie, all your valve clearances are too tight) - if you shop around, you can get them pretty cheap.
