A car we are working on, a 1985 olds with the 307 V8 with q-jet carb. it has developed a miss at idle. I replaced the spark plugs and wires with no difference. Compression checked all cylinders, they were between 150-155psi. I put adpaters on the distributor cap (HEI) terminals to short out the cylinders one by one. Each cylinder that was shorted caused the tach to drop 150-200rpms, except for number 4. that cylinder had no drop, no difference in rpms... Apparently thats the bad cylinder.

So how can everything be good, but have a dead cylinderat number 4??:(

Have you put a plug or a screwdriver on the end of the wire to make sure it is sparking? Check the plug itself on cyl #4 and see if it firing. If no spark at the wire, then work your way back. Check the wire, cap, rotor etc.

If you are getting spark and all is good you need to look for fuel/air issues.

Thanks for the reply. I forgot to mention that there is spark at the plug.

any thoughts about fuel air issues? we dont understand how there can be good compression but have a issue like that?

Try swapping plugs first (move plug #4 to #1 and #1 plug to #4) see what happens there...I've seen a plug that fires in the open not fire under compression before.
Other than that, you say you have compression and it is obviously getting fuel to the other 7 cylinders since you note the test you did (rpm drop grounding out the cap)