compression

Hello! I recently did a compression test on my buick 300. I got a decent 120# on all cylinders except the number 1 cylinder which read only 60# and it did not drop after sitting for 30 minutes. Spark plug doesn't show any signs of mechanical damage nor any gas or oil on it. I took the valve...

I am rebuilding a 1927 Roadster with a Buick Nailhead 401. We recently ran a compression test and all but 1 was putting out 150 PSI. 1 was outputting 120 PSI. Any suggestions on what could be the issue? Thanks, new to cars, so sorry if there isn't enough info here.