Help with Zl1 lid fittings Cadillac CTSV Forum
Don39t cut off the fittings, bit drill them out with a 5/8quot drill, then work up to 3/4quot. At some point, the fittings will probably pull out and give a nice clean hole. Even if it doesn39t, you want to get them to about 3/4quot diameter, then tap for 1/2quot npt, not 3/4quot. It39s actually a lot bigger than 1/2quot diameter.