I'm trying to drill and tap my intake for the 5/8 line from the heater core. I drilled the correct 45/64" pilot hole and I have a 1/2-14 NPT tap, but the pic shows the furthest I can get the damn thing to go. The black mark on the tap is how far it needs to go. Any tips here? I don't want to crack a $400 intake trying to do this. Thanks for any replies.
Edited to add: I have not been using any kind of lubricant or tap wrench. Wonder if these would help...
1968 Impala SS
Last edited by 68WASAGOODYEAR; 05-10-2019 at 11:32 PM.