Now remember I drill these holes the same diameter as the very thin tube so I you have burred hole, bent tube, dirty tube you’re screwed. Be clean. I only tube one head at a time so I get a piece of cardboard and lay down 1.250 inches of JBWeld and 1.250 inches of hardner. Mix and apply small amount (1inch) to one tube at a time. I then put a 1/2 bolt and washer on the head bolt hole tubing and with a plastic mallet drive it home from the head deck side carefully and wipe off excess epoxy with brake clean after each install. Same with pushrod tubing but I use 1/2 bolt and washer. Check out pictures