[ambmech1]

1970 ys 400. Mild cam, Headers, quadrajet with cast iron intake.
Just before putting the car away this past fall I had an issue after starting it. Ran very rough like missing a few cylinders. Pulled the plugs and found 1,7,4, and 6 with the ground electrode bent over and touching the center electrode. No mechanical damage noticed. Other 4 plugs were fine and burning normal. Light tan color. Put new plugs in and it's fine. No noise and running strong and smooth. A little research and it may be a detonation issue? Being a dual plane intake is one side of my carb malfunctioning? Anyone ever run into this? Seems to run fine now but I'm worried it could happen again with more serious consequences.
Thanks in advance,
Joe.