Originally Posted by JasonL
Quick question, Looking for spark plug advise and gap.
Motor: 355, 9:1 cr, 492 heads with 2.02/1.60, performer intake, holley 670, comp cams 268HE cam.
Thanks in advance
The 492 heads are the 1970 LT1 heads. You can use AC R45 for street driving. These heads oridinally used AC R44 but they are no longer made. The AC R43 is used for a colder plug when racing. A Champion RJ12YC can be used also. Gap is .035 for these plugs. BTW do not use any AC R45TS plugs if the pistons have domes. The S stands for extended tip and will hit the top of the domed pistons on 11.0+ compression motors.