Join Date: Aug 2008
Location: Saskatchewan, Canada
Re: 302 rough idle, hesitation, backfire through carb.
An IR temp gun reading the exhaust manifold at each cylinder will tell you if they are firing because a non firing cylinder exhaust will read much cooler than a firing one. If the plug is not firing it may be evident by the colour of the plug, it may be dark and wet, showing it is fouling. If you don't have an inline spark tester, but do have a timing light with inductive pick-up, then you could see if the light flashes when moving the pick-up to each plug wire. That is some things for starters, other guys will have many more options for you to consider.
1970 XL, 351W originally 2V, now 4V
670 Street Avenger, Edlebrock Performer intake, Comp XE262H, Flowtech Headers