nobody mention ing coil Ihave msd coil #8253 on my 340 backfired one day stalled got it restared ran poorly started to smoke from tailpipes changed msd box didnt work changed coil was back to normal when it backfired blowed out Intake gsks. your Comp readings are fine I did same ckd .comp readings were 35psi off please try know good coil

Last edited by 340rocks; 02/10/10 10:31 PM.