Backfiring
'94 Southwind 454 TBI. When climbing hills just before downshift from overdrive when the engine starts "lugging" it sometimes backfires. After downshift it runs "OK". Engine has 41,000 miles and ra...
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Check the timing. Backfire is generally caused by one of two things. Burned valves or timing. Big blocks are hard on timing chain sets. GM in particular should be done pretty regular.
