What's causing my 351 Modified to start backfiring...?

Asked by Bob_351m Jun 24, 2015 at 09:34 AM about the 1979 Ford F-150

Question type: Maintenance & Repair

Recently, my '79 F-150 has begun to backfire and it's getting worse.  It had been running rough so I replaced the plugs, wires, cap and button(?)...  But now, the backfiring...! I know I have the wires in the right order as I replaced them one by one...  Could it be vacuum, timing or other (electrical)...?

5 Answers

Bob_351m answered 8 years ago

Obviously I'm not a seasoned mechanic - but I am mechanically inclined... Is that under the dist. cap also...?

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OJ answered 8 years ago

Is it backfiring through the intake manifold or an afterfire through the exhaust. Since you replaced plugs and wires and distributor parts are you sure you replaced them correctly to the proper cylinder? Is there a chance you moved the distributor slightly, could affect the timing. Hopefully you do not have a bent valve.

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