1953-1960 Classic Car Engines Troubleshooting Guide: Backfire

The text for this Guide originally appeared in the 23rd edition of Motor's Repair Manual, published in 1960 and copyrighted by Motor Information Systems, and is used with their permission.

Things to Look For:

Backfiring is a subdued explosion in the intake manifold. Causes are:

1. Lean mixture (often due to dirt or water in fuel).
2. Engine cold and choke too lean
3. Leaky or sticking intake valve or weak or broken intake valve spring.
4. Leakage of current across distributor cap may cause backfire by enabling spark to occur in a cylinder which is on its intake stroke. Two mixed-up spark plug wires may also cause this trouble.
5. Popping back is synonymous with backfire.

The Complete Guide to Troubleshooting 1953-1960 Era American Classic Car Engines