Jim Smart
January 25, 2011
Contributers: Classic Inlines Photos By: Classic Inlines

Duraspark For Reliability
In the mid-1970s, Ford introduced Duraspark ignition on all new cars and trucks. Consisting of electronic distributor, high-output ignition coil, and a control module, Duraspark is easy to install and live with. Classic Inlines offers Duraspark ignition from Performance Distributors for six-cylinder enthusiasts. The cool thing about Duraspark is parts availability everywhere. If Duraspark fails, help is as near as the closest auto parts store.

Keep in mind the Duraspark distributor is only for Autolite 1100 carburetors without spark control. Vacuum for the spark advance comes from throttled carburetor vacuum only, never straight off the intake manifold. Manifold vacuum is constant; throttled vacuum happens only when you step on the accelerator.

Duraspark gets its power from non-resistance power right off the ignition switch-a full 12-14 volts-not from resistor wire (pink) that steps power down to nine volts. You can mount the control module just about anywhere, including under the dash if you prefer a stealthy approach. Painless Performance Products offers a Duraspark conversion kit that makes installation a snap.

Building Tips
When it's time to build a six, here are some important points to remember. If you're shopping for a block or rebuildable engine core, check casting numbers. Ford manufactured two basic types of small six-cylinder blocks-four main bearing and seven main bearing. Unless casting numbers and date codes are important to you, you want the seven main bearing block and crankshaft. All 170 and 200ci Mustangs had seven main bearing sixes.

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