Jim Smart
November 1, 2012

No Unimportant Details

Sometimes, we get so caught up in the confusion of engine troubleshooting that we miss important details. We swap carburetors, change ignition points, adjust timing--yet fail to notice the obvious. What about proper choke adjustment when the engine is cold, with a steady pull-off as the engine warms? Is there a healthy accelerator pump shot when you work the throttle? Is PCV valve function what it should be? If you have ignition points, is the gap correct? Are contacts pitted? Does your Mustang have the correct ignition coil? Have you examined the distributor cap and rotor for cracks and proper continuity? Do your ignition wires pass the resistance test? Is your fuel pump long in the tooth and not delivering adequate pressure and volume? What about the fuel filter? Even if it seems irrelevant, check it.

Though the nimble Ford six presents its share of tuning and performance challenges, it doesn't have to be a poor performer. If you believe in this engine, there's plenty you can do to get its performance back on the beam. Your greatest friend in engine tuning is the desire to troubleshoot. There are no freak occurrences nor is there magic, just physical facts. If you cover the bases step by step and pay close attention to detail, you can super-tune your Mustang six and wind up with a reliable powerplant that will give you a lot of driving pleasure for years to come.

Help For Classic Carburetors

Last year, our hobby suffered the unfortunate loss of Jon Enyeart and, as a result, his Pony Carburetors. We are gradually becoming familiar with other classic carburetor rebuilders in the industry. In Pittsburg, California, Recarbco performs concours restorations on vintage carburetors of all types--Autolite, Motorcraft, Rochester, Holley, Carter, Stromberg, Edelbrock, Zenith, and a host of others. Kurt Praxl has opened his own carburetor restoration shop in Western New York as KP Carbs/Carbontooters. Kurt was trained and mentored by the late Jon Enyeart when Pony Carburetors was located in Western New York. Kurt's work is outstanding and on a par with what you would expect from Pony Carburetors.

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Stealth Mod

We keep beating the PerTronix Ignitor drum, but the darned thing works so well it's a no brainer if you drive your Mustang. PerTronix introduced the Ignitor more than two decades ago and changed the world for those of us who grew tired of fooling with ignition points. The Ignitor is super compact and hides inside your Load-O-Matic or Dual-Advance distributor. And if you bury the Ignitor's wires in heat shrink, this thing defies detection.

Once installed and properly gapped, the Ignitor never requires service or adjustment. Count on replacing your distributor cap and rotor when you change spark plugs while giving the Ignitor a quick once over. Your Load-O-Matic gets a #1266 Ignitor or #91266 Ignitor II. If you have a Dual Advance distributor, order the #1261 Ignitor or #91261 Ignitor II. If you decide to stay with ignition points, don't do it on the cheap. Opt for a Motorcraft or NAPA tune-up kit with heavy-duty points with phenolic rubbing block and vented contacts. Go with a cap and rotor with brass terminals.

Is Spark Knock Harmful?

Ignition timing is not only important to power and fuel economy, but also engine health. If you're running too much timing (advanced), your engine is at risk for spark knock or detonation--that rattling sound you hear under hard acceleration. Light pinging isn't always harmful, but any pinging is unacceptable.

Spark knock typically occurs when fuel ignites prematurely on the compression/ignition stroke. It can be caused by a red-hot piece of carbon or early ignition timing. It can also be caused by combustion chamber dynamics, such as the 351C-2V with its open chambers and poor quench, or a lean air/fuel mixture. You want the optimum balance of good timing coupled with air/fuel mixture in order to keep combustion temperatures conservative. Detonation can be considered a more violent form of spark knock with opposing flash points in the chamber coupled with an ugly head-on collision mid-chamber. Spark knock and detonation act violently on the piston dome, wrist pin, and rod journal.

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22 Some performance issues speak for themselves, like this fuel filter and rubber hoses, which are a fire hazard when positioned over a hot exhaust manifold. What's more, you are at risk for vapor lock and no start while hot. Fuel lines should be hard lined between the pump and carburetor where possible, with the fuel filter located away from a hot manifold.