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.
This is the seven main bearing...
This is the seven main bearing 200ci six-cylinder block. Most 200 blocks are seven main bearing, with the exception of its first year, 1963, where 200ci sixes had the 144/170ci four main bearing block. Ford redesigned the lightweight sixes to seven main bearings to reduce noise, vibration, and harshness. Four main bearing blocks can be identified by three freeze plugs. The seven main bearing block has five.
McLearran Motorsports of Tucson,...
McLearran Motorsports of Tucson, Arizona, builds the fastest Ford sixes in the country. They use cylinder head and main cap studs for extraordinary strength and security.
Rebuilds should always include...
Rebuilds should always include hardened exhaust valve seats along with intake manifold clean up and port work to improve performance. These are good stealthy mods no one can see.
Installed correctly (meaning...
Installed correctly (meaning water passages at the rear), Fel-Pro Print-O-Seal head gaskets are your best bet against a blown head gasket. Make sure your machine shop checks deck trueness and gives it a shave during the machining process. Ditto for the cylinder head.
JGM Performance Engineering...
JGM Performance Engineering uses Viton valve seals instead of umbrella or Teflon. Viton seals offer unequaled durability on street and strip engines.
You can go one of two ways...
You can go one of two ways with stock six-cylinder rocker shaft assemblies--adjustable rockers and cup pushrods or nonadjustable and round-tip pushrods. The nonadjustables were designed for hydraulic lifters, which means you need a specific pushrod length. Adjustables are intended for mechanical lifters.
Cam selection is dictated...
Cam selection is dictated by how you intend to use the engine. Daily drivers don't need radical cams. Instead, they need a cam that delivers low- to mid-range torque for drivability and a smooth idle.
Another item often overlooked...
Another item often overlooked is engine blueprinting. Every camshaft should be degreed to determine real specs versus cam card numbers. Combustion chambers should be cc'd. Volume above each piston at bottom dead center should be checked. Rings should be dressed. Clearances should be checked everywhere.
Rear main seals should have...
Rear main seals should have their gaps staggered away from the main cap to block parting lines. Sealer should be used sparingly.