Modified Mustangs & FordsHow To Engine
Ford SOHC Modular V-8 - Mod Squad
Getting to know Ford's SOHC Modular V-8
Reciprocating Parts Cont.
There has always been debate about the integrity of powdered-metal connecting rods common in Modular engines. In more than 22 years of Modular V-8 production from two engine plants, these rods have never been problematic when employed in stock or lightly modified engines. In short, you can hammer the daylights out of them and still have a reliable engine.
The supercharged 2003 4.6L Cobra DOHC engines had steel Manley rods and forged pistons for endurance—one exception is the 2000 Cobra DOHC with forged steel Carillo rods. If you stumble upon an '07-'11 Shelby GT500 donor or crate engine, it will also be fitted with Manley rods. Yet every other Modular including the 3V that arrived in 2004 has been factory fitted with powdered metal connecting rods. Another popular misconception according to author George Reid is that Modular engines all came with forged pistons, which has never been true. From the factory, all Modular engines (except the '03-'04 DOHC 4.6 Cobra), including the 3V and DOHC versions, had high silicon hypereutectic pistons. The beauty of hypereutectic versus forged is expansion properties. Forged pistons yield greater expansion, which calls for a loose cold fit. Cold knock until the engine warms up is often a side effect of the loose fit. The same can be said for hypereutectic pistons in that they tend to knock cold, but warm and expand more quickly than forged.
There are two basic crankshaft types used in all Modular engines—six- and eight-hole nodular iron. The eight-hole cranks are Windsor or high-performance Romeo, according to George Reid. Reid adds that since 1991, when production began, there have been a few basic cranks used in all Modular engines. All are nodular iron. Sean Hyland of Sean Hyland Motorsports, who builds and races a lot of Modular engines annually, told Reid he's never seen anyone break these crankshafts. The nodular iron crank is good for up to 500 horsepower. Given a choice between six-hole and eight-hole, choose the eight-hole flange. There are two crankshaft weights available—heavy and lightweight. The quickest way to identify is the balancing holes in the counterweights. Heavy cranks were made for heavier connecting rods, which first entered service in 1996.
There is the steel eight-hole M-6303-D46 DOHC/Cobra crank you can drop right into the SOHC block. Some minor block modifications may have to be made to prevent block and counterweight interference. If you're building a 5.4L SOHC, there is a steel crank available, M-6303-M54, with an eight-hole flange.
Another closely related issue is the harmonic balancer. There are three basic types for the Modular engine—six-rib for 4.6L, wider six-rib for Cobra/DOHC, and the eight-rib for 5.4L engines. There are also aftermarket balancers for the Modular engine, which tend to follow the six- and eight-rib rule.
Torque To Yield?
Torque to yield is a long-practiced concept designed to prevent over tightening. These fasteners are easily identified by a slight bevel or taper below the bolt head.
Their use calls for tightening them to Ford's specification, then tightening them the suggested additional number of rotational degrees. Torque to yield fasteners are a one-time use fastener—use them once and throw them away. Not all Modular engine fasteners are torque to yield, but cylinder head bolts surely are.