Powerheads builds plenty of...
Powerheads builds plenty of stroker modulars. This is a Cobra-based stroker crank built by Ford's supplier, Kellogg. Made in the United States and carrying slugs of heavy metal for internal balancing, this is a durable, high-dollar, high-quality answer to stroking the modular. At press time, cast-steel cranks were due from China and are expected to lower rotating assembly costs by $500.
Powerheads takes its name from its complete line of cylinder-head work. The company offers the full spectrum of early- and late-model small-block heads, as well as the current modular fair. It's sort of neat to see old Cleveland castings mingle with the overhead-cam variety.
Here be dragons," printed 15th century cartographers when they didn't know what was on the other side of an ocean, and it might as well be the slogan of small-block Ford enthusiasts when it comes to building modular V-8s. Raised on a steady diet of pushrods, the typical V-8 fan doesn't know a thing about timing two or four camshafts, and it's only natural to be afraid of what you don't know.
What's important about 4.6...
What's important about 4.6 crankshafts is their unusual fillets. Instead of being a gradual rising curve, the fillets are formed by a roller, resulting in a groove. Modular bearings are designed with this groove in mind, and if a modular crank is reground, and ends up with a traditional fillet, the bearings will edge-ride on the fillet unless a chamfer is cut into them. It's something to watch for on any modified or nonstock modular crank.
And, to be honest, there are good reasons to pause. Both the GT and the Cobra modular V-8s are not free-wheeling engines. In other words, if the cams and crankshaft are not correctly timed, the pistons will foul the valves, not to mention your wallet. And, Ford didn't do anyone any favors with its corporate acid trip of mish-mashed modular parts. Learning what parts are what and getting them from a vendor on time can be a trial. And, of course, there are more parts to keep track of, and few of them are inexpensive.
But if you have a modular under your hood, there are good reasons to learn the modular ropes. Once the modular V-8 has been demystified, you'll discover that, in many ways, the modular engine is not trouble, just different.
In fact, argues Ralph Pici at modular engine specialist Powerheads Performance, assembling modular engines is easier than building pushrod small-blocks. After following Ralph through some assembly work, we see what he means. With modular engines, the brainwork is in assembling the cylinder heads, and because enthusiasts normally buy their heads assembled, either new from Ford (PIs, for example) or as assemblies from tuners such as Powerheads, there's nothing to them save for taking the heads out of their shipping boxes.
That leaves the modular short-block assembly, then setting on the heads-another easy job-and, finally, timing the cams and crankshaft while installing the timing chains and associated front-engine dress parts. So setting up the cams is the unusual part. The rest is standard stuff such as screwing on the oil pan, water pump, intake, and so on.
Main Bearing Inserts
Here's one to watch for at the parts counter. Powerheads has determined there are four modular V-8 main-bearing inserts to watch for. Starting from the left in the photo they are as follows.
Clevite 77 MS-2202P. The only Windsor bearing.
Federal-Mogul 7292 MA. This Romeo piece is called a bi-metal bearing, but it actually seems to be an all-aluminum unit. Stock replacement part.
Federal-Mogul 148M. The second Romeo choice for GT engines, it features tri-metal construction. The lower insert is guttered for increased oil flow.
Federal-Mogul 149M. The Four-Valve or Cobra bearing. The lower insert is guttered, and the locating tangs are different.
Powerheads uses the popular...
Powerheads uses the popular Eagle connecting rods in engines up to 650 hp, or maybe a little more. The two lengths seen here are by far the most common. The shorter 5.850-inch piece is used in 5.0 stroker engines. The 5.993-inch part in back is for stock stroke engines. Eagles are about $600 a set from Powerheads.
High-powered modular engines...
High-powered modular engines have been rare, but they are becoming slightly more common. Such engines take the last word in quality parts, and when the customer starts talking 800 hp, then Powerheads reaches for the Manley billet rod seen here behind the usual Eagle. The price on the red, white, and blue Manleys is about $1,200 a set.
Powerheads uses pistons machined...
Powerheads uses pistons machined to its specs on Manley forgings. Two versions are offered-the Competition offering is at right, the Severe Duty is at the left. Powerheads is happy with the Competition pistons up to 600 hp, and is comfy with the Severe Duty units through 750 hp. The difference between them is in the aluminum alloy, not the machining, so they look alike.
Comparing a brand-X modular...
Comparing a brand-X modular aftermarket forging to Powerhead's on the right shows just what tanks the Powerheads pistons are. Besides the thick skirts, Powerhead pistons are extra thick through the pin boss as well. Ralph at Powerheads says he "doesn't care so much about the weight the crank and rod are pushing-the piston has to last. Otherwise, what's the point?"
Windsors use three half-moon-shaped...
Windsors use three half-moon-shaped thrust bearings; Romeos use one half-moon (shown here getting checked for thickness) and one flanged main bearing insert. Occasionally a box of Romeo bearings will contain two of the slim half-moon inserts, but only one is required. If you mic the pair, you might find that one thrust bearing is 0.001 inch thinner than the other, so you could fine-tune the thrust if desired with this "extra" insert. All modular thrust bearings are keyed, so they can only go in one way, with their grooved side facing the crank.
There's nothing terribly different...
There's nothing terribly different about laying a modular crank. All five main bearings are the same grooved-insert style on the block side. The plain bearing inserts go in the caps. A small bit of assembly lube will "glue" the insert thrust bearing to the block. The thrust bearing on the cap is flanged, so it doesn't need any help. Lube the bearings and crank journals with some sort of sticky assembly lube, lay the crank, and move on to the main caps.
All the inserts with open grooves are upper inserts. The plain, or less grooved inserts are lowers. The standard Ford aluminum bearings use a lower insert that is 100 percent plain. The 148M and 149M bearings use lowers that are guttered with a gradually shallower groove on each side. These are Yates-style, for more oil flow at higher rpm. Powerheads says the stock Ford aluminum bearings are best for naturally aspirated engines. They fit the crank beautifully, and often 100,000 mile crankshafts come out looking better than stock because the bearing/journal interface has polished the crank all that time. Forced-induction engines do better with the physically more robust tri-metal (steel shell) bearings. In any case, you'll throw less of a rage when the tangs and materials line up when you go to lay the crank.