No matter if you are talking...
No matter if you are talking about the 4.6- or the 5.4-liter versions, Ford's Four-Valve modular engines are technological beasts capable of making big power. Degreeing in the camshafts, however, can leave you scratching your head if you don't know the tricks.
When Ford debuted the modular engine family in the early '90s, the overhead cam V-8 was quite a technological advancement compared to the cam-in-block small-block that had been around for decades. But, the Two-Valve layout doesn't work as well with the engine's smaller 100mm bore spacing. The cylinder heads just couldn't pull in enough air for high-performance applications.
That changed with the birth of the Four-Valve head in 1993. Even though they are slightly smaller, the increased curtain area of two intake valves in each combustion chamber significantly increases how well the engine can breathe, and performance as a result is also greatly improved. In naturally aspirated form, the same block with Two-Valve versus Four-Valve heads jumps from 260 hp to over 300!
The foundation for this build...
The foundation for this build is a 5.4 iron block from a Lincoln Navigator, but the process is the same with any modular engine fitted with Four-Valve cylinder heads. As you can see here, the cams have already been placed in their bores with the caps on top, and the heads are (obviously) on the block.
So it's no wonder speed freaks and sprocketheads love the Four-Valve modular in their Mustangs. It's even the foundation for Ford's fantastic supercharged Shelby GT500 with 500 hp and 480 lb-ft of torque. So despite the complexity of an extra set of valves-and the rest of the valvetrain that comes with it-there is definitely an advantage of going with four valves per cylinder in this application versus two.
A downside of the Four-Valve cylinder heads is it can be tricky to properly degree in the camshafts. We are talking four camshafts, four different timing chains, four tensioners, and seven sprockets (counting the crank sprocket). Worse yet, Ford doesn't build any adjustability into the system! That might be excusable if the cams always arrived spot-on from the factory, but in different engine builds we've found cam timing in stock engines can be off by several degrees. That's like leaving horsepower on the showroom floor.
One quick tip in case you...
One quick tip in case you are installing new cams before we get on to the degreeing part: If you are installing new cams, make sure they do not rub the cam caps anywhere. Also, always make sure the caps go back on in the same spot they came from. Just like main caps that secure the crank in the block, the cam caps aren't interchangeable. Moving caps around will change the clearance between the cam and the housing bore. Some cams will wind up too loose while others will wind up too tight.
Degreeing your cams is the process of making sure your camshaft is correctly positioned relative to the crankshaft. In plain English, this means the cam opens the valves when the pistons are in the correct positions in the cylinders. Although cam timing is normally good when the timing set is installed as directed, cam-timing errors can crop up unexpectedly because of machining errors with the timing set, the cylinder heads, the block or even the camshafts themselves. No matter what engine you are working with, you should always take the time to degree in the cams any time you are building a new engine, installing new cams in an existing engine, or doing any other work that requires you to pull the timing assembly off the engine. Heck, if you have a Four-Valve engine in your Mustang, it might be a good idea to degree the cams just to make sure you aren't giving up any horsepower from a setup that came improperly degreed in from the factory.
Just be aware that degreeing in the camshafts on your Four-Valve Modular motor is a bit more complex that what you might have seen before on a Two- or Three-Valve modular engine, or even a cam-in-block push-rod engine. To do the job correctly requires a few specialty tools and a lot of patience.
To get the full scoop, we traveled to the shops of KT Engine Development in Concord, North Carolina, where engine builder Craig Hibdon was completing the build on a Four-Valve that had been bored and stroked to 351 ci. Even though this is a new build, the process is the same even if you are working on an engine still in your car.
As you can see here, the oil...
As you can see here, the oil pump has to be installed before the crank timing sprocket. The first cylinder is the front-right corner (the right side if you are sitting in the driver's seat). Ford's cylinder numbering for the modular engines has cylinders 1-4 on the right and 5-8 on the left. You can get close to TDC when the crank keyway is pointed toward the center of the number-one combustion chamber.
The Four-Valve heads use four...
The Four-Valve heads use four different timing chains to power the system and four chain tensioners to keep everything in check. This is the tensioner that keeps the short chain connecting the intake and exhaust cam on each head tight. It is nearly impossible to get the chains on with the tensioners activated, so push the lock in, squeeze the tensioner closed and use the end of a paper clip to lock it in place.
Here, you can see one of the...
Here, you can see one of the tensioners bolted in place on the head.
With the tensioner still held...
With the tensioner still held closed, install the two cam sprockets and timing chain connecting the intake and exhaust cams on each head. Each cam has a keyway and each sprocket a key, so they will only go on one way. To be set "straight up" (with the cam timing set at zero advance), both keyways should be pointed straight down. Notice also how the dots at the top of the cam sprockets must also match up with the colored links on the chain to help you get everything lined up properly.
The intake cams are closest...
The intake cams are closest to the center, both use a large bolt and cap to secure the cam sprocket to the cam.
On each of the long chains...
On each of the long chains connecting the crank to the exhaust cams on a 5.4 block, there should be three dark (or otherwise marked) links: one alone and two side-by-side on the other side of the chain. The single dark link should be lined up with the mark on the crank sprocket. On a 4.6 block, the chain is shorter and there are only two dark links on the chain. In this case, the dark link should line up with the dots on both sprockets.