David Vizard
June 1, 2007

If you followed last month's basic rebuild, you would've seen how we got to a fully rebuilt long-block for $394. This month, the plan is to build a twin of that long-block. The stock components we intend to change are the heads, the intake manifold, the cam, and the rockers.

The cam we intended to use was one of Comp Cam's XE 270 HR Extreme Energy hydraulic rollers. This cam normally comes on a 112 lobe centerline angle (LCA) and is usually run in conjunction with 1.7:1 rockers. In this instance, it was planned that the stock rockers be changed for a set of Comp's budget nonrail 1.6:1 Magnum rockers (PN 1442-16). Because they're a lower ratio, the cam can use a tighter LCA, so our cam was ground on 110 degrees. Why did we use the 1.6:1 Magnums? The fact that our head choice did not accommodate rail rockers was the prime issue, but additionally, we had some left over from a previous dyno test, and that clinched the deal.

The first move for our power upgrade was to strip the previously rebuilt engine down to the short-block; then remove the stock cam in readiness for the Comp Cams cam.

The Extreme Energy cam in conjunction with the 1.6 Magnums does not have so much lift that the depth of the valve notches in the stock pistons cannot be accommodated, but we are making a head change here as well. The heads we intended to use were Edelbrock's Performer RPMs (PN 60259). These have 2.02/1.60-inch valves, and that's a fair amount bigger than the stock valves. As such, the edge of the valve hits the edge of the piston notch, so a fix is needed-other than new pistons. This is where our partner in crime, Dale Sciranko of Custom Performance, comes in. A big part of his business is bolting on parts that make things happen faster for a Mustang.

Sciranko installs big-valve heads onto stock 5.0 bottom ends on a regular basis. To resolve valve clearance issues, he uses a partial cylinder head and a special piston-notching tool that is located in the guides of the partial head. Once the engine is down to the short-block, he can cut suitable valve pockets in less than an hour, even if the engine is still in the car. This was the procedure used here.

Here, University of North Carolina at Charlotte student Nathan Bornitz times in the new cam. Because of the near-stock compression ratio, a relatively short duration high-lift profile was chosen. This maintained cylinder pressure.

After our engine was stripped to the short-block, the stock cam was removed and the Comp grind installed. At this point, a timing check was done. Here we made the decision that if the cam was within +/- 1 degree, we would run with it "as is" because our stock (and nonadjustable) timing-chain assembly was in perfect condition. As events would have it, the cam, which should have gone in with the intake centerline at 106, actually delivered 105, so we were good to go.

Using masking tape, grease, and a vacuum cleaner, Sciranko got the job done without getting metal shavings into the rest of the engine. Once the valve notches were done, the timing cover and pan were installed, and we were ready to deal with the next valvetrain issue.

Anyone who has tried to extract the most power from a near-stock Mustang valvetrain will have undoubtedly fallen foul to the effects of stock roller-lifter collapse. It would be nice to replace the lifters with some high-performance items, but the budget has already gone for a roller cam.

For any application where over-the-nose spring forces are below 350 pounds, the Comp Cams Magnum roller-tipped rockers are a reliable and cost-effective choice.

This being the case, we will have to perform a fix that will allow the stock lifters to do the job of opening and closing the valves without suffering any collapse. The technique here is to turn the stock hydraulic roller lifter into a hybrid solid/hydraulic or a "solidraulic" lifter. The first move is to strip each lifter separately so as not to get the plungers mixed. Once stripped, discard the lifter's preload spring. Also, you will not be using the stock wire retaining clip. Instead replace this with a snap ring (NAPA has these). Next, find some washers (32) that have an outside diameter (OD) less than the body but that fit over the smaller central diameter. Also, the thickness of the washers needs to be such that you can make up a stack between0.100 and 0.110 inch thick. When the lifter is reassembled, it will have a stroke of only 0.010-0.020 inch. This will limit the amount of collapse that can take place. Do not fill the lifters with oil as this will make adjustments more difficult to do later.

The first operation towards making something of the GT-40 intake is to weld up the casting over the top corners of the runners as seen here. This allows the runners to be ported to a much more efficient shape for flow.

Cylinder Heads
We-the University of North Carolina at Charlotte (UNCC) students and your author-scoured various sources of ads for a set of used heads, and though we have seen them advertised in the past, nothing came up when we needed them. This meant going with a new set, and a pair of Edelbrock Performer RPM heads were acquired.

If you're following this build, you will realize that for a low-buck team, this is a big chunk of change even at the discounted price of $1,080 from Jegs. But even in "out of the box" form, our past tests have shown they represent a potentially large chunk of power for the money invested. Featuring 2.02/1.60 valve diameters, 170cc intake ports and 60cc chambers, these heads represent a large increase in airflow over even the pocket ported heads we had for Part 1 of our budget build series.

The only aspect that is not quite where we want it is the compression ratio. With the valve cutouts and the 60cc chambers, our project engine's compression ratio (CR) works out at 9.1:1. This means we can probably run intermediate-grade fuel even while racing. We didn't intend to sweat the issue of a slightly lower CR because Phase 2 for this motor was to port the heads (they port out easily, with excellent results) and use a set of higher-compression pistons. What these heads offer is not only plenty of flow for 302 inches, but also good port velocity and some way-better-than-average swirl.

Just by skinnying down the throttle shaft and knife-edging the butterfly, the flow of the factory throttle body climbed from 495 cfm to 520.

Valvetrain Potential
There's little point in having a good set of heads if the valvetrain is severely lacking in capability. In the past, a cost-effective choice with which to replace the stock rockers has been Comp Cams' stainless Magnum roller rockers. Not only are they near bulletproof, but they also have shown respectable power increases over the stock items. On an engine with mildly ported heads and a slightly hotter-than-stock cam, our dyno tests have shown an 8hp increase at peak and as much as a 16 hp increase at about 700 rpm past peak. These past performances and the low price made the choice of rockers an easy one.

Induction System
The system we ended up with on our engine was the Ford Racing Performance Parts GT-40 setup. Fortunately for us, the guy we bought it from was unimpressed with it and used it for only a week before replacing it with a more effective intake. That's how we got it (plus some other minor bits and pieces) in nearly new condition for $380.

This front view shows how the serpentine belt was routed. When all the brackets for the accessories were cleaned up and painted, the whole setup looked really smart.

The first move to improve this manifold is to weld up the top of each runner having an acute bend in it as shown in the nearby photo. (As an alternative, you can use a good epoxy.) The reason for doing this is that the porting will break into fresh air before a reasonably shaped entrance into the head is achieved if it's not done. With the welding done, the manifold was ported and matched to our Edelbrock heads. This made a big difference in port flow. At 0.450 lift, our bare heads flowed 235 cfm. Positioning the stock GT-40 intake reduced this on average (some ports are better than others) to 195 cfm. After porting, the average flow was 221 cfm.

The next items on the list to attend to were the throttle body and the EGR spacer. The usual deal here is to go to a larger throttle body in an effort to improve flow into the intake manifold. That's a viable route, but it costs money, so we modified the stock one by streamlining the butterfly and cutting the cross-section of the shaft. This resulted in an increase of flow from 495 cfm to 520 cfm. As for the EGR spacer, none of the emission-related aspects of this were going to be needed. All of the protrusions, other than the throttle bracket lugs, were machined off and the holes were plugged with epoxy. It was now only a case of bolting all of the engine's original parts, from manifold face out, back in place.

This McLeod clutch features good holding torque and a low pedal pressure.

Other Stuff
Our engine is now well on the way to completion. An inspection of the original crank damper showed the rubber was separating from the outer hub. It obviously would not be wise to be spinning this at 6,500 rpm, so a new Professional Products damper was installed. After this, the distributor, the injectors, and the upper half of the GT-40 intake were installed.

A word here on the injectors: With the power upgrades made so far, it's anticipated that we are right on the edge of the fuel-delivery capability of the stock 19-pound injectors. Theoretically, they should be good for about 340 hp at 100 percent duty cycle. Whereas that may be OK at the dragstrip, holding them at 100 percent open for any length of time (such as on a road course), it may not be so good for extended life. If the engine proves capable of significantly more than about 340 hp, the plan is to limit rpm so the injectors don't top out. When the budget recovers, we will then consider bigger injectors along with MAF and throttle body upgrades.

With all the unwanted junk removed and the engine bay detailed, our engine looked good enough that convincing most racers we had only $2,289 in it might be a difficult task.

Installing the Engine
Before installing the engine, a new pilot bearing was installed in the back of the crank. Also, a new McLeod high-performance clutch was used. It offered a much lighter pedal function with at least as much torque transmission capability. It was also lighter, which certainly won't hurt anything. Before installing the engine, the engine bay was thoroughly cleaned and detailed. This was a time-consuming job, but the before and after views of the engine bay made it a worthwhile endeavor.

At this point, the show falls into the hands of Sciranko. He's been doing this dyno stuff for so long that he has built up a wealth of minor tuning moves that stack up to useful power gains over what might otherwise be achieved.

In the next issue, we'll deal with dyno tuning our engine, as well as traction and safety mods.