This front view shows how...
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...
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...
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.