When we go back to the box and the circle, consider the bottom of the box line, point number 6, as the effective exhaust closing point for Cam #1. That value will be used for the X-axis-the exhaust axis. Therefore, point 6 represents 60 degrees. For Cam #1, #2, and #6, the exhaust valve is going to close at 60 degrees because all are on the X-axis.
Now, come to the Y-axis at point number 8-that is going to be 80 degrees and it is where the intake valve is going to close for Cam #1, #4, and #8. So, now if we stay with that axis and go back down to the corner of the box where the diagonal comes across, that becomes 73 degrees; the point where Cam #7 and Cam #5 would come across would be 75 degrees. Then we have 80 degrees and, correspondingly, 85 degrees for Cam #3 and #9, and 87 degrees for Cam #2.
Going back to the X-axis, for the exhaust it goes 53 degrees, 55 degrees, 60 degrees, 65, and 67.
The baseline cam, Cam #1, has a 310/330-degree duration on a 105-degree centerline with the intake closing at 80 degrees and exhaust closing at 60 degrees (See Figure 3). Cam #2 at 12 o'clock now has a 317-degree intake, because, though we're keeping the opening at the same point, we're increasing the duration of that intake event by seven degrees, going up to 87 total. So that intake closing becomes 87 degrees for Cam #2. Remember, it's a 317-degree intake; the exhaust stays the same, with a 60-degree closing, making it a 317/330 degrees duration cam.That moves the intake centerline to 108.5 degrees and keeps the exhaust at 105 degrees. The rest is pretty much self-explanatory. As you go around the circle, Cam #3 would be a 315/335 and so on.
What you end up with are nine camshafts to be dyno tested. You start with Cam #1 and measure the area under the curve and continue to run each cam. At the end of the test, you go back and retest Cam #1 to make you sure you can close the loop. That's the only way you can successfully run a test series like that, because you never know what's happening to the engine during the tests. If you want to find out, you come back to the first test to close the loop, and as long as it's plus or minus a percent, you're cool.
When you've compiled all the information, you take the area numbers and compare them. Starting with Cam #1, let's say the number is 425; you write that down by number 1. Let's say the number for Cam #3 is 430 and the number for Cam #7 is 420. You go up to Cam #9 and it's maybe 420, you go down to Cam #5 and it's 420.
So looking at this, you find that the direction you should go is Cam #3 because it has the most area. So that becomes the center of your next circle. Ultimately, the best number is going to come up at the center of the circle. That's the camshaft that the engine likes for the criteria that has been established. It's following a trend and then further fine-tuning it. It's really simple to run a test based on one variable, but you can't do it that way. The engine doesn't look at that; it looks at both intake and exhaust. You have to run a series of tests that are closely monitored and measured. The engine will tell you what it likes and what it doesn't like. I don't know what they're doing today to get the kind of numbers they're getting, but I'm sure it's something similar to this.
HPP: That is absolutely brilliant. What a great process.
Nell: I looked at that when Jeff was doing them and thought, "That's pretty damn smart! [laughs] And that way, there's never any question in your mind. Once you're done with that, you can say, "OK, in this configuration, that's it." In SCCA Trans Am it was really easy because you had one four-barrel carburetor, that was it. They told you what carb you could use. NASCAR is the same way. The only variable you have in NASCAR is the restrictor plate engine. Then you might have to run this whole series over to find the right camshaft.
So that's it-the inside scoop on how Jeff Young and Tom Nell worked their way to the camshaft they ultimately used. It was a General Kinetics solid-lifter grind with 300/310 degrees advertised duration, 0.500/0.500-inch lift, and was ground on 105-degree centerlines. It allowed the little 303 to develop in excess of 456 hp, with a powerband of 5,000-8,000 rpm and a conservative redline of 8,200 rpm. Those who said the engine was a dog were most likely referring to the R/A-V version and never saw it in action in the one race that it was allowed, the 1970 season opener at Laguna Seca. It was indeed a very strong runner.
After that, the short-deck configuration was outlawed, as the production minimum of 1,000 was never realized. Only 25 short-deck 303s were ever built. T/G Racing continued using Pontiac V-8s for the 1970 season, though they were larger, heavier 400 Ram Air IVs destroked with a Moldex crankshaft that used a 2.84-inch stroke, 7.08-inch rods, and 3-inch mains. That combo was used in the Grey Ghost for the 1971 season. It's really too bad that the 303 short-deck Ram Air IV never had a fair shot in SCCA Trans Am. It could have had the opportunity to rewrite the history of Pontiac in the series that inspired the hottest of all Firebirds.
Special thanks to Tom Nell and Tom Vaught for their help with the preparation of this article.