Jim Smart
February 1, 2001

For several issues now, you've been watching us squeeze more horsepower and torque out of an aging '65 Mustang GT with 289 4V power. During our first installment, we tried tuning tricks with our 289 to see how much power could be gained. We changed the spark plugs, curved the stock ignition, tuned the carburetor, and installed a Pertronix Ignitor retrofit. After a baseline of 128.4 hp and 193.9 lb-ft of torque, we gained 2.9 hp and 3 lb-ft of torque with simple tuning. No horsepower records there but some difference with tuning.

When we installed the Edelbrock Performer RPM manifold and 600-cfm carburetor in our second installment, then retarded the ignition timing, we gained 16.3 hp and 7.4 lb-ft of torque-not bad. From there, things began to look up.

Fuel and Ignition Tuning

You would be amazed at what simple ignition and fuel and exhaust tuning could do for performance. Fuel and ignition tuning involve little, if any, cash outlay. Exhaust tuning can get quite involved but offers the biggest payoff sometimes. We recurved the ignition and rejetted the carburetor for some of our biggest power increases. Tuning the ignition and the fuel systems helped us make the most of our bolt-on experience.

In Part 3, we installed National Parts Depot's Turbo 211/44-inch dual exhaust system and Hedman long-tube headers for another 6 hp and approximately 10 lb-ft of torque. This gave us a total gain of 22.3 hp and 22 lb-ft of torque. Do you notice the pattern here? Horsepower and torque tend to go hand in hand with our modifications. Along with our exhaust system mods, some carburetor tuning tricks gained us yet another 8.5 hp and 9 lb-ft of torque-for a total increase of 30.1 hp and 30.8 lb-ft of twist. Again, horsepower and torque run neck and neck.

So what does all of this teach us? It teaches us that we should always think about engine modifications as a package. Merely bolting on a manifold and a carburetor won't net you those outlandish power promises you've been reading about since high school. To create power effectively, we have to tune and retune-with modifications. And we have to perform modifications as a cohesive package that works well together.

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Dyno Run No. 1
Baseline Test, No Modifications
rpm power torque
3,400 125.5 193.9
3,500 125.7 188.6
3,600 125.9 183.6
3,700 127.2 180.5
3,800 127.1 175.6
3,900 127.1 175.6
4,000 128.0 186.0
4,100 128.4 164.5
4,200 127.5 159.4
4,300 125.8 153.6
4,400 125.1 149.3
4,500 123.7 144.4
4,600 123.7 144.4

Heads up for Power

When we arrived at Jerry Choate's West Coast Classic Mustang shop in Reseda, California, for the fourth installment-Edelbrock Performer cylinder heads with 1.94/1.63-inch valves-Choate was excited by the potential of this modification. With the new heads bolted and torqued in place, Choate took the Mustang across the San Fernando Valley for another shot at Mike Morgan's dyno. The result was 176.3 hp and 230.1 lb-ft of torque. We gained a total of 47.9 hp and 36.7 lb-ft of torque with the Edelbrock head swap.

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Dyno Run No. 9
Edelbrock RPM Intake and
Carb, Hedman Headers, National
Parts Depot 21¼4-inch Exhaust
rpm power torque
2,400 95.3 208.6
2,500 101.9 214.0
2,600 106.5 215.1
2,700 110.7 215.4
2,800 114.2 214.3
2,900 117.8 213.3
3,000 121.0 211.9
3,100 124.2 211.9
3,200 126.6 207.9
3,300 129.7 206.4
3,400 132.6 204.9
3,500 135.0 202.5
3,600 137.5 200.5
3,700 140.5 199.4
3,800 142.4 196.8
3,900 144.1 194.1
4,000 145.5 191.2
4,100 147.0 188.3
4,200 149.0 186.3
4,300 149.1 182.2
4,400 150.4 179.5
4,500 150.8 176.0
4,600 149.6 170.9
4,700 149.2 166.7

Where Were We?

In the initial test we had a slow Pony and a desire to see where it could go. The base engine saw 15 dyno runs and seems to be no worse for it. Just for grins, we've included here the dyno tests from the beginning, middle, and end for your enjoyment.

It Takes a Cam...

We were feeling pretty good about our Edelbrock Performer RPM package when we received the final part of the equation, the camshaft. The Edelbrock Performer RPM flat-tappet hydraulic camshaft (PN 7122) sports an aggressive street profile. At 0.0050-inch lift, it yields 0.496-inch valve lift intake and 0.520-inch valve lift exhaust. Duration is 224 degrees intake and 234 degrees exhaust.

Choate installed the camshaft using a new dual-roller timing set and Comp Cams roller rockers. Then he ran in the camshaft at 2,500 rpm for 30 minutes and changed the oil. After a series of road tests and carb tuning, Choate was confident the recammed 289 was ready for the Morgan dyno. Keep in mind, our performance figures are at the rear wheels, not at the crankshaft.

Dyno Run No. 15
Edelbrock Performer RPM
Camshaft (PN 7122)
rpm power torque
2,400 84.5 184.8
2,500 86.8 182.3
2,600 98.8 199.5
2,700 104.9 204.1
2,800 111.3 208.7
2,900 116.7 211.3
3,000 122.8 215.1
3,100 128.0 216.9
3,200 132.9 218.1
3,300 136.6 217.4
3,400 140.7 217.3
3,500 145.4 218.1
3,600 151.1 220.5
3,700 155.5 220.7
3,800 159.3 220.2
3,900 163.5 220.2
4,000 165.5 217.3
4,100 169.0 216.5
4,200 170.8 213.6
4,300 173.4 211.8
4,400 173.4 207.0
4,500 174.7 203.9
4,600 177.0 202.1
4,700 178.6 199.6
4,800 179.5 196.6
4,900 181.5 194.5
5,000 182.4 191.6

Conclusion

So what can we conclude from this battery of swaps, tuning, and tests? That it takes a community to raise horsepower. By "community" we mean proper packaging of components and tuning to achieve the best results. We were able to boost horsepower by 54 ponies and torque by 26 pounds with the complete Edelbrock Performer RPM Power Package.

If we had our Plan for Ponies to do over, we would have opted for slightly larger exhaust pipes for improved breathing and greater torque. We also would have gone with a more aggressive roller camshaft to pump up both horsepower and torque. And this is what a plan for ponies is all about: using good street smarts to make the most of your classic Mustang power package.