Bolt and Go, Part III

Testing Holley’s Street Avenger Aluminum Heads

Bob Mehlhoff Jun 1, 2002 0 Comment(s)

Step By Step

The Holley SysteMAX aluminum cylinder heads weigh 30 pounds assembled and feature screw-in studs, guide plates, heavy-duty springs, and a 20-degree valve angle, which allows improved valve positioning in the cylinder bore. The 2.02-/1.60-inch valves with a three-angle cut provide excellent intake and exhaust flow and have runners designed to optimize breathing.

Before installing new heads, it’s key to clean the thread holes with a thread restorer to allow accurate torque readings.

For proper cylinder head sealing we chose a set of Fel-Pro head gaskets. Prior to installing any new gasket, remember to thoroughly clean the block’s deck from all gasket material and residue.

We added ARP’s thread sealer to each head bolt to achieve the correct torque specifications. Dry, uncoated head bolts produce lower clamp loads due to greater friction between the threads. With aluminum heads, always remember to use hardened washers to avoid galling the soft metal casting.

Our ARP head bolts required a torque setting of 65 ft-lb. To achieve this specification, we followed the correct torque sequence and began tightening from 45 ft-lb measurements and added 5 ft-lb increments until 65 ft-lb. After the final tightening, we checked all head bolts again.

The Weiand Action-Plus aluminum intake manifold is designed to provide good performance from idle to 6,000 rpm. The SysteMAX cylinder head requires Lunati’s 8.040-inch hardened pushrods that replace stock 7.80-inch pieces. We installed a set of Lunati’s aluminum roller rockers with locking nuts for improved valvetrain control.

Reider Racing supplied an installation kit...

...an Eaton Posi unit...

...and a set of Precision 3.73 gears for our Nova’s corporate 8.50-inch 10-bolt rearend.

To make use of this extra power, we replaced the open 3.08 cog with lower gears and a posi unit. To do that we contacted Reider Racing.

Proper gear installation is essential to quiet and extended gear life and requires the right tools and experience. Moore set the Nova’s ring-and-pinion to 0.008-inch backlash and the correct tooth pattern. Reider Racing/Precision Gear recommends 0.008- to 0.010-inch backlash measurement.

Next we installed the 10-bolt housing back into the Nova and topped the rearend off with new GL-5 lubricant and a posi additive. To break in the gears properly, we put 200-300 miles on the Nova at part-throttle without any hard acceleration. Finally, we drained and replaced the rearend lube and looked forward to lower e.t. slips.

For our final testing, we disconnected the front sway bar for better weight transfer and adjusted the rear tire pressure to 13 psi to improve traction. On our final pass our 350 Nova stopped the clocks at a corrected 13.37 e.t. at 102.18 mph. Holley’s Pure Street System transformed our Nova from stone stock to a pure blast.

Build it faster, quicker, and keep it streetable. That’s what Chevy gearheads wake up for each morning. If you’ve been following CHP’s Bolt and Go series, you’ve watched us add the first two stages of Holley’s new Street Avenger System’s Pure Street package to our test Nova. The first two stages of the Pure Street package focused on improving engine power by adding a 670-cfm Holley Street Avenger carburetor, Weiand Action-Plus intake, a Lunati camshaft, an Annihilator ignition, and a Hooker exhaust system. To enhance those performance bolt-ons, we gave the Nova more stall speed by adding an Art Carr 10-inch converter. With those changes we transformed our stock 350 Goodwrench Nova from a bland 17.27 at 79.16 mph cruiser to a spicy 14.81 at 93.89 mph performer.

This time we pushed the performance envelope further when we pulled the iron Goodwrench heads and added the Pure Street Stage 3 Holley SysteMAX aluminum cylinder heads. To complement our newfound power, we also canned the Nova’s lackluster 3.08 open rearend and installed a set of Reider Racing 3.73 gears and an Eaton posi unit. So hang on as we wring more e.t. out of our Nova and land deeply into the 13s.

Head for the Street

To add even more performance synergy to the Pure Street System, the Stage 3 package offers a set of good-flowing Holley SysteMAX aluminum cylinder heads that provide 185cc intake ports with 2.02-/1.60-inch valves. After seeing those kinds of stats we could hardly wait to start unscrewing the stock 1.94-/1.50-valve iron castings from our 350 and bolt on the new aluminum heads.

With the heads off, we removed all the old gasket material from the block’s deck and cleaned all the head bolt holes. Then we picked up a set of ARP head bolts with washers to eliminate the chance of galling the aluminum castings. After torquing >> the heads into place, we installed a set of Lunati’s hardened 8.040-inch pushrods to match the SysteMAX’s valvetrain geometry.

Although our Goodwrench 350’s stock rocker arms could probably have survived the Nova’s dragstrip duty, we opted for a set of Lunati 1.6 aluminum roller-rocker arms.

With coolant back in the motor and everything set, we noticed that the better breathing heads demonstrated improved performance, especially in the mid to upper rpm ranges. The following Friday night we drove the Nova through L.A. traffic for two hours to Los Angeles County Raceway (LACR) in Palmdale. With our late arrival and the crowded staging lanes, we could only make one run and stopped the clocks with a corrected 14.43 at 95.86 mph, which netted almost a 0.40-second and 2-mph improvement from our last track outing running the stock iron heads.

This demonstrated that with our increasing midrange power gains, we really needed a set of gears. So we contacted the folks at Reider Racing to help out. Reider Racing suggested a set of 3.73 Precision Gears, an installation kit, and an Eaton posi unit to allow the Nova to leave the starting line hard and continue crisp acceleration down the track. Plus the 3.73s are not too deep for our freeway commutes.

Because proper gear installation is critical, we contacted our good friend Tim Moore to help out. With Moore’s experience and tools, the installation took just a few hours of bench time. After we allowed the gears to break in we found the Nova’s off-the-line performance had improved tremendously. Keeping the tires from breaking loose would be a challenge, though, so we borrowed a pair of Mickey Thompson E.T. Street tires and stuffed them in the trunk. At freeway speeds, the engine ran at around 3,500 rpm throughout our 90-mile trip to the LACR. We installed the E.T. Streets at the track and adjusted the tire pressure to about 15 psi. After a few passes, we had the Nova stopping the clocks at a very respectable 13.58 at 100.07 mph, but we still felt we could drop more time. Although the Nova was hooking reasonably well on the starting line, we still couldn’t give the engine full-throttle or else the tires would break loose. Back in the pits we disconnected the front sway bar for improved weight transfer and adjusted the rear tire pressure to 13 psi.

Our efforts paid off on our next pass when the Nova ran a corrected 13.37 at 102.18 mph. Since we began installing the Holley Street Avenger Pure Street System our quarter-mile e.t. has improved by almost 4 seconds and the mph has increased an astounding 23 mph. Each stage of the Holley Pure Street System also increased the Nova’s fun-factor. Best of all, the Nova is still very streetable. The trip to and from LACR is about 180 miles, and the Nova has always made each trek flawlessly in freeway traffic. That’s what the whole dyno-matched Holley Street Avenger System is all about—pure performance in a very streetable package.

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