September 2011 Chevy High Performance Q & A

Knowing When To Say When

Kevin McClelland Jul 28, 2011 0 Comment(s)
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For Pro Touring and spirited road driving and track days, check out the component Hotchkis Suspension offers for the rear of your Camaro, complete rear suspension packages that give you multileaf rear springs, rear sway bar, and hardware. The rear springs are 3-inch lowering springs featuring a multileaf design with a 3/4-length overload spring to reduce axlewrap. The front mount is a high-durometer rubber and the rear mounting is a polyurethane bushing. This kit (PN 2413C) comes with the springs, bushings, and new shackles. Next, you need to tie all that torque your ZZ502 is kicking out with the rear unibody frame. Hotchkis offers beautiful weld-in subframe connectors (PN 4007) that feature 1.5x2.5-inch rectangle, 0.120-inch-wall tubing. They require no cutting to install, and give you the most ground clearance possible. They are powdercoated black and are supplied with a polyurethane subframe mount to attach the front mounting point.

Now, if you’re more of a “straight line” guy, check out what Calvert Racing has to offer for the rear of your Camaro. The Cal-Tracks traction enhancing devices for leaf-spring rear suspension have won more NHRA Stock eliminator titles than any other leaf-spring traction device on the market. Calvert also has two-piece monoleaf rear springs for Camaros to work in conjunction with their specific traction device.


Plenty of Fuel

Q: My ’70 Chevelle SS has a ZZ502, an 850-cfm Demon carb, Hookers, a Hughes Turbo 400 with a GM25 converter, and a stock 3.31 posi. I spoke to Demon because I have installed bigger jets several times, currently 88 primaries and 93 secondaries, and the plugs are just barely starting to show a bit of tan color. The guy at Demon said if I have to put jets that big into that carb then it is starving for fuel. The fuel system is a stock tank pick-up and 18 inches of 1/2-inch rubber hose, a Holley HP125 pump, 24 inches of 1/2-inch hose with a Jeg’s screen filter in the middle. Then I go back to stock steel 3/8-inch line up the frame to engine compartment then 1/2-inch rubber hose to both inlets on carb. The Demon tech said I need a bigger pick-up tube in the tank and also change the stock steel 3/8-inch line on the frame to 1/2 inch. I can’t find anyone who makes a tank unit with a bigger pickup tube. Help!

Tim Raubinger
Wasilla, AK

A: Hey, Tim, you and George hang out at the same dragstrip in Alaska? What a coincidence. We rarely hear from you guys from up north! Your 502 will live just fine with the 3/8-inch pickup and fuel line. Let’s talk.

We’ve run a 502/502 in a ’72 Chevelle with a Carter electric pump at the tank and full 3/8-inch line and factory Holley-type fuel distribution lines at the carburetor. This Chevelle ran great on the dragstrip, handling challenges, and braking. We built this Chevelle for Flowmaster for the Hot Rod Power Tour. It was Richard Small’s and it was used by several magazines for many performance challenges.

Back to reading your spark plugs. With unleaded fuel, the center electrodes will be perfectly white when the engine is fueled correctly. We run our 524 in our roadster on the rich side. With our Racepak data logger recording the wideband O2 sensor, the air/fuel ranges between 11.9 and 12.2 from the starting line to the finish. We keep it on the rich side to make it less sensitive to atmospheric changes and to help prevent detonation. When we check out the plugs in this engine after 50 dragstrip passes they are still perfectly white! You will never see color on the center electrode that you would with leaded-type fuels. The only true way to set the jetting on your Chevelle is either through performance testing to the highest mph on the dragstrip, or with a wideband O2—the O2 is the easy way to go.


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