Performance Q&A Tech Section

Our Resident tech guru, Big Mac, tells all.

Kevin McClelland Apr 1, 2009 0 Comment(s)

First, your transmission question hit right at home with us. Yes, you'll want to convert over to an automatic transmission for consistency and reduced maintenance. We were fighting a consistency problem with a TH350 transmission in the wagon. It would vary sometimes as much as 0.05 second between the 60- and 330-foot clocks. It would make five passes with everything repeating as expected from a mid-11-second car and then throw you a bad run. Well, it turned out that the Second gear roller clutch would skid on the gear change, and you couldn't perceive the problem in the car. It would just show up on the time slip and the win light. A 32-element sprag from ATI took care of all the inconsistency problems in this area.

Next, we changed the trans out for one of the spare B&M Powerglides for my Super Gas Roadster. We figured it was going to kill at least 0.10 second of e.t. over the TH350 because the First gear ratio went from 2.75 (Low gearset) to 1.76 stock Powerglide First gear. What this change did was give us the most consistent 60-foot times, only being off 0.004 second from our best with the TH350. With the Powerglide, our 60-foot only varies around 0.006 second for six runs in a day! The TH350 would sometimes vary 0.02 second because of the very low First gear and the way it hit the tire in the heat of the day.

We recommend going with a Powerglide transmission and a transbrake if legal in your class. Not that you're going to want to hit the tire at full throttle, but you can chip the engine power back accurately for repeatable launches. Next, you're going to need about 100 hp over your stock ZZ4 engine. This will give you enough padding to run the number when the weather turns hot and humid back in Florida. Remember, there is no replacement for displacement. This is especially true in hot, muggy conditions. It will be easier to make your 450hp goal with a 383- or 400ci small-block.

We also recommend using slicks and running a 4.56:1 rear gearset. This should put you through the lights in the 6,500-plus rpm range. Also, go with a 10-inch converter, which should stall in the 4,500 rpm range. This will put you right at torque peak of a 450hp small-block.

Finally, your engine will need a little help. You may want to pick up another engine from a local racer or buddy and sell your ZZ4 H.O. It is a perfect street engine and can be built into the engine you need. Heads, camshaft, and intake will get you there, but you will be pushing the short-block. Look around and see what deals you can come up with. Hope this gets you started. Good luck, and have fun with your new race car.

Old-School High Rise
After doing some research I found you had influence on the design of the Edelbrock Torquer II intake and the evolution of the Edelbrock single-plane intakes.

I'm in the middle of doing some upgrades to a Gen V 454 for a marine application. I recently installed a set of pocket-ported GM Vortec heads, oval-port (not peanut ports) with Ferrea Super Flow intakes and tulip-flow exhaust valves. The vane in the intake port has been blended slightly as part of the pocket-port work. The heads have a heart-shaped chamber, which should raise the CR to close to 9:1. The current intake manifold is an Edlebrock Streetmaster single-plane with a Q-jet carb and Mercruiser 496 exhaust manifolds (these have individual runners like shorty headers, which dump into a nice, gentle, sweeping exhaust elbow).

Stage II of this project is to install a Comp Cams XE262 flat-tappet cam (nitrided special grind) 218/224 duration at 0.050 inch tappet lift, 0.524/0.532 inch max lift on a 110 center and nitrided lifters. The max target for this application (marine) is 5,000 rpm. Currently I'm running the stock cam, which specs out at 213/217 duration at 0.050 inch, ground on 114 center.


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