January 2012 Chevy High Performance Q&A

Kevin McClelland Nov 23, 2011 0 Comment(s)
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Make ’Em Big, Make ‘Em Tall

Q. I’m putting together a serious 615 big-block Chevy with a Dart Big M block, a 4.625 Lunati crank, 6.7 Oliver rods, and Diamond pistons. It is going in a ’67 Camaro with a ’Glide and around a 4,000-plus stall converter. Its main duty is to run hard at the strip, and yes, it is a street-legal, full-interior, small-tire car. So, I will cruise town for fun on nice nights. My question is in regards to induction choices, by this I mean cylinder heads. The cam is a Reher Morrison 622 nitrous cam; my CR target is 14.1 and its maximum rpm is at mid 7,000. I will gear to match the engine. What would be the best head choice, and should I change my camshaft choice for this rpm range 4,500 to 7,500? With all the good spread of port heads now available, I am lost as to port size, flow numbers, and advertising hype. The engine will have a big two-stage nitrous kit for use sometimes, around 200 per kit. Any help with head choice would be greatly appreciated. Right now, I am leaning toward the Brodix PB 2005 with a minor port job. Am I way off base? Thank you for your time.

Chris Thomas
Jonesboro, AR

A. As the late Buddy Morrison used to say about cylinder head ports, “Make ’em big, make ’em tall.” The cylinder heads you have chosen would certainly fill Buddy’s requirements for power potential. The Brodix PB 2005 cylinder heads are one of the heads of choice in Top Dragster/Top Sportsman. You are building one serious street car to be going with the package you’ve outlined. These heads will only accept aftermarket components because of the relocated valve angles to 14.5- by 4-degree intake, and 6- by 4-degree exhaust valve angle. These components include pistons, valvetrain, custom-built headers, and specific intake manifold. As your letter outlines, we’re sure you’re aware of these requirements. If you’re looking to make 1,200-plus horsepower naturally aspirated, and 1,500-plus on the sauce, you’re headed in the right direction.

You can trust the numbers on the Brodix site about these cylinder heads. They will give you the level of performance and intimidation we think you’re looking for. Remember, those are little tires on your car. Keep it sunny-side up!

Source: Brodix.com

Old-School Vega

Q. I would like to duplicate Agent 87, 390 hp on a budget 355ci from your ’01 articles. In the parts list, you list 1.5 and 1.6 rocker arms. Which rocker arms did you use? Also, this engine combination will be backed by a TH350 transmission. The car is a very light ’71 Chevy Vega. I have 33-inch rear tires. Which gear ratio would work best for this engine combo? The car will be street driven only. Also, please suggest a torque converter stall size. I have these converters to choose from: 2,000-2,300, 2,300-2,700, or 2,800-3,000. Driveability is a factor, and I want to smoke the tires. Please help me with proper rearend ratio and converter choice for Agent 87 using the COMP Cams Xtreme Energy 268 cam. Also, can I swap out and use an Edelbrock Air-Gap intake instead of the Vortec Performer you used? Thank you for your time!

Jim Klug
Milwaukee, WI

A. You’ve just brought a smile to Don Hardy, the father of the V-8 Vega conversion kit. The Agent 87 engine would be a perfect choice for your lightweight Vega. But how did you get 33-inch-tall tires under the back? It must be tubbed and the tires we’re sure are wide. You said you want to “smoke the tires,” but you want to drive it on the street. For a pretty good gear compromise for street manners and to use the torque of the engine build, we recommend 4.10 gears. This will give you a 65-mph cruising around 2,700-2,800 rpm. This will work well with your 2,300- to 2,700-stall converter, and give you a top speed range of about 130 mph. Your Vega may be a little scary up at that speed flat out on city streets.

Back to your engine combination. Swapping out for the newer Vortec Air-Gap–style manifold from Edelbrock, PN 7516 would be a slight performance increase over the non-Air-Gap manifold that the Agent 87 was originally tested with. As for the rockers, we would recommend sticking with 1.5 ratio rockers with the Xtreme Energy cam profiles. Even 11 years later, good solid parts selection and testing gives you great results. Enjoy your V-8 Vega!

Source: Edelbrock.com


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