Chevy Drag Racing - Watch The Details

Performance Q&A

Kevin McClelland Jul 1, 2006 0 Comment(s)

A Your Chevelle should have some snap in the throttle response, and your package should give you good performance. We need to start talking total timing, not initial. But first I would like to talk about cam timing. Did you degree the camshaft when you installed it? With 18 degrees of initial, the engine should have good performance and throttle response. The XE268 Comp Cams is a good size camshaft for your 327, and the 462 cylinder heads were the mainstay of performance through the '60s and '70s. If the camshaft was installed a tooth retarded, or the cam or crank gear was machined incorrectly, this would really hurt the performance of your engine. Check on Comp's Web site for instructions to degree the cam. The XE line of camshafts are ground with 110 separation angle, and the intake centerline was ground with 4 degrees advance. This puts the intake lobe in at 106 degrees ATDC. I would recommend checking this out first before spending any money on new components. As for spark advance, your 327 engine buildup will want between 34 to 36 degrees total timing that is all in by around 3,200 rpm. From there you can see where your initial timing falls. You may need to limit the amount of mechanical advance to get the initial timing in a range you like. An initial timing of 18 degrees will give you great throttle response and slow-speed performance. If you run your Chevelle on super unleaded (91 here in California!), you should have no problem with these timing specs.

You said that you have a very unpleasant (glasspack) exhaust note. This leads me to believe that the camshaft may be retarded. No, I don't think an X-pipe will give you better sound. Also, you said you have stock exhaust manifolds. If you went to four-tube headers, you would gain around 20 to 30 lb-ft of torque, below torque peak. It's just a thought. Good luck.

C-Clip SafetyQ I have a '72 Chevy Nova with a 468ci big-block and a TH350 trans. The rearend is the factory 8.5-inch 10-bolt with Richmond gears and an Auburn posi. I also have Slide-A-Link traction bars, monoleaf springs, and factory C-clip axles. The car runs consistent 7.40s in the eighth-mile and I have been able to run a best of 7.06-only I have never been able to do that since!

While I'm pleased with the way the car runs, I want to go quicker. My concern is the stock C-clip axles being the weak link. When I originally started the project, the idea was for a street/strip machine. After burning up multiple transmissions driving the car around town, and getting tickets for the loud exhaust, I have decided that driving it on the street is not an option. Needless to say, the car and I are much happier now.

If I change to hardened axles, will the rest of the rearend take the abuse of drag racing? And how hard would it be to change it over to a 9-inch Ford? I read somewhere that a 9-inch out of a '69 Cougar is almost a direct bolt-in. Is this true? I happen to have one and the dimensions look like it will fit, but the spring perch is a little different. Another concern is the emergency brake cable. Will the Nova cable work or is there another aftermarket setup out there? Are there any other issues that I need to be aware of to do this swap?Clifford ArnettBlooming Grove, TX

A That is one running Nova. If you convert the eighth-mile time into quarter-mile, you're running in the 11.40s, and your quick run puts you at a 10.88! That's hauling the mail for your little street Nova. We would be much happier, as would the NHRA tech department, if you would get those stock axles out of your car.


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