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Custom grind cam card specs - Note equal lift/duration and higher lobe separation
(click image to enlarge) |
No engine rebuild, stock or performance, would be complete without a new camshaft and lifters (and possibly valve springs). The camshaft sets the mood for your engine build. Once you pick your camshaft, you have to make sure the rest of your build is designed to support it's properties. The camshaft controls valve timing and in turn, fuel economy, performance and idle quality. In order to choose the correct camshaft you have to consider the parts you have, and are planning to use. This article is not intended to help you pick a camshaft for your build. Consider researching this topic extensively before committing to a camshaft. A lot of the manufacturers have tools to help you pick one out or sales reps with cam calculators to pick the best cam specs for you. For more information on cam specs and selection, check out
this unaffiliated page.
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| New cam needs new lifters - Model #812-12 |
Turbo Camaro runs a Chevy 250 inline 6 and the rebuild intends to add a large turbo and alcohol injection. The goal is to get between double and triple the stock horsepower. This goal is by no means out of the question but when picking a cam the addition of a turbocharger changes the selection drastically. A turbocharger allows the engine to run "normally" when not in boost, but have significant power and RPM bursts when in boost. Based on the build plan, all the internet forums and CompCams agreed, the custom C61 5232 grind was ideal. A picture of the cam card can be seen on this page. The important guidelines were to keep the intake and exhaust valve duration/lift the same, or almost the same. The lobe separation needed to be fairly high to maintain a smooth idle and allow the turbo to build power at higher speed/RPM. Overall, it's a mild cam that should allow solid daily driver performance and effective use of the turbocharger when desired.
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| Cam inspected through the bag but not pulled until install. |
Due to the increase in lift, the stock valve springs won't last. A new performance valve spring and retainer kit was ordered from Tom Lowe at
www.12bolt.com. The springs are a direct replacement for the stock springs, but have the appropriate tension for the increased lift (up to .530).
The stock camshaft timing gear is made of a fibrous material, that was designed to be light and quiet. The fiber gear is a weak link in a performance setup and should be replaced with a metal gear. The CompCams steel timing gear set was purchased for this reason. The
machine shop service list includes heat-pressing the steel gear on the new camshaft. Keep in mind, you can purchase different timing gear sets, some with steel and/or aluminum gears and different keyways allowing you to advance or retard cam timing easily.
Once the above components are installed, further images and information will be added here.
Turbo | Camaro
