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post #1 of (permalink) Old 06-25-2001, 04:45 AM
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Need Advise on Camshaft for TBI!!!

I am putting a cam in my truck, it has the following mods thus far: Corvette aluminum heads, Doug Thorley Tri-Y headers, (Jet Hot coated) 3" exhaust all the way back, no cat, and Eaton posi with 4:10 gears. Also the little stuff, like throttle body spacer, injector spacer, high flow intake set-up with K&N. What I'm looking for is about a 5500 rpm shift point....but I understand hot cams cannot be installed in these TBI motors. I really want to lose *some* low end, due to the 4:10's, but pull harder through second, third. PLEASE HELP!!! I drive it everyday, and the heads and headers picked up driveability, and gas mileage, but EXPOSED the hideous high rpm nature of the stock cam. Thanks!!

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post #2 of (permalink) Old 06-25-2001, 02:47 PM
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Re: Need Advise on Camshaft for TBI!!!

check edelbrock or comp cams

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post #3 of (permalink) Old 06-25-2001, 03:31 PM
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Re: Need Advise on Camshaft for TBI!!!

The real key to a TBI camshaft is the manifold vacuum signal at idle. The TBI computer has several calibrations based on engine vacuum signals. A stock TBI camshaft will have about 16 - 17 Hg (inches of Mercury) of manifold vacuum at idle. If the cam you select has less the 13 Hg of manifold vacuum at idle, the TBI computer must have the PROM (Program Read Only Memory) Chip recalibrated. It's my personal experience that a cam with an intake lift of .420 and exhaust lift of .443 will usually keep manifold vacuum above 13 Hg. Besure to keep the intake lobe centerline to about 107 degrees. There are several different camshaft makers that grind such a SBC camshaft.
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