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Old 07-15-2010, 10:43 PM
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need help picking cam for sbc

Hello i'm trying to decide what cam to run in a motor i'm building for a 81 vette, hear is what i have picked so far for the motor, stock bore, flat top hyper pistons, stock crank, stock rods shot peened with arp bolts, arp main studs, Bowtie vortec small port heads, gm low rise dual plane intake (has to fit under stock hood for now) compression about 9.75-10.00 I'm trying to pick between comp 08-301-8 nx276hr cam 0.050 224 236, lsa 113 or maybe comp 08-423-8 xr276hr 224 230, lsa 110, i need to be able to run power brakes and the vacuum headlights with this motor and i don't think the xr will make sufficient vacuum at idle to run everything. I'm shooting for around 430-450hp i'm open to any input Thanks!
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Old 07-15-2010, 11:53 PM
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Quote:
Originally Posted by rx191
i'm open to any input Thanks!
Install an electric vacuum pump to operate the brakes and lights, then use whatever cam you need to in order to make the power you want. Just curious, are the heads 185's or 215's?
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Old 07-16-2010, 08:20 AM
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Do you plan on spraying? The Comp Cams # 08-301-8 is denoted as a nitrous cam.
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Old 07-16-2010, 09:11 AM
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the heads are apx 180cc on the intake side, i don't plan on spaying at all, i don't like nitrous and will never use it. i don't want to run a vacuum pump, i picked the nitrous cam because the lsa should give me a decent idle and good vacuum, also it has a longer duration on the exhaust side witch should help build good power the bowtie vortecs don't have the worlds best flow on the exhaust
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Old 07-16-2010, 03:38 PM
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alot of the time to get that kind of power (400-450) the cam that puts that out for you will hurt the power brakes, you wanting to use a roller cam? if so i think the eddy's EDL-2201 234/238 .539"/.548" would make the power you want or the compcams "Thumper" cca-12-600-8 227/241 .511"/.497" would also be a good camshaft...
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Old 07-16-2010, 04:04 PM
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I wouldn't go with that thumpr cam unless you just want a lopey idle. Check out their dyno chart on comp cams site. You'll make better power with a different cam. If you're worried about vacuum for power brakes, get something with a wider lsa, in the 112 range. The more overlap, the less vacuum is how I understand it.

http://www.popularhotrodding.com/eng...ion_angle.html


Seems a cam with an equal pattern on both sides works better on vortecs. Both of these builds use a roller cam in the 224º/224º range to achieve 440 and 447 hp.

http://www.carcraft.com/techarticles...ock/index.html

http://www.popularhotrodding.com/eng...ock/index.html
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Old 07-16-2010, 07:09 PM
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the thumper cam is way too wild for this app, they work great but have very low vacuum at idle, the edle cam is nice but has too much lift. These are not regular vortec heads, they are bow tie heads and flow quite a bit more than a standard vortec, they have a max valve lift of .545. the nx276hr has a wider lsa than any cam mentioned so far,
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Old 07-16-2010, 07:24 PM
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Have you considered going to hydroboost brakes?

Hydratech Braking

A simple vacuum reservoir would probably run the headlights.
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Old 07-16-2010, 07:29 PM
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i have debated running a hydro-boost unit, i just don't know if i want to put it on right away, i'm trying to get the car running for as little as possible (like 2000) if i have to though i will have to make the upgrade!
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Old 07-16-2010, 07:44 PM
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neither of those cams will get you 430hp. but will get you close to a real 400hp.

Neither will cause the power brakes to not function.
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Old 07-16-2010, 07:52 PM
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For sharp street performance in your vette and no fear of a PB issue call comp cams directly and get them to make you a custom hyd roller cam with 218-218@.050" 108LSA and max lift with 1.6 rockers. (.530-.540" net)
They cost the same as a catalog cam.
They have many more lobes than shown on the catalog.
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Old 07-16-2010, 10:41 PM
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thats a great idea, i will try and give them a call monday and see what they say. thanks
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Old 07-17-2010, 12:59 PM
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edelbrock bulids crate engines useing the eddy hdr roller, and puts out 420 or more hp! but seeing you want something with good vac, compcams XtreamEnergy mayb??? wanting good hp will usely end up with a cam that will hurt the vac some....but yeah give compcams a call and tell them what you have and the power you want, they can give you the cam you need!!
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