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Old 09-18-2008, 10:01 PM
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Help with cam choice

I've been trying to finish my 496 that I am building and I came across the edelbrock rollin' thunder cam and decided to see what it would do in my desktop dyno. It made more horsepower and torque at a lower rpm and it has less overlap. The weird thing is it has more duration then the cam I was going to use. I would like to get your opinions on these cams.
Comp xr288hr:
Dur.288/294 @.050-236/242 .521/.540 110 lobe sep. and 71 deg of overlap

edlebrock 2263
dur. 308/315 @.050-248/256 .629/643 112 lobe sep. and 28 deg of overlap

The engine has 9.5cr with afr 305 heads and I havent decided on an intake yet but am leaning towards a rpm airgap over a vic jr.
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Old 09-19-2008, 01:39 AM
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You will definitely want to go the dual plane route, instead of the Victor Jr., but might want to take a look at the Weiand Stealth. It has larger runners to breathe better upstairs. I just swapped from a Weiand 7622 to a Stealth, and it is night and day difference.

On your cam choice, you compression is your limiting factor. If you had a point more, you would be able to use more cam, and take full advantage of those heads. I have the same set, 114cc CNC chambers in my 10.5-1 496 with a Voodoo Solid Roller 60234.

Why Hydraulic roller? Ever think about a solid ft? You can get the same performance as a Hydraulic roller, without the heavy rollers, cost, and rpm limitations. Good polylocks and adjust once a year.

Lunati 402A5:
Advertised Duration (Int/Exh): 285/295
Duration @ .050 (Int/Exh): 252/261
Gross Valve Lift (Int/Exh): .595/.595
LSA/ICL: 110/104
Valve Lash (Int/Exh): .025/.025
Solid, rough idle. Excellent street/bracket racing cam with very strong mid-range and top end torque and horsepower. Needs 3000-3500 RPM stall converter, headers, 10:1 compression ratio or better and 4.10 gearing.
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Old 09-19-2008, 03:19 PM
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you are comparing overlap at advertised duration with overlap at 0.050" duration. (not a good comparison)

The compcam has 71 degrees overlap at advertised duration and 19 degrees at 0.050"

The edelbrock cam has 87 degrees overlap at advertised and 28 at 0.050".

what gears and stall are you running?
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Old 09-19-2008, 07:45 PM
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I didnt even notice that 454c10. Now it makes sense . Its getting a tko 950 and 4.10 gears. I havent fully decided on a hyd roller just yet and am still weighing my options. I only want 9.5 compression because it has to run on 91 and don't want to be on the verge of detonation. They reason I was thinking a vic jr because I haven't decided if i want to run an EFI setup yet.
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Old 09-19-2008, 08:35 PM
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You can easily get by with a dcr (dynamic compression ratio) of 7.25:1 with a 496 and afr heads and 91 octane.

check out this site. easy to calculate drc.

http://www.projectpontiac.com/ppsite...nt/view/16/30/

As for the cam, the intake closing point is what effects the dcr

I'm think you could run 10:1 cr with those heads and a cam in the 290-300 degree range (advertised) with 110 LSA and 91 octane. No need to run more exhaust than intake duration due to the good flowing exhaust ports on those heads.
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Old 09-19-2008, 09:44 PM
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I went through every solid roller cam I could find on summit and only one came close to how much the edelbrock cam did without losing a lot of low end. I put my specs in that calculator and got 7.44 dcr. That seems pretty good if you say I can get away with a 7.25. Is looking at different cams side by side on desktop dyno a fair comparison or are there other important parts missing?
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Old 09-20-2008, 06:54 AM
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that edelbrock cam has a lot of lift. That will be hard on the lift train.

what static compression does you engine have?

7.4 dcr should be ok with aluminum heads and a 496. That 4.11 gear will also help reduce ping.
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Old 09-20-2008, 09:31 AM
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It has roughly 9.52. I thought lift in .600 range was normal? Almost every cam I look at has more than .600 lift.
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