Re: Cam selection 520ci
[Re: RRandP92]
#2486920
04/23/18 06:14 PM
04/23/18 06:14 PM
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Joined: Jan 2003
Posts: 13,382 Marion, South Carolina [><]
an8sec70cuda
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 13,382
Marion, South Carolina [><]
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You said you're happy w/ a cam you got from Porter Racing in another motor...talk it over w/ Dwayne. He won't sell you something you don't need and is a wealth of knowledge w/ these types of combos.
CHIP '70 hemicuda, 575" Hemi, 727, Dana 60 '69 road runner, 440-6, 18 spline 4 speed, Dana 60 '71 Demon, 340, low gear 904, 8.75 '73 Chrysler New Yorker, 440, 727, 8.75 '90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt '06 GMC 2500HD LBZ Duramax
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Re: Cam selection 520ci
[Re: RRandP92]
#2486921
04/23/18 06:16 PM
04/23/18 06:16 PM
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crabman173
Unregistered
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crabman173
Unregistered
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Conventional wisdom is wider LSA with more cubes--OK but I have had better luck in general not going that route and staying in the 110 max range and as for Crane--the one custom I had done by them for a six pack 511 CI was a dud--way too wide LSA just no balls made 40 HP less than it should with our regular stuff with no other advantages Porter made you happy trust HIM again--right?
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Re: Cam selection 520ci
[Re: RRandP92]
#2487107
04/24/18 02:58 AM
04/24/18 02:58 AM
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Joined: Aug 2003
Posts: 43,274 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,274
Bend,OR USA
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My first pump gas 511 C.I. 400 stoker motor ended up with a set of Indy M.W. SR non ported heads on it with a 400-3 intake and a old Holley 9375 non HP 1050 CFM carb on it, I bought a Comp Cams new custom ground solid roller cam from a member on here that worked excellent, it was 260 @.050 on the intakes with .420 lobe lift, 266 @.050 on the exhaust lobes with .409 lobe lift ground on a 108 LSA installed at 106 to 107 ILC. I switch to a set of Harland Sharp 1.65 ratio rockers after doing the first head swap from the original ported big valve 906 iron heads to a set of CNC ported Eddy RPM heads before switching the heads later to a set of Indy SR M.W port size heads(which increased the compression ratio from 10.29 to 1 to 10.78 to 1) several years later, same cam and lifters. That combination loved being shifted at or above 7000 RPM to get the best times the track no matter which heads, intake or carb sizes I ran on it I have never used NOS so keep that in mind also I wouldn't be afraid to run that same combination with NOS though after discussing it with a friend who has raced a bunch of different motors and cars with NOS on them, he like tighter LSA cams than wider ones also for NOS
Last edited by Cab_Burge; 04/24/18 03:01 AM.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Cam selection 520ci
[Re: AndyF]
#2487429
04/24/18 07:10 PM
04/24/18 07:10 PM
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crabman173
Unregistered
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crabman173
Unregistered
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One thing I learned the hard way is that the TF heads are easy to over cam since they have really good flow at low lift. If the lobe is too fast you'll end up with reversion and the engine will not make the power you were expecting.
Dwayne has a good handle on this since he has watched my test results. Give him a call and ask about the Comp cam that you already have. It might be fine for what you're doing. Interesting there Andy Most cam folks see that big CI and just lay the lobe to it We have had some great running big CI units with smaller than you would expect on the cam---well...I really can say that about most every engine for street Over the decades we have about decided that no cam is too big on a REAL race engine and smaller almost always seems to make a better street engine overall I have always been against the" use every MM of the lifter diameter" for most guys as it gives away that safety margin Mopars enjoy and for what? a few extra HP on a unit that will have plenty? Just never made sense to me With all the stroker stuff these days most street guys can't stick it to the road anyway and that 340 4 speed with a 410 gear walks off from them better than they thought
Last edited by crabman173; 04/24/18 07:10 PM.
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Re: Cam selection 520ci
[Re: RRandP92]
#2487463
04/24/18 08:35 PM
04/24/18 08:35 PM
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Joined: Oct 2007
Posts: 4,210 New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,210
New York
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More displacement means less valve area per cubic inch = more overlap, and smaller LSA. Those high LSA numbers are how you hide the displacement when the duration is huge.
Boffin Emeritus
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