How wicked is your cam?
Thread Starter
Pro
Joined: Apr 2006
Posts: 625
Likes: 49
From: Southern California
How wicked is your cam?
In between beers at your next bench racing session, and just for fun, check your cam specs, and see how they stack-up in tech author David Vizard's "Advertised Overlap Chart" below:
10* - 40* towing
30* - 60* ordinary street
50* - 75* street performance
70* - 90* street/strip
85* - 100* race
95* - 115* Pro race
Here's how you calculate your advertised overlap:
10* - 40* towing
30* - 60* ordinary street
50* - 75* street performance
70* - 90* street/strip
85* - 100* race
95* - 115* Pro race
Here's how you calculate your advertised overlap:
- [*]
- [*]
- [*]
Burning Brakes
Joined: Feb 2006
Posts: 1,024
Likes: 1
From: AL
mine is about 60 degrees, but is a hydraulic roller which is supposed to be better in this area right?
it sounds pretty mean at idle, but smooths out quickly off idle . . . wouldn't want any wilder on the street!
it sounds pretty mean at idle, but smooths out quickly off idle . . . wouldn't want any wilder on the street!
Melting Slicks
Joined: Jun 2002
Posts: 2,844
Likes: 99
From: Orrtanna Pa.
Mine checks in where I thought (Street/strip) as it was picked from a circle track grind list.
But "wicked" it may be in a 350....same cam in a 406,...not so wicked.This tread I expect to go on for quite a while.
But "wicked" it may be in a 350....same cam in a 406,...not so wicked.This tread I expect to go on for quite a while.
Drifting
Joined: May 2005
Posts: 1,601
Likes: 0
From: BETHEL PARK PENNSYLVANIA
i ran a solid roller in my 385 cu in 61 belair
648/627 lift
270/280 dur @50
97*
sounded wicked
and yes it was streetable
5500 convertor and 4:71 gear in a 4000# car
vc
648/627 lift
270/280 dur @50
97*
sounded wicked
and yes it was streetable
5500 convertor and 4:71 gear in a 4000# car
vc
Last edited by Vette Crazzy; Oct 31, 2007 at 04:35 PM.
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Race Director
Joined: Feb 1999
Posts: 19,659
Likes: 34
From: Lenoir City Tennessee
Ci 6, 8 & 10 Veteran
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15
I have not had a chance to run the cam yet but the one in my LS conversion is a 61 by your method listed.
281+289=570
570/4=142.5
142.5-112=30.5
30.5*2=61
281+289=570
570/4=142.5
142.5-112=30.5
30.5*2=61
Last edited by Eddie 70; Oct 31, 2007 at 05:51 PM.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
That is just one of the many errors and just outright faulty thinking by author David Vizard.
Just to prove the point go to the Comp Cams list of cams PDF for small blocks. They give a bigger advertised duration number for H-flat street cams than some pure racing solid roller. The .050 number puts all cams a somewhat level playing field except for the very fast lobe lift solid roller cams
You look at it another way, compare his book with Smokey Unick's book on how to hotrod small block Chevys. You are talking 35-40 year old ideas.
Just to prove the point go to the Comp Cams list of cams PDF for small blocks. They give a bigger advertised duration number for H-flat street cams than some pure racing solid roller. The .050 number puts all cams a somewhat level playing field except for the very fast lobe lift solid roller cams
You look at it another way, compare his book with Smokey Unick's book on how to hotrod small block Chevys. You are talking 35-40 year old ideas.
Thread Starter
Pro
Joined: Apr 2006
Posts: 625
Likes: 49
From: Southern California
A buddy of mine had a 93* adv overlap cam in his big block, which had such an awesome lope, that it would turn all heads at the local cruise-in. Now he has an adv overlap of 85.5*, and it sounds positively tame, nobody looks, but it still runs 9.9's at a buck forty. I'm setting up the 540 I'm building with an adv overlap of 90*, which I'm expecting to sound pretty good.
It appears that a really awesome chop starts at right around 90* adv overlap, so hopefully I'll have enough to turn heads too.
GKull, I guess the laws of Phyics don't care if the idea is decades old or not. Lots of overlap gives a good chop, always has, always will
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
They are both 110 So they score within a one point or so. That is just wrong. H flat of 230/230 @ .050 does not run like 242/248 @ .050 solid roller
Race Director
Joined: Apr 2000
Posts: 17,676
Likes: 201
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
I would agree with the chart for fat tappet cams, roller cams are a whole new ballgame, much higher lifts at lower durations are the main reason for putting one in
Le Mans Master
Joined: Oct 2000
Posts: 7,831
Likes: 5
From: Austin TX
