Cam lession #101
Thread Starter
Melting Slicks
Joined: Aug 2005
Posts: 2,683
Likes: 34
From: Working on the car NY
Cam lession #101
Why are some cams "the same" or close on intake and exhaust (.472"/.480") while other have a much bigger spread (.474".510'). What's the upside/downside of going with one vs. the other? Also, how does "lobe seperation" figure in on all of this
. Thanks,
. Thanks,
Melting Slicks
Joined: Oct 2002
Posts: 2,317
Likes: 111
From: St Louis MO
There's lots to read that's already been written. A good source is on Isky cams website:
http://www.iskycams.com/techtips.php
http://www.iskycams.com/techtips.php
Burning Brakes
Joined: May 2008
Posts: 860
Likes: 0
From: Stratford Ontario
To make it easy to understand without getting to technical. The cams with more lift on the exhaust side is to try to help poor flowing exhaust in the cylinder head. Heads that flow 75% or better on the exhaust side compared to intake don't need the extra exhaust. Your lobe separation is where You will either get more or less lump or hack at idle, although its meant to increase power at higher RPM,s. Hope this helps.
. I also read that Isky stuff 
.
Race Director
Joined: Sep 1999
Posts: 11,361
Likes: 383
From: Plano TX
Not just the exhaust port in the head: If you have stock iron manifolds and restrictive stock mufflers you'd want a "bigger" exhaust lobe (longer duration, more lift). With headers and good exhaust + good heads you may find the most power with the same lift/duration on intake and exhaust.
Melting Slicks
Joined: Mar 2005
Posts: 2,838
Likes: 10
From: Austin TX
Agree with the above. These days, dual pattern cams are seemingly recommended for every engine build. But I've proven (at least to myself) at the dyno time and time again, that with good flowing heads (especially on the exhaust side) and a good flowing exhaust system, a single pattern cam will flat out-perform a dual pattern cam.
More info here:
http://www.camaros.net/forums/showth...e+dual+pattern
More info here:
http://www.camaros.net/forums/showth...e+dual+pattern
