Posted By: Cudajon
Gotta CAM question thats been bugging me... - 08/23/11 03:25 AM
In all the cam catalogs they will show a cams operating range like 2500 - 7000 rpm. But those are always for stock or nearly stock displacement engines. So with my 494 what would be a good rule of thumb for adjusting the operating range of the CAM or is there one?
Posted By: Crizila
Re: Gotta CAM question thats been bugging me... - 08/23/11 03:42 PM
"GENERAL" rule of thumb: For every 50 cubes more over stock, the power range drops 100-150 rpm - from advertised.
Posted By: RobX4406
Re: Gotta CAM question thats been bugging me... - 08/23/11 05:58 PM
Take those operating ranges with a grain of salt.
As an example. A recent 408 was done with a 60403 Lunati, Lunati says the operating range is 1800-6200. The 408 was done at 5300-5400. That cam may have made it to 6200 if it was a 340. How would the same cam run in a 273?
I usually assume the RPM range they state is the middle of the ovarall engine family size range.
With a 494 and a cam that has a catalog 7000 top range, I'd bet it's all done producing incremental HP by 6200 or so.
Talk with an engine builder and see what they say. Most of the time, custom cams can be cut and priced real close to the shelf stuff, if not better.
Posted By: bumps440
Re: Gotta CAM question thats been bugging me... - 08/23/11 09:18 PM
most important factor in rpm range is cylinder head flow. good flowing heads will require less duration to make the same power and rpms as a bad flowing head and more duration. actuall will make more HP. study things like CSA and choke of the port.
This is a very general statement so keep that in mind, your always better off in dealing with a competent source(cam grinder, engine builder of motors like yours) of informamtion when picking cam grinds :scopeout
