|
|
|
Re: SOLID ROLLER FOR THE STREET
[Re: moparniac]
#907476
01/20/11 03:15 AM
01/20/11 03:15 AM
|
Joined: Apr 2007
Posts: 871
WA 98043
thecarfarmer
super stock
|
super stock
Joined: Apr 2007
Posts: 871
WA 98043
|
Quote:
so by these 2 which would you say is better for the street just by timing events 
bullet +++++++++++++++++++++++++++++++++++comp
Easy: the one that matches the engine better. 
Well, I can't see the seat durations; going from the .050" numbers, I'd expect the bullet with an intake closing 12.5 degrees earlier to be the better choice for low speeds. But, that's just a shot in the dark, without knowing anything about what it's going in, isn't it?
Quote:
Aggressive is the lobe profile. You can get a pretty agressive lobe with .600" valve lift and less than 250 degrees at 0.050" cam. It might be small, but does not mean it is not agressive. A profile that takes the lifter from seat to 0.050" and back in 32 degrees or less is agressive IMO. These gerenally also go from seat to 0.200" and back in less than 110 degrees. Comp, Bullet, Lunati all have several profiles that move the valve this fast but are under 250 degrees @ 0.050". Manufacturers and distributers, in my experiance, will recommend 250/600 springs for these profiles even if you're only turning it 6500 rpm. 
True that.
The grind I happen to have is pretty gentle; the 1.7:1 rockers make the lift a little high... springs would have an easier time with 1.5:1 rockers. Which is the way I'd go, except the cam isn't really optimized at all. So, if I'm going to have a cam made, might as well use a mild profile that's going to give me around .600-ish lift w/ my existing rockers.
Some cam companies have multiple series of lobes, with different characteristics and applications. Some are for limited lift app's... way nasty opening and closing; harder on valvetrain.
As far as the OP's concerns, I'd contact someone who's really, really in the know. There are some engine builders here, and on the speedtalk board who can help pick catalog lobe profiles suitable for endurance applications. Or, a person can also go to a custom cam grinder (the guys who just do 'one offs'). There's a couple of those guys on speedtalk; these are guys who actually design the lobe profiles; so that's another option.
Seduce the attractive, and charm the rest.
******
489 C.I.D., roller cam, aftermarket heads, tunnel ram, stock '54 Dodge rear axle assembly: which of these doesn't belong?
|
|
|
|
|
|
|
