Welcome to Just Commodores, a site specifically designed for all people who share the same passion as yourself.

New Posts Contact us

Just Commodores Forum Community

It takes just a moment to join our fantastic community

Register

How do you read cam specs? What do the numbers mean?

crazybiker

Member
Joined
Sep 9, 2008
Messages
703
Reaction score
3
Points
18
Location
Sydney NSW
Members Ride
VR Commodore V6
I've been reading a few threads lately, and a few people have posted some cam specs, and I've been urging to know what they mean exactly.

For eg: "280/286 .612 .615"

I got that out of 'DARTVXCLUBBY's' thread about his new LS1.

What do those numbers mean?

...and if possible could I get a medium description to, rather than First number means this...only if possible though.

Thanks
 

delcowizzid

on holiday
Joined
Jul 8, 2008
Messages
6,988
Reaction score
445
Points
83
Location
NZ
Members Ride
в∞ѕтεכ √&
intake valve open duration/exhaust valve open duration . intake valve lift/exhaust valve lift
 

delcowizzid

on holiday
Joined
Jul 8, 2008
Messages
6,988
Reaction score
445
Points
83
Location
NZ
Members Ride
в∞ѕтεכ √&
and the duration is degrees of rotation in crank degrees not cam
 

VT-565

New Member
Joined
Apr 4, 2005
Messages
2,773
Reaction score
56
Points
0
Location
QLD
Members Ride
VT
I wonder if that lift is at the lobe or at the valve? surely has to be at the valve.
 

delcowizzid

on holiday
Joined
Jul 8, 2008
Messages
6,988
Reaction score
445
Points
83
Location
NZ
Members Ride
в∞ѕтεכ √&
it will be valve lift
 

VT-565

New Member
Joined
Apr 4, 2005
Messages
2,773
Reaction score
56
Points
0
Location
QLD
Members Ride
VT
Ok, just to further answer crazybiker, on most cam cards, they will specify lift at the lobe then lift at the valve, obviously lift at the valve will be determined by what ratio rockers you have, they will specify what ratio they used to arrive at valve lift figure too.

I'll post mine up later, my cards at home, It's a monster :)
I might even try scan it to give you an idea what they are on about, mate.
 

greenfoam

New Member
Joined
Jan 13, 2005
Messages
7,902
Reaction score
128
Points
0
Age
102
Members Ride
VP Executive R-spec
I'm going to have to write up that cam spec how to I was supposed to write over Easter, it's pretty complex but I'll try my best to explain everything so you can keep comming back to it as you figure out more and more, the most important figures are the intake and exhaust timings at .050 inches, advertised duration doesn't mean alot
 

delcowizzid

on holiday
Joined
Jul 8, 2008
Messages
6,988
Reaction score
445
Points
83
Location
NZ
Members Ride
в∞ѕтεכ √&
yeah you mean that cam thread you started ages ago and never got back too LOL:yeah: . the .050 figure allows for the ramp rate of the lobes .with all the figures you can work out anything you want
 

VT-565

New Member
Joined
Apr 4, 2005
Messages
2,773
Reaction score
56
Points
0
Location
QLD
Members Ride
VT
cam is the brain of the engine. very important to get it right or close to it.
 
Last edited:
Top