Yo people, i want to do a cam/lifter preformance swap on my 2.9L, but i dont understand how to read what the heck all the jargan is, all i want is a low rpm increased torque cam aka: RV cam.

This is the info I got from Cam Craft Cams
2.9L V6 1.47 Rocker Ratio

Cam and lifter kit $225.00 + shipping
All new designs for 2001 (advertised duration is checked @ .004!!)

Part# / adv. Dur .050 dur. Valve lift lobe sep.

H39-9898 248/248 198/198 .405/.405 109

H39-9802 248/252 198/202 .405/.412 109

H39-0202 252/252 202/202 .412/.412 109

H39-0206 252/256 202/206 .412/.412 110

H39-0606 256/256 206/206 .412/.412 110

What the heck does all this above mean in english!

Here are a few simple explanations

Advertised duration: the number of degrees from when the valve starts opening until it closes. intake/exhaust

Duration @.050: number of degrees of valve opening starting measuring when the valve is open 50/1000" intake/exhaust

Lift: Gross valve lift in thousandths of an inch, gross valve lift is lobe lift multiplied by the ratio of the rocker arm.

Lobe lift: Amount of lift of the lobe of the camshaft without factoring in the rocker arm ratio.

Lobe separation: Number of degrees between the opening of the intake valve and the opening of the exhaust valve.

Overlap: Number of degrees where both intake and exhaust valve are open.

Single pattern: Both intake and exhaust have the same number of degrees of opening and the same amount of lift.

Dual pattern: Intake and exhaust have different number of degrees of opening and/or amount of lift.

Grind: Camshafts are ground to give a specific profile. Camshaft part numbers are also refered to as grind numbers.

Also note that the profile of the lobe has an effect on the way a particular grind will work. Flat tappet camshafts have a less agressive profile than roller tappet camshafts because a flat tappet cannot follow as steep a ramp as a roller tappet.


Long duration camshafts affect the idle quality and the amount of vacuum that an engine produces. Higher lift means that the valve opens more resulting in more airflow. Lobe separation affects overlap. The smaller the displacement of the engine the more effect the changes have.


What's the difference between advertised and @.050?

Advertised duraton is a relative term. Relative to where the manufacturer starts measuring. In the case of the list you show, they start measuring advertised at .004" of tappet lift. Some manufacturers use more conservative advertised durations (ie: Comp Cams) and some use more optimistic advertised durations (ie: Crane Cams) either way you can't really go by advertised alone. That's why they give you the other specs.

An example is the cam that I have in my 302. It is a Comp Cams 270H Magnum, advertised is 270 degrees , @.050 is 224 degrees, .500 lift with 110 degree lobe separation has an equivalent in the Crane catalog that has a 286 degree advertised duration.

Read this for more details and if I made any mistakes hopefully they weren't big ones. http://www.compcams.com/information/tutorials/

wow thanx dude! apreciate the detailed explanation :beer: :smokin: