I will paste my cam card. This is an older Crane cam given to me by my buddy Len Bently (crazy old beer drinking guy-an indicator of a rich character, of course). Is this a "fast ramp" cam? I have been searching around, there is lots of different info (and some disagreements). A couple guys mentioned increased valvetrain noise, I don't know. How does this baby look for a 9.something:1 455 w/Al heads? Car has headers, lower gears, TCI breakaway w/TH200-4R, Al Stg 1 heads w/matched performer. Thanx for sharing some insight. Part Number: 85H000006 Grind Number: H-234/325-2-12 Engine Ident: 1967-1976 BUICK V-8 400-430-455 CU.IN. VALVE SETTING: INTAKE .000 EXHAUST .000 ----> HOT LIFT: INTAKE @CAM 325 @VALVE 520 ROCKER ARM RATIO EXHAUST @CAM 3387 @VALVE 542 1.60 ALL LIFTS ARE BASED ON ZERO LASH AND THEORETICAL ROCKER ARM RATIOS CAM TIMING OPENS CLOSES ADV DURATION @ .004 INTAKE 41.0 BTDC 83.0 ABDC 304.0 TAPPET LIFT EXHAUST 90.0 BBDC 44.0 ATDC 314.0 SPRING REQUIREMENTS TRIPLE DUAL OUTER INNER PART NUMBER 99838 LOADS: CLOSED 110 LBS @ 1.688 OR 1 11/16 OPEN 338 LBS @ 1.168 RECOMMENDED RPM RANGE WITH MATCHING COMPONENTS MINIMUM RPM 3000 MAXIMUM RPM 6500 VALVE FLOAT 7000 CAM TIMING OPENS CLOSES MAX LIFT DURATION @ .050 INTAKE 10.0 BTDC 44.0 ABDC 107 ATDC 234.0 TAPPET LIFT EXHAUST 59.0 BBDC 5.0 ATDC 117 BTDC 244.0
That looks like an excellent cam! It's not a fast ramper, you can tell by subtracting .050 duration(234/244) from .004 duration(304/314). It's more like a slow ramper, should be easy on the valvetrain. AND it has good lift for its size. Steve Walsh
Yea, I just read a big article on cams. It said that the lower the number between the two, the faster ramp the cam is. I think they said that cams that have a difference below 50 are "fast ramp" cams. This cam's difference is 60. It seems that a lot of performance cams are in the 54-60 range.
Apples and oranges here. Crane rates their advertised duration at 0.004" TL while most others in the industry rate theirs at 0.006". So the 0.050" to adv points can't be directly compared.
You really can't tell if it is a fast ramp cam by comparing the .050" figure with the advertised... the only thing that will tell you is what the low lift rate is like. Think of it this way- the difference between the .006" and .050" lift rate is very little lift change. But, from .050" to full lift there is a major change in lift. What it comes down to is that only the manufacturer knows the ramp profile. For example- Poston's version of the Kenne Bell 107 "window rattler" is a fast ramp cam, but the difference in duration between the advertised and the .050" lift figures is 60 degrees, whereas all of the TA hydraulics are 50 degrees between advertised and .050". So, are the TA cams a faster ramp speed? I would say most likely not, as they definitely don't believe in that philosophy. More likely, they have a more linear ramp up to full open, and the Poston cams have the valves open at the low lift area longer, and then yank them open quicker to full lift. You would have to talk to the manufacturer to know what is really going on.
Hello. I appreciate you guys taking time to shed a little light on my cam. When I assemble the motor, I want the right one in my hand. I have had trouble with lifters/cam bearings/oiling in all of my previous BBB's (that was before the awesome BPG and all the info avaliable). I read how the fast ramp cams were hard on valve train and I want to avoid any problems. Thank you for your time.
The difference between .004 & .006 cam lift is usually 4 degrees, slightly more on older designs The comparsion of advertised(must know if .004/.006/.008 lift) to .050 to .200 lift duration is refered to as INTENSITY. Advertised to .050 numbers tell you how fast the valve comes off the seat and how hard it is set back down. Grinders have room to "play" with this area because older profiles were very gentle here. Now grinders are testing the limits of hydrualic tappets and valve trains like never before; thus extreme energy/fast ramp. BUT the main part of the ramp(.050 to .200 to max lift) angle on flat tappet cams is more concrete; limited by TAPPET DIAMETER; there is only so much lift per degree. TA's "high-lift" profiles showed us max lift "over the nose " wasn't the problem because they work fine. I believe it is the advertised to .050 intensity that causes us BUICK guys problems(noise/breakage). I think it has to do with our cams having the smallest base-circle of any engine that I know of, the longest push rods that aren't as thick as they could be flexing and causing harmonics. Not to mention even with optimized valve stem tip heights our rocker arm geometry isn't the best. Steve Walsh
