Cam Lift Off by .005
05-23-2004, 02:46 PM
#1
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Car: 84 Z28 Convertible 2 Seater
Engine: Dart Little-M SBC 400
Transmission: Pro-built Automatics 700R4
Axle/Gears: Strange Engineering 3:73
Cam Lift Off by .005
I degreed my cam using a Summit degree wheel,dial indicator, and piston stop. However I have check the lift on # 1 and # 6 lifter (USING SOLID LIFTER) and my lift is not where the manfacture says it should be. The cam card says EX-0.353.
I had 0.352 (Not bad at all) however on the intake side I was only able to get 0.345 max lift and the card say it should have 0.350. which will give me .005 less than what is advertised. I have recheck this over 10X and still in the same figures from .345-.3455 everytime. I was expecting to have 525/530 gross lift but now I will have 517.5/528. Which also reduce my net lift to 502/491.
Looking through some of Lunati other popular cam I thought I could have received the wrong cam. The reason I say this is his SB276/284F10, 243/251 at .050, .518/.530 valve lift, and 110 LSA. Which is the exact same lift that I came up with.
The 517.5 lift on the intake is identical to his 276/284. But my cam card and Lunati box says I should have the 280/284F10.
I setup the wheel and dial indicator to recheck my duration and here is what I have. The 11" degree wheel take alot of guessing out of the equation.
Intake:
17.5 open
49.0 close
+ 180 = 246.5* Cam Card Says: 247* @.050
Lift = 0.345 x 1.5 = 517.5 Cam Card Says: .525 lift
Exhaust
12
60
+ 180 = 252* Cam Card Says: 251* @.050
Lift = .352 x 1.5 = 528 Cam Card Says: 530 Lift
I also used a different lifter. My intake lift is shorter than whats advertised.
How will this affect performance and loss of horsepower across the power band?
I had 0.352 (Not bad at all) however on the intake side I was only able to get 0.345 max lift and the card say it should have 0.350. which will give me .005 less than what is advertised. I have recheck this over 10X and still in the same figures from .345-.3455 everytime. I was expecting to have 525/530 gross lift but now I will have 517.5/528. Which also reduce my net lift to 502/491.
Looking through some of Lunati other popular cam I thought I could have received the wrong cam. The reason I say this is his SB276/284F10, 243/251 at .050, .518/.530 valve lift, and 110 LSA. Which is the exact same lift that I came up with.
The 517.5 lift on the intake is identical to his 276/284. But my cam card and Lunati box says I should have the 280/284F10.
I setup the wheel and dial indicator to recheck my duration and here is what I have. The 11" degree wheel take alot of guessing out of the equation.
Intake:
17.5 open
49.0 close
+ 180 = 246.5* Cam Card Says: 247* @.050
Lift = 0.345 x 1.5 = 517.5 Cam Card Says: .525 lift
Exhaust
12
60
+ 180 = 252* Cam Card Says: 251* @.050
Lift = .352 x 1.5 = 528 Cam Card Says: 530 Lift
I also used a different lifter. My intake lift is shorter than whats advertised.
How will this affect performance and loss of horsepower across the power band?
05-23-2004, 03:00 PM
#2
TGO Supporter
you're checking it at the lifter right? .005 sounds like a lot to be off. i'd swap lifters around, check a differant set of lobes. if it were at the rocker tip i could see tolorances stacking up on you to make for a .005 differance.
05-23-2004, 05:09 PM
#4
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Car: 84 Z28 Convertible 2 Seater
Engine: Dart Little-M SBC 400
Transmission: Pro-built Automatics 700R4
Axle/Gears: Strange Engineering 3:73
I did this at the Lifter and its a Solid cam. I tried switching lifters and another cylinder # 6 with the exact same results that can be found in the first post.
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