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Cam Questions????

1K views 3 replies 3 participants last post by  curtis73 
#1 ·
OK so when it comes to cams, im lost. i get the concept, but i don't know how to tell what kind of idle and also what power range it is. my dad gave me this cam that he had for another 454 BBC that he was going to build, but like most things it just sat around, so i came a 454 BBC myself and he just handed it over but all he knew is what the tag said. so the tag said that the Duration 286/296, Lift .540/.540. and the lobe separation is 114 degrees. so can anyone give me an idea of what im looking at here. sorry for just rambled on. any thing will help thanks.
 
#2 ·
FAIR IDLE, MODERATE PERFORMANCE USAGE, GOOD MID-RANGE HP, MILD BRACKET RACING, AUTO TRANS W/2500+ CONVERTER, 3200-3600 CRUISE RPM, 9.5 TO 11.5 COMPRESSIONRATIO ADVISED. BASIC RPM 2500-5500

Recommended RPM range with matching components
Minimum RPM 2400
Maximum RPM 6200
Valve Float 6800

This description is from Crane for a cam that is very close to the timing figures on the cam you have. Main difference is the Crane cam is cut on 112 degree lobe separation angle. Your cam will be close to this description though.
 
#3 ·
re

ok so im probably making this more difficult than it really is but there are two sets of numbers. on is an advertised and the other is actual.

the advertised is Duration 286/296, Lift .540/.540. and the lobe separation is 114 degrees.

and the actual is Duration 228/238, and the lift is the same.

so i dont know if that makes any difference at all. but then again im still learnin
 
#4 ·
Advertised duration is measured at either .004 or .006" lift depending on the manufacturer. In some rare cases, they'll advertise seat-to-seat numbers. The other one is the duration measured at .050" lift. That is to say that the lifter is raised greater than .050" for a total of 228 crank degrees before it falls back down below .050". They publish both because its an indicator of how fast the ramps are. The closer those two numbers are, the faster the angle of the ramp.

Both are equally important numbers, but most hot rodders deal with what we might call "@ 50" numbers.
 
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