purpleshaft cam question

[72satteldog]

Hey guys, anyway to tell lift and duration on what i know is a purpleshaft cam in my 440, engine was a rebuilt when i bought the car and the previous owner was not sure on the spec, maybe a part # on the cam? Any info will help, thanks

 

[mopar367]

Is there not usually a number on the end of the cam where the timing gear bolts on? Or I guess you could always take it out and measure the lobes, not that I would just wanna remove it to see what kind it is.

 

[Red63440]

Mic the cam lobe from the top of point to the heel (up and down), then mike it 90 degrees from that (sideways). Subtract the small dimension from the large, and multiply that figure by the rocker arm ratio (1.5, 1.6). That will give you gross valve lift. If the difference between the two measurements was 0.298 then you would multiply that by the rocker ratio you are running in your engine, say 1.5.

1.5 x 0.298 = 0.477

If the cam is in the car then I'm not sure it can be measured. If its just a curiosity then don't let it bother you if you are heppy with how its running. If you are going to rebuild then wait till the engine is out and then check the cam.

 

[Meep-Meep]

You can put a 1" travel dial indicator on the valve spring retainer and measure the lift as you roll the engine over. Since you know it's a purple shaft the lift reading will give it away.

 

[67 B-body]

You can put a 1" travel dial indicator on the valve spring retainer and measure the lift as you roll the engine over. Since you know it's a purple shaft the lift reading will give it away.

X2...
Very simple way to do it! You can also put a degree wheel on the crank to measure duration from .05" lift to .05" before close.

 

[72satteldog]

appreciate the info, thinking of yanking the motor and doing some work on it, guess i can check it then. will sure use some more of the expert advice in this forum during my rebuild, thanks again