NEED INFORMATION: CAMSHAFT

[steamgas]

i need help with a 1952 straight 8 engine camshaft..i just checked the cam lobe lift with a dial indicator. it measures .230. the book says it should be .348. could a cam wear that much over the life of the engine or could this be a special grind from a camshaft rebuild shop just to save the cam? the difference is so close to .125 that it makes me think in that direction. i checked 2 other lifters and the are the same lift.

any help will be needed.

steamgas

[Bloo]

Maybe the lift is specified at the valve and you need to multiply by the rocker ratio?

[steamgas]

dear sir

 i just multiplied the rocker arm ratio (1.45)  x .230 and got the sum of .3335 . that is real close to the book spec. if your formula is the correct one to use. it would be too easy at this time to say that the cam is good. i would like to get some more opinions before i say that your formula is sound. thank you so very much for your input. this is what makes this internet site so valuable.

steamgas

[NTX5467]

When a cam is "reground", what they do is make the "base circle" of the cam smaller by machining it down.  But I don't know where you could find that "base circle" dimension in any factory service manual.  By making the base circle smaller, the existing lobe will effectively become taller, compensating for any wear or "hot rod" intents.

 

Lobe lift x rocker arm ratio = Lift at the valve head (or end of the valve stem, for that matter).

 

I suspect that if all of the lobes measure-out close to the same, just normal wear and no real reason to worry about it, from what I know.  And, it might even be within manufacturing tolerances for back when it was built.

 

NTX5467