Measuring a cam lobe????

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xLURKxDOGx

xLURKxDOGx

"An angel fat, at satan's feast"
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I picked up a few NOS purple cams and they do not have a marking on them whatsoever so I’m trying to determine what I have. Any info or calculations to determine this would be welcomed. One set is intake, the other exhaust.

Thanks,
Jake

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My numbers are coming up with .492 with 1.5 rockers. I’ve got a base circle of 1.272 and then 1.578 across the lobe.


Jake
 
How did you get .492? Subtract base circle from lobe and multiply by rocker ratio for valve lift.
(1.578-1.272)x1.5=.459
 
TT5.9mag said:
How did you get .492? Subtract base circle from lobe and multiply by rocker ratio for valve lift.
(1.578-1.272)x1.5=.459
Click to expand...
Not sure, bad math? You have any idea what cam it could be?

Jake
 
My fast math shows you have 1.558 and 1.277 @ 1.5 ratio is .4215 lift.(I have to edit this), NOT 1.277 is 1.227 for a lift of .4965. Regardless the fisher-price measuring stick only shows one thing... the cam is purple!
 
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Here's how. Measure the base circle. That's STRAIGHT across the SIDES of the lobe. Write that number down. That's the base circle number. Now measure the WHOLE lobe from the BOTTOM of the base circle to the PEAK of the lobe. Write that number down. Now, divide that first number you got from the sides of the lobe in half. Next, subtract THAT number from the whole lobe measurement. That's the lobe lift. Now, finally multiply THAT number by "whatever" rocker ratio. 1.5 is "usually" it for small and big blocks unless you're running 1.6. Does that make sense?
 
RustyRatRod said:
Here's how. Measure the base circle. That's STRAIGHT across the SIDES of the lobe. Write that number down. That's the base circle number. Now measure the WHOLE lobe from the BOTTOM of the base circle to the PEAK of the lobe. Write that number down. Now, divide that first number you got from the sides of the lobe in half. Next, subtract THAT number from the whole lobe measurement. That's the lobe lift. Now, finally multiply THAT number by "whatever" rocker ratio. 1.5 is "usually" it for small and big blocks unless you're running 1.6. Does that make sense?
Click to expand...
Yeah, my calipers are hard to read I’ll get a digital set and see what numbers I come up with.

Jake
 
xLURKxDOGx said:
Not sure, bad math? You have any idea what cam it could be?

Jake
Click to expand...


TT5.9mag said:
How did you get .492? Subtract base circle from lobe and multiply by rocker ratio for valve lift.
(1.578-1.272)x1.5=.459
Click to expand...


TT5 is correct on the lift of this lobe, but you need to measure another lobe next to that one for us to even be able to guess what it can be...


We need to know if it's an intake or exhaust lobe...

This is my best guess with the information that you have posted so far:

Duration 268/272, Lift .450/.455, Chrysler, 273, 318, 340, 360
 
krazykuda said:
Measure two lobes next to each other just like you did, across the base circle, and then across the lobe and give us the numbers...
Click to expand...
Thanks for the response, I’ll get some numbers tomorrow.

Jake
 
I gotta say....... that’s the most screwed up dial face I’ve ever seen.

It took me a few minutes before I caught on........ the outer range isn’t like most dial calipers.
It’s not .001”....... it’s .010”.
One revolution per inch.

So, the first pair of numbers is 1.265 from 1.580 ...... .315 lobe lift = .4725 lift.

If both intake and exhaust lobes are the same, it’s probably a .474 cam.
 
PRH said:
I gotta say....... that’s the most screwed up dial face I’ve ever seen.

It took me a few minutes before I caught on........ the outer range isn’t like most dial calipers.
It’s not .001”....... it’s .010”.
One revolution per inch.

So, the first pair of numbers is 1.265 from 1.580 ...... .315 lobe lift = .4725 lift.

If both intake and exhaust lobes are the same, it’s probably a .474 cam.
Click to expand...
Thanks for responding. Yeah, im going to get a new pair because it took me an hour to figure out what i was looking at.

Jake
 
zeroed on the base and just roll around on v-blocks
here's the other.....

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0.00"
 
xLURKxDOGx said:
Thanks for responding. Yeah, im going to get a new pair because it took me an hour to figure out what i was looking at.

Jake
Click to expand...

Now that I see the graduations, it should be fine for what you’re doing.

Just took me a minute to understand what I was looking at.

Had it been in my hand, I would have seen it was one revolution per inch...... then I’d have “gotten it” right away.

I remembered I actually have a cheap plastic one that reads similarly that I use to use for going to the junk yard, etc.
 
Funny I looked at lurks numbers and didn’t even look at the dial. Nice catch PRH.
 
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