Is this the proper way to check cam lift (hydraulic lifters) on SBC?? - Team Camaro Tech
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post #1 of 10 (permalink) Old Oct 19th, 14, 07:13 PM Thread Starter
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guillaumeb
 
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Is this the proper way to check cam lift (hydraulic lifters) on SBC??

Hello!

I have a simple question here!

Today, I wanted to check my valve lift to diagnose a problem I have and I'm suspecting the camshaft.

I removed my valve cover and put a dial indicator on the valves retainers and rotated the engine via the crankshaft bolt (sparkplugs removed). I realized that I couldn't check the valve lift that way because I have hydraulic lifters and when under pressure, they discharge slowly and my dial indicator needle drops slowly. So I can't get a good reading that way... about impossible.

The cam manufacturer of my camshaft (Comp cams) also gives the ''lobe lift'' spec, so I decided to remove the rockers and put my dial indicator directly at the tip of the pushrods. I figured that the internal pressure of the dial indicator was not strong enough to compress the hydraulic lifters and that I should get a pretty good reading. (The pressure of the dial indicator is pretty low).

I wanted your opinion if that is a proper way to check the camshaft lobes lift?
The reading i got seems pretty bad if that is the case...

Please let me know!

Have a nice day!

G.b.
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post #2 of 10 (permalink) Old Oct 19th, 14, 09:04 PM
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Bill
 
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Re: Is this the proper way to check cam lift (hydraulic lifters) on SB

Sounds right to me, but not sure if you'd get an incorrect reading if you had faulty lifter. Maybe you could put a "foot" on the bottom of your dial indicator so that it sits on top of the lifter, not into the hydraulic portion.
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post #3 of 10 (permalink) Old Oct 19th, 14, 10:37 PM Thread Starter
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guillaumeb
 
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Re: Is this the proper way to check cam lift (hydraulic lifters) on SB

I understand your point!
I'm actually putting the dial indicator at the top of the pushrod, and the pushrod sits into the hydraulic portion of the lifter.
However, I was thinking that, even if the lifter was faulty, I would still get a correct reading... Am I wrong? the center (hydraulic) portion of the lifter would still travel the same distance if the lifter internals were bad?

I don't know how I could adapt the dial indicator to go downnn trough the cavity of the pushrod to touch only the brim of the lifter?

thanks

g.b.
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post #4 of 10 (permalink) Old Oct 19th, 14, 10:45 PM
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Bill
 
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Re: Is this the proper way to check cam lift (hydraulic lifters) on SB

Yes, you're likely right, but considering how important the information is, I'd want to be sure I wasn't pulling the engine down to remove the cam if only a lifter was failing.
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post #5 of 10 (permalink) Old Oct 20th, 14, 05:01 AM
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kevin
 
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Re: Is this the proper way to check cam lift (hydraulic lifters) on SB

Quote:
Originally Posted by guillaumeber View Post
I understand your point!
I'm actually putting the dial indicator at the top of the pushrod, and the pushrod sits into the hydraulic portion of the lifter.
However, I was thinking that, even if the lifter was faulty, I would still get a correct reading... Am I wrong? the center (hydraulic) portion of the lifter would still travel the same distance if the lifter internals were bad?

I don't know how I could adapt the dial indicator to go downnn trough the cavity of the pushrod to touch only the brim of the lifter?

thanks

g.b.
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post #6 of 10 (permalink) Old Oct 20th, 14, 06:27 AM
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Re: Is this the proper way to check cam lift (hydraulic lifters) on SB

Quote:
Originally Posted by guillaumeber View Post
I understand your point!
I'm actually putting the dial indicator at the top of the pushrod, and the pushrod sits into the hydraulic portion of the lifter.
However, I was thinking that, even if the lifter was faulty, I would still get a correct reading... Am I wrong? the center (hydraulic) portion of the lifter would still travel the same distance if the lifter internals were bad?

I don't know how I could adapt the dial indicator to go downnn trough the cavity of the pushrod to touch only the brim of the lifter?

thanks

g.b.
Your dial indicator should have a little screw on "flat foot" that you can set on the end of the push rod. Most sets have this little foot along with some screw on needle points or bull nose points.
That should be enough to just ride the push rod ball and tell you what you need on one lobe.
I am assuming your indicator is attached to a magnetic base?
You should be reading your cam card measurements , to get total lift , multiply by rocker arm ratio.

Don
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post #7 of 10 (permalink) Old Oct 20th, 14, 11:04 AM Thread Starter
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Re: Is this the proper way to check cam lift (hydraulic lifters) on SB

Hello!

I am indeed using a magnetic base, and I am also using a round flat foot, about 1/4'' wide. That seems to work pretty well.

I can't figure how the dial indicator extensions would really help; the pushrod inside it's cavity acts like an extension by itself.
the extension would be pretty hard to install into the pushrod cavity and it would also sit in the middle of the hydraulic lifter, giving the same results.

Maybe I'm wrong on a point or smthing...

Thanks a lot
g.b.
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post #8 of 10 (permalink) Old Oct 20th, 14, 11:28 AM
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Re: Is this the proper way to check cam lift (hydraulic lifters) on SB

You're going about it wrong.
For this diagnosis, forget precision measurements. You need to LOOK at the bottom of each lifter. Pull the intake, back off each rocker and remove each lifter and look for galling. Be sure to not mix up the lifters. Make sure they go back in the hole they came from. (that's unless you find a bad one of course, then the cam's gotta come out.)

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post #9 of 10 (permalink) Old Oct 20th, 14, 11:39 AM Thread Starter
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Re: Is this the proper way to check cam lift (hydraulic lifters) on SB

Thanks Fred!

I am just trying to avoid removing the intake if I can.. I just put new gaskets there about 2-3 weeks ago... I would like to let them there if there is no problem.

The reading I get are far from ''precision measurments''. On some lobes, I got 0.230'' when the spec is 0.3''....

i will do the test again but pushing on the pushrods before to be sure they sit well on the cam round surface.

thanks
g.b.
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post #10 of 10 (permalink) Old Oct 20th, 14, 03:26 PM
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Re: Is this the proper way to check cam lift (hydraulic lifters) on SB

Lifters have more spring tension than a dial indicator so your golden on the lobe lift measurement being accurate.

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