Is this the proper way to check cam lobes lift (with hydraulic lifters) on chevy SBC?
#1
Is this the proper way to check cam lobes lift (with hydraulic lifters) on chevy 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.
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.
#2
Unless you remove one of the valve springs and install a light spring your method should give you the correct lobe lift.
#3
Le Mans Master
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.
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.
#4
Humm, Yeah! I completly forgot to push down on the pushrods when doing the test... maybe that's the reason of my bad readings..! only 2-3 lobes on the 8 I checked were near the specs... the other were muchh lowerr!
thanks!
g.b.
thanks!
g.b.
#5
Le Mans Master
Member Since: Jul 2006
Location: charlotte north carolina
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I thought that when the lifter rises into the bore, the fill hole is closed(by contact with the bore hole) and it will not compress. The "adjustment" is when the lifter is on the base circle and the fill hole is exposed to engine oil pressure. Please correct me if I'm wrong!
#6
That seems right to my understanding too, but when I'm checking the valve lift with my dial indicator, the lifter has to be at it's bottom position at some point (on the base circle) and then the oil drips out...giving bad readings...
g.b.
g.b.
#7
Burning Brakes
I thought that when the lifter rises into the bore, the fill hole is closed(by contact with the bore hole) and it will not compress. The "adjustment" is when the lifter is on the base circle and the fill hole is exposed to engine oil pressure. Please correct me if I'm wrong!
With the motor stopped, no (static scenario).
With the motor stopped the oil has time to flow through the openings created because of the tolerances needed both inside the lifter and between the lifter and the block.
#8
Le Mans Master
Listen to an 80's vintage Subaru for reference. They regularly had lifters go bad and clacked to beat he** at start and/or while idling.
#9
Maybe my lifters are all bad then ... or maybe to much play between the lifters and their bore... but my dial indicator indeed show a little drop of the lifters on the indicator... a slow leak in the lifters... but the engine did not clack or make noise... fortunatly...
thanks
g.b.
thanks
g.b.
#10
Burning Brakes
Maybe my lifters are all bad then ... or maybe to much play between the lifters and their bore... but my dial indicator indeed show a little drop of the lifters on the indicator... a slow leak in the lifters... but the engine did not clack or make noise... fortunatly...
thanks
g.b.
thanks
g.b.
That's normal if you have the regular valve springs in it. That way the oil is slowly pushed out of the lifters.
#11
I did using regular springs! That would explain the slow leak.
I figured that I was better of taking the reading directly on the top of the push rods instead of the valve itself to avoid buying and installing all checker springs and then back to regular springs.
thanks
g.b.
I figured that I was better of taking the reading directly on the top of the push rods instead of the valve itself to avoid buying and installing all checker springs and then back to regular springs.
thanks
g.b.
#12
Melting Slicks
...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...
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...
As determined, this is only cam lobe lift (from the base circle to the peak of the lobe); valve lift will be this value times the rocker ratio when the rocker is replaced. For solid lifters, it will be times the rocker ratio less the valve lash.