Thread: Deciding which Lifter a motor has

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How can you determine if a motor has hydraulic or solid lifters? Is there a way on a small block chevy without pulling the intake and removing the lifter?

Back off the rocker adjustment so there is a few thousandths play in the valve train. (You may have to do this a couple of times to allow any residual hydraulic pressure to bleed off - if the lifters are hydraulic.)

Rock the rocker back toward the pushrod side and see if the pushrod goes down.
It should go at least .060.
If it does depress this indicates the lifter is hydraulic.
If it does not depress, that would indicate a solid lifter.

If it's a fairly common and unmolested SBC more than likely it's a hydraulic lifter set-up.

This is a crate motor from who I don't know. I was told it has an RV cam and it does idle pretty rough. It has roller rockers with lock screws on the rocker bolts.

The definition of an RV cam is fairly high lift, fairly short duration and wide lobe seperation angle (112-114) for smooth idle and high manifold vacuum.

If your motor idles rough, it's not an RV cam. Some people just use that terminology because they don't know any better. The rough idle results from fairly long duration and a narrower lobe separation angle to allow the motor to breathe at higher rpm's.

An RV cam will be effective from idle to maybe 4,500 rpm's. If you're getting a rough idle, your cam is probably effective from about 2,000-2,500 rpm's to about 5,500 or 6,000 rpm's. I can't be specific not seeing the cam card, I'm just giving you an overview.

The locks on the rocker nuts are the way the aftermarket suppliers address keeping the nuts tight. Chances are about 99.9% that you have hydraulic lifters in the motor.

OK! I pulled a rocker off and used a wood dowel and pushed down on the pushrod and it didn't move. The motor has not ran since yesterday afternoon. On a hydraulic lifter I would think it would compress at least 1/8", or enought to be noticeable. When I losened the rocker nut it did take a full turn to losen the rocker. My main problem is that the motor is hard to start when its cold and the valve train makes noise, even hot. Which doesnt make sense because if the lifters were solid they would quit down once the motor came to temp. On a 24 pitch thread the lead per therad is .041, which would mean the the valves are staying open some fraction of that. And after all this why would the valve train make noise if the motor did have solids and they were adjusted to tight? Thanks for all the help.

Solid lifters, by their nature are a little noisy.
Specially so if they are out of adjustment.

Originally posted by techinspector1
The definition of an RV cam is fairly high lift, fairly short duration and wide lobe seperation angle (112-114) for smooth idle and high manifold vacuum.

If your motor idles rough, it's not an RV cam. Some people just use that terminology because they don't know any better. The rough idle results from fairly long duration and a narrower lobe separation angle to allow the motor to breathe at higher rpm's.

An RV cam will be effective from idle to maybe 4,500 rpm's. If you're getting a rough idle, your cam is probably effective from about 2,000-2,500 rpm's to about 5,500 or 6,000 rpm's. I can't be specific not seeing the cam card, I'm just giving you an overview.

The locks on the rocker nuts are the way the aftermarket suppliers address keeping the nuts tight. Chances are about 99.9% that you have hydraulic lifters in the motor.

Thank you Mr. Techinspector for your post.

I've had more than a few tell me their engines are running RV cams.
I don't try to embarrass people, but sometimes I just have to ask why they would put such a low rpm cam in a lightweight car.

After the blank look, the next thing that happens is the 'walkaway.'

Kinda goes along with the guys who claim to have built a car that's been running around town for quite a while and folks know the new owner was not the builder.

Must be the competitiveness of men.
Either that or they just like to lie....

"After the blank look, the next thing that happens is the 'walkaway.'"