Thread: Hydraulic lifters

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What is the average force in lbs. it takes to compress a hydraulic lifter? Should I be able to push on the pushrod and compress the lifter after the motor has not ran for a day?

You know, this is one of those things, that after building motors for over 40 years, I don't know.

I'm thinkin' that with the lifters pumped up, they're gonna stay pumped up and you won't be able to push the plunger down in the lifter body. If you could, the motor would rattle every time you went out to start it until the lifters pumped back up again.

For you other board members: he's trying to determine if the motor has solid or hydraulic lifters in it. Can somebody smarter than I am please help him out.

If I were faced with this dilemma, I think I'd get my hands on a borescope like the firearms guys use, pull a pushrod out and go looking for a snap ring in the top of a lifter. Or, if I were younger with good eyes, I might be able to see a snap ring with a good strong light.

Come on guys, there has to be a simple way to do this.

I thought about checking for a snap ring but in looking at lifter and cam sites it apears that solid lifters also have a snap ring. Maybe you can shed some light on this fact. Since the motor has not ran for a few days I would think that the oil back pressure is zero and that I should be able to compress the lifter. I know on a motor with many miles I have adjusted the rockers and was able to compress the lifter by rocking the rocker. Another question would be is even on a high performance lifter is the spring at the bottom of the lifter body the same Lbs. spring as a stock lifter. All this seems thivial but the only alternative is to pull the intake. yuck...yuck!!

Denny, what would be the amount of pressure needing to be applied and how long would you have to hold that pressure to bleed down a typical SBC hydraulic lifter??

O.K. 26thiboy, it looks like you'll have to call around and find a shop that has the tool Denny mentioned and ask if they can perform a leak-down test on just one lifter.

If you find no takers, then rig up a long bar for leverage with some sort of cobbled up fixture and hold pressure on the back of a rocker for a minute or two. Make certain the valve is closed so the lifter is on the base circle of the cam. I think I'd make my pivot ratio about 6:1, so that applying about 50 lbs of pressure on the end of the bar would equal 300 lbs at the rocker. If you're unsure of what 50 lbs feels like, use your torque wrench on a bolt to get a feel for it. Or, you could build your fixture with a 12:1 ratio and apply 25 lbs of force to it. Whatever. You get the idea.

Guys thanks for all your help on both threads. I took a small rod and put it along side the pushrod and set a dial indicator on top. I then set the pushrod at zero backlash. I tightened the rocker nut 1/4 turn and waited. It took about 90 seconds and the indicator read .009. I then added another 1/4 turn and in less than 60 seconds it read .020. So, I have hydraulic lifters. Unfortunately #1 exhaust and #5 intake lifters I can rock the rocker back and compress the lifter maybe .060. Which is why I started this campaign, the valve train isw making noise cold or hot. Again thanks for the help.

Originally posted by 26thiboy
Guys thanks for all your help on both threads. I took a small rod and put it along side the pushrod and set a dial indicator on top. I then set the pushrod at zero backlash. I tightened the rocker nut 1/4 turn and waited. It took about 90 seconds and the indicator read .009. I then added another 1/4 turn and in less than 60 seconds it read .020. So, I have hydraulic lifters. Unfortunately #1 exhaust and #5 intake lifters I can rock the rocker back and compress the lifter maybe .060. Which is why I started this campaign, the valve train isw making noise cold or hot. Again thanks for the help.

Thanks hiboy, now we all know the simple way to find out.