question about setting hydraulic valves
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
...but this is not how this is done. The rocker should be loosened until the pushrod rotates freely...then tightened slowly until the first hint of drag is felt...backing off and re-tightening a bit if needed to feel for zero lash.
The push is against the spring...so it's really not going to "back off" after a minute. There's no bleed-down - if the engine isn't running then there's no pressurized oil to push the cup up.
The push is against the spring...so it's really not going to "back off" after a minute. There's no bleed-down - if the engine isn't running then there's no pressurized oil to push the cup up.
Some lifters still have oil locked in and some don't.
I think your method might work better for the inexperienced if all rockers were backed off,spin the engine to pump the lifters up and then adjust.
If your talking about adjusting in an un-primed motor , then the person is going to have to feel the cup spring.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
That's where the "experienced" feel of the cup spring comes in.
Some lifters still have oil locked in and some don't.
I think your method might work better for the inexperienced if all rockers were backed off,spin the engine to pump the lifters up and then adjust.
If your talking about adjusting in an un-primed motor , then the person is going to have to feel the cup spring.
Some lifters still have oil locked in and some don't.
I think your method might work better for the inexperienced if all rockers were backed off,spin the engine to pump the lifters up and then adjust.
If your talking about adjusting in an un-primed motor , then the person is going to have to feel the cup spring.
The cup can't move higher than the top of it's travel, no matter what. If pushed down, even if the lifter has oil in it - the spring will push it back to the top of the lifter. Zero lash will be when the lifter is at the top of it's travel - either by the spring or by any residual oil pressure.
If what you note is happening, then the person isn't feeling for zero lash but is way, way over-tightening...which is pretty hard to do when you're just feeling from a loose pushrod to a hint of friction.
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
That's where I think newbies run into a problem, they don't detect that "first hint of drag",then they end up with the lifter cup at the bottom of its travel thinking the bottom is the "drag".
If you or someone experienced were there to point out "the correct point of drag" ,with the cup at the top,I'm sure they would remember it for a lifetime.
I've had many a car towed in with all the lifters bottomed out.
EDIT-Just for the record-I use the spin method.
If you or someone experienced were there to point out "the correct point of drag" ,with the cup at the top,I'm sure they would remember it for a lifetime.
I've had many a car towed in with all the lifters bottomed out.
EDIT-Just for the record-I use the spin method.
Last edited by ...Roger...; Aug 26, 2011 at 05:19 PM.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
That's where I think newbies run into a problem, they don't detect that "first hint of drag",then they end up with the lifter cup at the bottom of its travel thinking the bottom is the "drag".
If you or someone experienced were there to point out "the correct point of drag" ,with the cup at the top,I'm sure they would remember it for a lifetime.
I've had many a car towed in with all the lifters bottomed out.
If you or someone experienced were there to point out "the correct point of drag" ,with the cup at the top,I'm sure they would remember it for a lifetime.
I've had many a car towed in with all the lifters bottomed out.
Someone cranking down until they have the lifters flat is someone that has no idea how to adjust valves...regardless of how they find zero lash.
This branding of the twist method as unusable by newbies just doesn't hold water and I have yet to hear anything specific to the contrary. So - do what I did; the next time you're going to help someone with it, talk them through both and see what works. If they actually find the twist method is harder - then post about it
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
One of the exercises I remember from HS automotive was setting O lash on a dry lifter,about 1/2 failed it the first time.
The guys that failed ,probably used a set of mics like a C clamp.
The guys that failed ,probably used a set of mics like a C clamp.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
I do a lot of "assisted" builds where the guy wants to build his own engine and I just keep him from making mistakes. It always starts with learning precision measuring...and for some folks...that can take a long, long time.But my point is newbie does not automatically equal "Bubba".
