Pennock's Fiero Forum
  Technical Discussion & Questions
  Explain to me how the hydraulic lfters work please.

Post New Topic  Post A Reply
Email This Page to Someone! | Printable Version


next newest topic | next oldest topic
Explain to me how the hydraulic lfters work please. by fierofinder
Started on: 09-14-2013 09:13 PM
Replies: 12 (347 views)
Last post by: fierofinder on 09-16-2013 10:34 AM
fierofinder
Member
Posts: 629
From: Battle Ground, WA
Registered: Apr 2007


Feedback score: (1)
Leave feedback

Rate this member

Report this Post09-14-2013 09:13 PM Click Here to See the Profile for fierofinderClick Here to Email fierofinderSend a Private Message to fierofinderEdit/Delete MessageReply w/QuoteDirect Link to This Post
I have my lower intake off so I'm studying how the lifter and springs work as I hand crank the engine. The lifter moves in two ways. The whole thing moves up and down and the center moves a tiny bit within that. Now when adjusting valves I am assuming it is the center part that you want to adjust half way. This is where I get confused. I adjust the valve just to zero lash no farther and then crank the engine by hand and the center looks as if it bottoms out. It wont go down any farther. So with one and a half turns past zero lash it gets to that point a lot faster. What I'm thinking is it isn't really bottomed out, it just has to much hydraulic pressure to go down any farther. The entire lifter will continue to push up but the center doesn't go down any farther. Would heavier duty springs be my solution to push back on the valve harder.
IP: Logged
PFF
System Bot
fierofinder
Member
Posts: 629
From: Battle Ground, WA
Registered: Apr 2007


Feedback score: (1)
Leave feedback

Rate this member

Report this Post09-14-2013 09:23 PM Click Here to See the Profile for fierofinderClick Here to Email fierofinderSend a Private Message to fierofinderEdit/Delete MessageReply w/QuoteDirect Link to This Post
Also this is my spring at full lift with the 1 1/2 turns past zero lash. Almost no room left is this ok?

IP: Logged
trotterlg
Member
Posts: 1378
From: WA
Registered: Aug 2011


Feedback score: (2)
Leave feedback

Rate this member

Report this Post09-14-2013 10:54 PM Click Here to See the Profile for trotterlgClick Here to Email trotterlgSend a Private Message to trotterlgEdit/Delete MessageReply w/QuoteDirect Link to This Post
The lifter (the part that rides on the cam) has a piston in it with a little spring pushing up on it. There is a very small hole in the side that leads to the pressurized oil passage that oils the lifter. The oil pushes up on the piston to take the lash out of the valves. In the bottom of the little cup the push rods go in there is a little ball that plugs the hole you see in the cup. If you want to get the piston to go all the way to the bottom of the lifter you have to get the oil out of the bore of the lifter. Take a little wire and depress the ball while pushing down on the little cup, oil will come out the hole and the piston will go to the bottom. This is the piston you want about half way down the bore in the lifter. You can only adjust the rockers when the valves are closed and the lifter is all the way down. The spring in the lifter will hold the piston up, but not much pressure on it, so you have to take care you are not pushing it down. Take all the slack out the valve system and when it is just barely starting to push down the little cup, count the turns down on the valve adjustment, (avout 1 turn or so. Hope this makes a little sence to you. Larry
IP: Logged
fierofinder
Member
Posts: 629
From: Battle Ground, WA
Registered: Apr 2007


Feedback score: (1)
Leave feedback

Rate this member

Report this Post09-15-2013 12:28 AM Click Here to See the Profile for fierofinderClick Here to Email fierofinderSend a Private Message to fierofinderEdit/Delete MessageReply w/QuoteDirect Link to This Post
this is helpful. I know about adjusting valve lash, but every time I have done it I couldn't see the lifters. Now that I can see the lifters while adjusting it, it seems wrong. I would think it would go in further. From zero lash it would only take two full turns to go down as far as it does. I was expecting three+. What I would like to be able to do is see how many turns it takes top to bottom so that I have halfway exactly. So I should start by getting the oil out and then counting the turns. I have 1.6 rocker with arp studs that is why I'm trying to look into this. According to a mathematical solution that someone helped me out with in the past it ends up being about one and a half turns. Also If someone could chime in on the spring. How far can the spring compress before it is too far.
IP: Logged
trotterlg
Member
Posts: 1378
From: WA
Registered: Aug 2011


Feedback score: (2)
Leave feedback

Rate this member

Report this Post09-15-2013 12:50 AM Click Here to See the Profile for trotterlgClick Here to Email trotterlgSend a Private Message to trotterlgEdit/Delete MessageReply w/QuoteDirect Link to This Post
To see the pistons go clear to the bottom you need to let the oil out of them. You really don't need to do them all, the are all the same. They will slowly blead down by them selves, so I would just do a couple and see what happens. Larry
IP: Logged
fierofinder
Member
Posts: 629
From: Battle Ground, WA
Registered: Apr 2007


Feedback score: (1)
Leave feedback

Rate this member

Report this Post09-15-2013 01:29 AM Click Here to See the Profile for fierofinderClick Here to Email fierofinderSend a Private Message to fierofinderEdit/Delete MessageReply w/QuoteDirect Link to This Post
Great thank you, that actually helps a lot.. Now does any one have some input on the spring.
IP: Logged
Patrick
Member
Posts: 30189
From: Vancouver, British Columbia, Canada
Registered: Apr 99


Feedback score: (1)
Leave feedback





Total ratings: 443
Rate this member

Report this Post09-15-2013 01:35 AM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by fierofinder:

Now does any one have some input on the spring.


IMO, as long as the springs don't bind at full lift, they should be fine.

Get a second opinion though.

IP: Logged
trotterlg
Member
Posts: 1378
From: WA
Registered: Aug 2011


Feedback score: (2)
Leave feedback

Rate this member

Report this Post09-15-2013 11:25 AM Click Here to See the Profile for trotterlgClick Here to Email trotterlgSend a Private Message to trotterlgEdit/Delete MessageReply w/QuoteDirect Link to This Post
The springs look fine, they have a ways to go yet, so life it good. Larry
IP: Logged
katatak
Member
Posts: 7136
From: Omaha, NE USA
Registered: Apr 2008


Feedback score:    (8)
Leave feedback





Total ratings: 82
Rate this member

Report this Post09-15-2013 08:35 PM Click Here to See the Profile for katatakSend a Private Message to katatakEdit/Delete MessageReply w/QuoteDirect Link to This Post
Keep in mind that the thread pitch on the ARP studs may be different than a stock stud - therefore, 1.5 turns may be too much.

Also - if you are truly at zero lash, the popet should not be "depressed" any. It does not take much to start moving the popet when trying to set zero lash. Especially if the lifters are partially deflated.

[This message has been edited by katatak (edited 09-15-2013).]

IP: Logged
fierofinder
Member
Posts: 629
From: Battle Ground, WA
Registered: Apr 2007


Feedback score: (1)
Leave feedback

Rate this member

Report this Post09-15-2013 10:58 PM Click Here to See the Profile for fierofinderClick Here to Email fierofinderSend a Private Message to fierofinderEdit/Delete MessageReply w/QuoteDirect Link to This Post
This is the formula that I was given awhile back to get the new turns past zero lash. Messing with it today however I did not get any of the lifters to travel more than two full turns so its seems as halfway is only one turn not one and a half.

If your rocker arms are a different ratio than stock, then you should correct for that also:

X = 1.5 x (Poem / Pnew) x ((Roem + 1) / (Rnew + 1))

Where:

X = New optimum number of turns of the adjusting nut past zero lash
1.5 = OEM specification (number of turns)
Poem = OEM thread pitch (inches or mm)
Pnew = new thread pitch (inches or mm)
Roem = OEM rocker ratio
Rnew = new rocker ratio


Edit: To correct formula term for rocker arm ratios
IP: Logged
trotterlg
Member
Posts: 1378
From: WA
Registered: Aug 2011


Feedback score: (2)
Leave feedback

Rate this member

Report this Post09-16-2013 12:20 AM Click Here to See the Profile for trotterlgClick Here to Email trotterlgSend a Private Message to trotterlgEdit/Delete MessageReply w/QuoteDirect Link to This Post
If there is oil in the lifters then you will not get them to travel full down. To get full travel on the little pistons you need to bleed them down by depressing the little ball in the bottom of the socket while pushing the piston in. Larry
IP: Logged
PFF
System Bot
Slowbuild
Member
Posts: 251
From: British Columbia
Registered: Nov 2009


Feedback score: N/A
Leave feedback

Rate this member

Report this Post09-16-2013 02:20 AM Click Here to See the Profile for SlowbuildSend a Private Message to SlowbuildEdit/Delete MessageReply w/QuoteDirect Link to This Post
One of the things I have witnessed is a lifter staying 'pumped up'. It freaked me out because you go to 0 lash, then 1.5 turns and the valve open partially because the lifter piston is hardened up...So I'm like, that can't be right looking at the rocker move.

It is though...

The better way is to drain the lifter oil as described above, then what should happen is find 0 lash, add the 1.5 and there should be some travel left in the lifter piston...it's a bit soft until it pumps up the first time it is run. Some argue .5 turns or 1.0 turns...doesn't really seem to matter as ling as you're in the travel of the lifter piston somewhere.

Chay
IP: Logged
fierofinder
Member
Posts: 629
From: Battle Ground, WA
Registered: Apr 2007


Feedback score: (1)
Leave feedback

Rate this member

Report this Post09-16-2013 10:34 AM Click Here to See the Profile for fierofinderClick Here to Email fierofinderSend a Private Message to fierofinderEdit/Delete MessageReply w/QuoteDirect Link to This Post
I'm pretty sure I had all the oil out of the ones I tried. I could see the oil coming out the side. I worked at it for awhile to be sure.
IP: Logged

next newest topic | next oldest topic

All times are ET (US)

Post New Topic  Post A Reply
Hop to:

Contact Us | Back To Main Page

Advertizing on PFF | Fiero Parts Vendors
PFF Merchandise | Fiero Gallery | Ogre's Cave
Real-Time Chat | Fiero Related Auctions on eBay



Copyright (c) 1999, C. Pennock