Previous Thread
Next Thread
Print Thread
Page 2 of 3 1 2 3
Re: Optimum lifter preload [Re: fastmark] #2591356
12/13/18 04:08 PM
12/13/18 04:08 PM
Joined: Mar 2011
Posts: 3,055
Michigan
A
A727Tflite Offline
master
A727Tflite  Offline
master
A

Joined: Mar 2011
Posts: 3,055
Michigan
A question for fast - in theory, wouldn’t weaker valve springs allow quicker and more violent lifter separation/pump up?

Wouldn’t weaker valve springs take longer to “pump down” the plunger versus a stronger spring?

Re: Optimum lifter preload [Re: A727Tflite] #2591357
12/13/18 04:10 PM
12/13/18 04:10 PM
Joined: Jun 2008
Posts: 3,913
usa
L
lewtot184 Offline
master
lewtot184  Offline
master
L

Joined: Jun 2008
Posts: 3,913
usa
Originally Posted By Transman
I see this preload topic brought up and battered to death with opinions and such.

Question for those that may have checked.
How much plunger travel exists on a production Chrysler lifter?
How much plunger travel exists on a late model aftermarket lifter?

Reason I ask.

The service manual calls out .060” - .210” dry lash.
That equates to .040” - .140” plunger preload.

If you have production level plunger travel - your engine should not run poorly, idle poorly, perform poorly with this preload.

I ran production juice lifters in Stock Eliminator in the 70’s with a GK cam, production pushrods and rockers and never floated a valve, broke parts, etc. I kept my preload at .060”. No issues for 5 years using the same parts without replacement. Of course I only spun it 6K back then but it never failed me.
all the tappets I've measured had .200+ plunger travel. this does not include any of the race tappets, just factory or OEM replacement.

Re: Optimum lifter preload [Re: fastmark] #2591369
12/13/18 04:23 PM
12/13/18 04:23 PM
Joined: Jun 2008
Posts: 3,913
usa
L
lewtot184 Offline
master
lewtot184  Offline
master
L

Joined: Jun 2008
Posts: 3,913
usa
heavier springs do allow the tappet to resist pump up. like anything else there's pros and cons to heavier springs.

I think the .020"-.040" thing came out of the mid to late '60's. I remember the chevy guys reducing their tappet pre-load by backing off the rocker. I don't think any of us back then truly understood pre-load; we were just trying to get more rpm by eliminating pump-up. a lot of the hobby is monkey see-monkey do so the ford and mopar guys thought they had to do the same thing; me included. I can't say that I gained much, if anything, by doing this. if I remember correctly valve spring changes meant more than tappet adjustments. now I just put the plunger somewhere around mid travel and just let the juice lifter be what it is.

Re: Optimum lifter preload [Re: A727Tflite] #2591435
12/13/18 06:20 PM
12/13/18 06:20 PM
Joined: Jan 2003
Posts: 6,363
Abilene, Texas
F
fastmark Offline OP
master
fastmark  Offline OP
master
F

Joined: Jan 2003
Posts: 6,363
Abilene, Texas
Originally Posted By Transman
Fastmark - how did you determine how much preload you have ? What method did you use ?


I used a dial indicator on the tip of the rocker by the pushrod and tightened the rocker stands until the pushrod had zero preload. The cam was on the base circle, of coarse. I tightened the bolts till the shaft was tight to the stands and then read the indicator. Comp had a different way in some instruction I had once. They said to mark the pushrod at zero preload and and then tighten the shafts and mark again. Measure the difference and you have your preload. Both methods came out the same, .110.

Re: Optimum lifter preload [Re: A727Tflite] #2591442
12/13/18 06:49 PM
12/13/18 06:49 PM
Joined: Jan 2003
Posts: 14,478
So. Burlington, Vt.
F
fast68plymouth Offline
I Live Here
fast68plymouth  Offline
I Live Here
F

Joined: Jan 2003
Posts: 14,478
So. Burlington, Vt.
Originally Posted By Transman
A question for fast - in theory, wouldn’t weaker valve springs allow quicker and more violent lifter separation/pump up?

Wouldn’t weaker valve springs take longer to “pump down” the plunger versus a stronger spring?


I would think so.
In my case, the tired old 361 had the 100,000 mile stock single-without-damper springs...... so not much pressure.


68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads
Re: Optimum lifter preload [Re: fast68plymouth] #2591475
12/13/18 08:23 PM
12/13/18 08:23 PM
Joined: Mar 2011
Posts: 3,055
Michigan
A
A727Tflite Offline
master
A727Tflite  Offline
master
A

Joined: Mar 2011
Posts: 3,055
Michigan
Originally Posted By fast68plymouth
Originally Posted By Transman
A question for fast - in theory, wouldn’t weaker valve springs allow quicker and more violent lifter separation/pump up?

Wouldn’t weaker valve springs take longer to “pump down” the plunger versus a stronger spring?


I would think so.
In my case, the tired old 361 had the 100,000 mile stock single-without-damper springs...... so not much pressure.


So in my mind ( and you seem to agree a bit ) a weaker spring would take longer to pump the plunger down - and that may be why some engines like Ron’s buddy and your 361 too so long to regain compression.

Of course other factors may play in to this - condition of the lifter itself and maybe actual cranking oil pressure, would be a neat experiment.

Re: Optimum lifter preload [Re: fastmark] #2591521
12/13/18 10:07 PM
12/13/18 10:07 PM
Joined: Mar 2011
Posts: 3,055
Michigan
A
A727Tflite Offline
master
A727Tflite  Offline
master
A

Joined: Mar 2011
Posts: 3,055
Michigan
Thanks for all the replies to my questions -

Re: Optimum lifter preload [Re: fastmark] #2591606
12/14/18 01:10 AM
12/14/18 01:10 AM
Joined: Mar 2006
Posts: 9,791
MI, usa
dvw Offline
master
dvw  Offline
master

Joined: Mar 2006
Posts: 9,791
MI, usa
Pretty simple. If the spring pressure overcomes internal tappet leakage, it collapses the plunger in the tappet. Then the valve train loses lift. Valve train is noisy due to lash in the system until the lifter recovers and fills with oil. If the valve train loses contacts between components the lifter fills with oil trying to take up the extra clearance. Now the valve doesn't seat as the lifter is too long. Engine runs rough until the lifter bleeds the excess oil fill. Providing the the lifters don't leak down or pump up any preload will work.
Doug

Re: Optimum lifter preload [Re: fastmark] #2591830
12/14/18 02:05 PM
12/14/18 02:05 PM
Joined: Aug 2003
Posts: 1,310
Charlotte, NC
L
LSP Offline
pro stock
LSP  Offline
pro stock
L

Joined: Aug 2003
Posts: 1,310
Charlotte, NC
.010" worked best for my combo - SB with Morel Hyd. Roller lifter, PSI 1.290" dual spring 175 lbs. seat, 8300 RPM

Re: Optimum lifter preload [Re: fastmark] #2591883
12/14/18 03:31 PM
12/14/18 03:31 PM
Joined: Jan 2003
Posts: 6,363
Abilene, Texas
F
fastmark Offline OP
master
fastmark  Offline OP
master
F

Joined: Jan 2003
Posts: 6,363
Abilene, Texas
Well from what I am seeing here, it appears it does not really matter on a non performance application. As long as the lifter does not bottom out and go solid, it can’t hold open the valve, right? On a performance app, too much preload, robs you of lift. I guess it gets to a certain preload and stays at relatively the same position because it can’t bleed off
the oil pressure fast enough to matter. Am I thinking correctly here?

Re: Optimum lifter preload [Re: fastmark] #2591905
12/14/18 04:03 PM
12/14/18 04:03 PM
Joined: Aug 2003
Posts: 43,007
Bend,OR USA
C
Cab_Burge Offline
I Win
Cab_Burge  Offline
I Win
C

Joined: Aug 2003
Posts: 43,007
Bend,OR USA
Most stock lifters will pump up and hold the valves open at the upper RPM if they have to much preload, setting the preload from .010 to .030 hot will help stop that work


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Optimum lifter preload [Re: Cab_Burge] #2591934
12/14/18 05:05 PM
12/14/18 05:05 PM
Joined: Jan 2003
Posts: 6,363
Abilene, Texas
F
fastmark Offline OP
master
fastmark  Offline OP
master
F

Joined: Jan 2003
Posts: 6,363
Abilene, Texas
Originally Posted By Cab_Burge
Most stock lifters will pump up and hold the valves open at the upper RPM if they have to much preload, setting the preload from .010 to .030 hot will help stop that work


I keep going over this I’m my brain and I think this is has got to be the case. The higher the rpm, the more they will pump up. The more room they have to pump up, the more like they are to hold open the valves.

Re: Optimum lifter preload [Re: fastmark] #2591945
12/14/18 05:23 PM
12/14/18 05:23 PM
Joined: Jun 2008
Posts: 3,913
usa
L
lewtot184 Offline
master
lewtot184  Offline
master
L

Joined: Jun 2008
Posts: 3,913
usa
the valve spring controls pump-up, not pre-load. reducing pre-load just reduces pump-up distance.

Re: Optimum lifter preload [Re: lewtot184] #2592265
12/15/18 12:13 PM
12/15/18 12:13 PM
Joined: Jan 2003
Posts: 27,421
Balt. Md
3
383man Offline
Too Many Posts
383man  Offline
Too Many Posts
3

Joined: Jan 2003
Posts: 27,421
Balt. Md
Originally Posted By lewtot184
the valve spring controls pump-up, not pre-load. reducing pre-load just reduces pump-up distance.



Yes but the point here I believe is if you run the lifters with almost no preload even if you over rev the eng the lifters cant pump up enough to hold the valve off its seat. I have seen that a few times over the years on stock type engines. When I worked at a used car dealer I ran a 351 Mustang real hard on a road test and the lifters pumped up enough to hold the valves off the seats and stall the eng. I had to wait a bit before it got comp back. That's why I ran only about .010 preload in my old 383 since I raced it sometimes and used basically the stock valvetrain with Comp single springs. Course to close to no preload and it has more valve train noise. But I understand what you mean also about the spring tension making a difference if you run the normal preload. Ron

Re: Optimum lifter preload [Re: fastmark] #2592266
12/15/18 12:15 PM
12/15/18 12:15 PM
Joined: Jan 2003
Posts: 27,421
Balt. Md
3
383man Offline
Too Many Posts
383man  Offline
Too Many Posts
3

Joined: Jan 2003
Posts: 27,421
Balt. Md
Originally Posted By fastmark
Originally Posted By Cab_Burge
Most stock lifters will pump up and hold the valves open at the upper RPM if they have to much preload, setting the preload from .010 to .030 hot will help stop that work


I keep going over this I’m my brain and I think this is has got to be the case. The higher the rpm, the more they will pump up. The more room they have to pump up, the more like they are to hold open the valves.




Basically your right but the stronger valve springs will fight against the lifters pumping up and holding the valves off the seats. Ron

Re: Optimum lifter preload [Re: A727Tflite] #2592705
12/16/18 12:30 PM
12/16/18 12:30 PM
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
R
RapidRobert Offline
Circle Track
RapidRobert  Offline
Circle Track
R

Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
Originally Posted By Transman
Fastmark - how did you determine how much preload you have ? What method did you use ?
What I do is: with it mocked up, put a swath of dykem on the pushrod, then slide a thin flat razor blade over sideways from the valve cover flange on the head & make a slight mark in the ink then undo the rocker to let everything raise up till the cup "just" reaches the snap ring then make another razor mark then measure the distance between the (2) "marks" on the pushrod.


live every 24 hour block of time like it's your last day on earth
Re: Optimum lifter preload [Re: RapidRobert] #2592733
12/16/18 01:27 PM
12/16/18 01:27 PM
Joined: Jan 2003
Posts: 6,363
Abilene, Texas
F
fastmark Offline OP
master
fastmark  Offline OP
master
F

Joined: Jan 2003
Posts: 6,363
Abilene, Texas
Originally Posted By RapidRobert
Originally Posted By Transman
Fastmark - how did you determine how much preload you have ? What method did you use ?
What I do is: with it mocked up, put a swath of dykem on the pushrod, then slide a thin flat razor blade over sideways from the valve cover flange on the head & make a slight mark in the ink then undo the rocker to let everything raise up till the cup "just" reaches the snap ring then make another razor mark then measure the distance between the (2) "marks" on the pushrod.


I’ve done it this way before. I got the same measurements both ways. I fixed the problem yesterday without buying adjustable rockers at he customers request. I settled on .035 to .045 using Shim’s under the stands. It was a royal pain. Way too time consuming just to save the customer money and be a one time fix. I had to use more shims at one end of the drivers side head. Better than .110 to .145 preload though.

Re: Optimum lifter preload [Re: fastmark] #2592748
12/16/18 01:47 PM
12/16/18 01:47 PM
Joined: Dec 2004
Posts: 10,549
Rittman Ohio
fourgearsavoy Offline
I Live Here
fourgearsavoy  Offline
I Live Here

Joined: Dec 2004
Posts: 10,549
Rittman Ohio
I had to use more shims at one end of the drivers side head. Better than .110 to .145 preload though. work

That just doesn't sound like a good solution to me shruggy Wouldn't that stress the shaft? I wouldn't sign off on that repair twocents

Gus beer


64 Plymouth Savoy
493 Indy EZ's by Nick at Compu-Flow
5-Speed Richmond faceplate Liberty box
Dana 60
Re: Optimum lifter preload [Re: fastmark] #2592763
12/16/18 02:14 PM
12/16/18 02:14 PM
Joined: Jan 2003
Posts: 14,478
So. Burlington, Vt.
F
fast68plymouth Offline
I Live Here
fast68plymouth  Offline
I Live Here
F

Joined: Jan 2003
Posts: 14,478
So. Burlington, Vt.
Aaaaahhh yes........ the old “stand splitters”, er...... I mean shims.


68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads
Re: Optimum lifter preload [Re: fast68plymouth] #2592783
12/16/18 02:57 PM
12/16/18 02:57 PM
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
R
RapidRobert Offline
Circle Track
RapidRobert  Offline
Circle Track
R

Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
I dont have the last word on this but it recollected something about custom shims that someone offered that are thinner on the "sides" to counteract this.


live every 24 hour block of time like it's your last day on earth
Page 2 of 3 1 2 3






Powered by UBB.threads™ PHP Forum Software 7.7.1