lifter noise and pre load
TECH Fanatic
Joined: Jul 2007
Posts: 1,802
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From: Wilmington, De
I found in that one turn, 1/3 turn is for bolt preload and not actually applying preload due to rocker bottoming. By calculation I get 2/3 turn of the bolt to preload and 0.052" of lifter preload after correction for the rocker ratio. I also verified it with a dial indicator.
This is why I despise the bolt turn method for measuring preload and always tell people to just spend $60 on 8" calipers and be done with it.
TECH Regular
Joined: Dec 2011
Posts: 448
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From: SoCal
Originally Posted by MuhThugga
This is why I despise the bolt turn method for measuring preload and always tell people to just spend $60 on 8" calipers and be done with it.
I don't use the bolt turn method nor do I like it. I did a test on mine to figure out why the numbers being put forward were correct for one turn because the math didn't match. I check with turns, dial indicator and adjustable pushrod and got the same answer only when you account for bolt preload and rocker ratio when doing the turns.
Also, when using the caliper you are measuring OAL, not gauge length so that requires a correction as well.
Also, when using the caliper you are measuring OAL, not gauge length so that requires a correction as well.
If you are using the Comp Cam adjustable pushrod, the markings on it are NOT accurate (or should I say were not correct on mine). I measured it with a mic and it is close to .02" off in length at about the 7.375" length. Checked it 4 times. You would be adding an additional .02" of preload if you went by the markings, so 7.375" length would actually be 7.395". My factory pushrods all cam in around 7.395 - 7.400" range.
The thread pitch on the rocker hold down bolt is 1.25mm/rev. That calculates out to .049" per rev. No way to beat the math on that one.
The thread pitch on the rocker hold down bolt is 1.25mm/rev. That calculates out to .049" per rev. No way to beat the math on that one.
Joined: Aug 2007
Posts: 24,241
Likes: 89
From: Turnin' Wrenches Infractions: 005
If you are using the Comp Cam adjustable pushrod, the markings on it are NOT accurate (or should I say were not correct on mine). I measured it with a mic and it is close to .02" off in length at about the 7.375" length. Checked it 4 times. You would be adding an additional .02" of preload if you went by the markings, so 7.375" length would actually be 7.395". My factory pushrods all cam in around 7.395 - 7.400" range.
The thread pitch on the rocker hold down bolt is 1.25mm/rev. That calculates out to .049" per rev. No way to beat the math on that one.
The thread pitch on the rocker hold down bolt is 1.25mm/rev. That calculates out to .049" per rev. No way to beat the math on that one.
The factory pushrods are 7.385" gauge length. They are not 7.400" as stated over and over on the internet.
Second point you are half right. Yes .048" per rev, but you got the rocker geometry also. Your fulcrum is 1.7 away from the bolt, and the distance you are trying to gauge is 1.0 further away from the fulcrum vs the bolt. .048 X 2.7 / 1.7 = .076" preload per rocker bolt rotation. NOW you can't beat the maths
First point, you are correct.
Second point you are half right. Yes .048" per rev, but you got the rocker geometry also. Your fulcrum is 1.7 away from the bolt, and the distance you are trying to gauge is 1.0 further away from the fulcrum vs the bolt. .048 X 2.7 / 1.7 = .076" preload per rocker bolt rotation. NOW you can't beat the maths
Second point you are half right. Yes .048" per rev, but you got the rocker geometry also. Your fulcrum is 1.7 away from the bolt, and the distance you are trying to gauge is 1.0 further away from the fulcrum vs the bolt. .048 X 2.7 / 1.7 = .076" preload per rocker bolt rotation. NOW you can't beat the maths
If I understand you, you are stating .049" (1 rotation of the bolt)equals .076" of preload. I am not getting that number. I messed with it Sunday for a while also and didn't come up with the calculations using the adjustable pushrod checker either. I am probably off, but it isn't coming out that far.
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Verdad Gallardo Gotcha. Part of that is the rotation to torque the bolt. When you torque the bolt you are actually stretching the bolt and no longer applying preload.
When using bolt rotation, you stop when the wrench just stops with very little force.
When using bolt rotation, you stop when the wrench just stops with very little force.
Joined: Aug 2007
Posts: 24,241
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From: Turnin' Wrenches Infractions: 005
Hmmm...if I understand what you are saying, that isn't what I came up with when I physically measured it just a few minutes ago. I did it about 10 times to make sure I had the free play correct. I torqued the bolt to 22 lbs and counted just a bit over 1.5 turns from when the tip of the rocker lost its freeplay on the valve stem. That should be about .075" to .08". I took an indicator to the pushrod side of the rocker right above the pushrod and measured the distance traveled. I came up with about .087" of travel.
If I understand you, you are stating .049" (1 rotation of the bolt)equals .076" of preload. I am not getting that number. I messed with it Sunday for a while also and didn't come up with the calculations using the adjustable pushrod checker either. I am probably off, but it isn't coming out that far.
If I understand you, you are stating .049" (1 rotation of the bolt)equals .076" of preload. I am not getting that number. I messed with it Sunday for a while also and didn't come up with the calculations using the adjustable pushrod checker either. I am probably off, but it isn't coming out that far.
All this bs is why I will be going with solids one day soon. Any chevy I ever built always had flat tappet solids. When I put my morels in I did not realize that they are .050 taller than stock. The car started and ran but with a continuous popping lean sound. I checked compression and got 0 on some cylinders and compression would creep up going from back to front, 0 to 235psi. I then researched and found the .050 reason. Scratched my head and then panicked. Things like crushed valve seals and possibly bent valves ran through my mind. Especially because I gave it a test in wide open mode and it flew right to 7100 rpms of a stop sign. Then I thought I must be right at the edge of the valves sealing. Some hanging open some closed. So I backed them all off .005 and got full compression in all cylinders and now I know exactly how straight and square my block is. less than .005 from corner to corner! Not bad but pushing the lift to over .670. Yikes! Went from 7.4 to 7.375 pr's. It ran ok but went right to 7.350 calming the cam down quit a bit. To much maybe? I guess the track will tell me.
Just thought I would share my experience of going backwards. lol
Just thought I would share my experience of going backwards. lol
All this bs is why I will be going with solids one day soon. Any chevy I ever built always had flat tappet solids. When I put my morels in I did not realize that they are .050 taller than stock. The car started and ran but with a continuous popping lean sound. I checked compression and got 0 on some cylinders and compression would creep up going from back to front, 0 to 235psi. I then researched and found the .050 reason. Scratched my head and then panicked. Things like crushed valve seals and possibly bent valves ran through my mind. Especially because I gave it a test in wide open mode and it flew right to 7100 rpms of a stop sign. Then I thought I must be right at the edge of the valves sealing. Some hanging open some closed. So I backed them all off .005 and got full compression in all cylinders and now I know exactly how straight and square my block is. less than .005 from corner to corner! Not bad but pushing the lift to over .670. Yikes! Went from 7.4 to 7.375 pr's. It ran ok but went right to 7.350 calming the cam down quit a bit. To much maybe? I guess the track will tell me.
Just thought I would share my experience of going backwards. lol
Just thought I would share my experience of going backwards. lol
I got the amount of 80 preload per one bolt turn. I did not measure when part of the turn was the bolt being torqued. I selected one full turn but with the bolt far enough out that the one turn didnt cause it to snug. I got approx 80 at the pushrod with one free spin of the bolt.
Quote:
Originally Posted by lastlumina
Brian, dose the Morel 5315 lifter and pushrods 7.400 works together with no issues while used cam is BTA IV?
The Morel 5315 lifters are right at .025" shorter than stock or LS7 lifters, however 7.400" pushrods should still yield around .050" preload which should be sufficient. Right from Brian Tooleyhttps://ls1tech.com/forums/generation-iii-internal-engine/1737013-cam-recommended-2.html#post18331701 thread #25
Teching In
Joined: Dec 2007
Posts: 27
Likes: 0
From: Plainfield, IL
I'm not sure, but when I measured my morel 5315's against stock they were about 0.02" shorter. I ended up using 7.325" pushrods in my on a comp core with LSL lobes. This is also with a 0.040" head gasket, and the heads milled 0.035". I used my adjustable pushrod to get to zero lash, measured it with a caliper, and then added to get my desired preload. I used dial indicators to ensure I was reading true zero lash and I also measure 4 random cylinders intake and exhaust. My opinion is to run a lower preload to prevent valve loft from lifter pump up (low intake P/V clearance). So, I shot for around 0.020" preload. I always ran about a 1/4 turn past zero on my hydraulic SBC motors and had the most success there and they weren't noisy. Maybe you guys will argue about possible power loss, blah, blah. But I think a hydraulic is a hydraulic and all of them make less power than a solid roller. Two, if your valvetrain is unstable your going to make less power anyways and I would rather be safe know my valves can't hit pistons. Three there no way it will make less power than more preload unless two happens, or the lifter collapses.
I'm running a 5206 morel racing lifter w/link bars and .750 roller. Yellow bullet sponsors say they can run these Hydraulics to 8500 rpm with a solid cam and 250 seat pressures due to its new valving using less oil in the travel slot(.141 travel) and super close tolerances for greater stability at high rpm. These are for running in hydraulic classes having as close as possible of an effect as a solid lifter(no collapsing). So I guess your calipers are fairly accurate with what you have. 