Great video,very informative as always thanks for sharing your knowledge…

@powellmachineinc3179

9 ай бұрын

Glad you enjoyed it

Seeing is believing. Thanks for such a simple presentation of the facts! Hard to believe how this internet legend ever took root.

Thanks very much for this, and for sharing your knowledge in all of your videos.

@powellmachineinc3179

10 ай бұрын

My pleasure!

Great video. I’ve thought this for years as every lifter I’ve pulled out looks identical to an “LS7” lifter. But it’s great to have this video for reference now. 👍Truth is 90% of the time I don’t even replace the lifters unless they have a visual defect. I usually just inspect them, clean them out, recoil them, and shove them back in.

@powellmachineinc3179

10 ай бұрын

Right on

I know I can trust what Powel says! Much appreciated! Keep up the excellent work! When it comes to to build my 454 Hondo runner bottom boat engine I know who I’m calling!

@powellmachineinc3179

9 ай бұрын

Ty sir!

I just I love your KZread channel you are so informative it is awesome

@powellmachineinc3179

6 ай бұрын

Thank you so much!

Great video thanks for the info

@powellmachineinc3179

4 ай бұрын

You bet

Thanks for telling the truth and backing it up.

@powellmachineinc3179

10 ай бұрын

You bet

Rebuilding my FE 390 I bought a set of roller lifters from a known good company. The lifters on the bottom were very sharp You could basically shave with them. It removed material in the block shortly down the road causing too much clearance. So I called them sent them back they sent me a new set. I had the block rebushed and it's been running for years now no problem. The second set of roller lifters clearly had a slight bevel on the bottom of the roller lifter.

On my FE 390 build I told the company to not send me short skirt pistons. Well they did and they said said they will not make noise cold so I installed them. Well cold it had a horrible piston slap noise cold only. So they sent me another set long skirt installed those been running great for years no noise cold. Also on the same FE 390 the intake manifold didn't line up on the angle of the head so on de- acceleration manual transmission by the way it would suck the bottom of the intakes gaskets into the port. I do have that problem fixed as well communicating with NASCAR engine building guys.

Great info! The only things you didn't measure was plunger and check valve spring tension. That's the only other variable i can see with a lifter for a performance application. A stiffer check valve spring will resist pump up more. But that mystery will have to be dispelled as well...

@powellmachineinc3179

10 ай бұрын

Check valve tension is so light it's irrelevant, the "hydraulic " pressure is sealing the ball

I was constantly thinking this. I’ve watched a bunch of videos on ls lifters and how Jonsons tie bar,solid roller, and morel tie bars where an advantage over stock ls lifters. Them going through body designs and oil reliefs grooves and seriously couldn’t see a difference between the oem lifters when it’d be a ls3,ls2,ls7,etc. I know there’s been a huge “ls lifter failure” during peak Covid. I’ve been under the impression 95% of them are of failure to measure push rod length and account for preload. I understand the issue with flat tappet issues going on. Vintage iron covered it and I believe you also briefed over it. I’m more then likely staying with my oem lifters this go around on my ls3.

@powellmachineinc3179

4 ай бұрын

Glad it helped

Great video thank you👍😊

@powellmachineinc3179

10 ай бұрын

Glad you enjoyed it

It would be helpful to Rockwell test and compare the trunion, needles and roller wheels. That may shed some light on some mysterious lifter failures. Thanks for the great info.

@powellmachineinc3179

10 ай бұрын

I can do that

@TOMVUTHEPIMP

7 ай бұрын

These lifter failure are 95% builder error.

@biscuitpope3760

Ай бұрын

@@TOMVUTHEPIMPwould you please elaborate on what builders are doing to cause lifter failures?

@TOMVUTHEPIMP

Ай бұрын

@@biscuitpope3760 Backyard engine builders slapping stuff together with big cams, ignoring spring pressures, etc.

I pulled two sets of rollers from 90's chevy truck and yukon. I took them apart and cleaned them up. They look exactly like the "LS7" lifter. I did the David Vizard trick and shimmed them up internally to have only .030" travel. Then I adjusted off the bottom of the travel for .010-.015" based on thread pitch. He said he talked to the engineer who designed them and the designer never tested after 6-6500 rpm. They go flat rather than pump up. The plunger can rock enouph to bleed pressure.

@powellmachineinc3179

8 ай бұрын

2 thing's, #1 if they looked like the "2nd design they had been replaced, #2, if your lifter has a bleed rate that high you need a new lifter not shims, also they don't go flat after 6k thousands of dyno test/track passes debunk that.

@chrisreynolds6520

6 ай бұрын

​@@powellmachineinc3179 I think he may have gotten lifters out of a truck or trucks with Goodwrench L31 replacement engines from Mexico. I have owned a 2007 Mercruiser 5.7L, a 2003 Mexican built 5.7L L31 powered Sonora (GMT800 Tahoe rebadge) and a 2006 era Goodwrench L31 that I had in my 1997 Express. All 3 of the L31 engines built in the mid 2000s had LS style lifters as built from GM.

Thank you for your knowledge and video's USA 🇺🇸 USA 🇺🇸..

Ty for this. It was driving me insane. I have Delphi and I was debating on going to the dealership.........to get the same ass lifters. 😔

@powellmachineinc3179

7 ай бұрын

Yup

I have heard the guys from SDPC state, multiple times, that when the LS7 lifter was first produced there was an obvious difference and we can see that in the lifters you have. They stated that after about 18 months of use, the LS7 became the standard lifter at GM. After that point if you bough lifters at a dealer, you got LS7 lifters. It was the default lifter.

@powellmachineinc3179

9 ай бұрын

This "design " was available before the ls7 was available

@mrfarts5176

5 ай бұрын

I heard some engineers at gm say that someone just read the print upside-down, and for about 3 years, they machined these upside-down!

Thanks for the info concerning preload - trying to make it run as a solid lifter - I wont do that after hearing your explanation.

@powellmachineinc3179

9 ай бұрын

Glad to help

@1fast72nova

5 күн бұрын

​@@powellmachineinc3179 agreed I've tried to tell people for years the less preload the better.

It's all in the cup check just the cup depth. I have a set of the old ones too the cup is for sure lower.

@powellmachineinc3179

6 ай бұрын

Dang did you actually watch the video, ?

Nice info, i wish you had measured their outside diameter for lifter to bore ( my ST2126SLR for insane while their tolerance to each other is tight are slightly smaller to stock). Im not surprised they are made same or similar, i am surprised morel and others dont have different metals, axel diameters, wheel diameters, cup and disc tolerance and bleed sizes, nothing lol not even return spring heh damn... I didnt think there were different heights but i DID think metallurgy and bleed of rates were different even on standard travel drop ins ( Johnson SLR/ Morel ect)... Now i have personally seen a china copy fake "LS7" lifter and their wheel with on the roller surface was narrower.... I was told GM High performance aka Caddy lifters were different ( but didnt like over 380lbs over the nose and im about 420 with a heavy valve train comparitely, BR7 heads and turn it up with the high ram so went with the best ) Btw you doing GODS work lol, damn this is hilarious because ive heard LS7 lifters needs a 7.350 pushrod a LOT generically without actually measuring it on base circle of cam and THIS is where it comes from)..

Good video 👍🇦🇺

@powellmachineinc3179

10 ай бұрын

Glad you enjoyed it

Great information, so seems the marketing is the differences in prices as anything else. Summit racing has them Jegs, BTR, Michigan Motorsports, GM dealer no matter where you purchase getting the same product

@powellmachineinc3179

3 ай бұрын

Only gm unit's are made in the 🇺🇸

@ajsgarage3471

3 ай бұрын

@powellmachineinc3179 summit stated their lifters are produced in the USA as well but will not disclose the manufacturer so good chance it's a top quality lifter as GM

@powellmachineinc3179

3 ай бұрын

@@ajsgarage3471 then there just reboxed gm units

I’d like a set of LS8 lifters to go with my three-quarter cam please ;)

I am doing a swap on a 03' Crown Vic Police Interceptor Ls3/4L80. I was wondering about this and I was planning on getting normal Ls3 lifters.

@powellmachineinc3179

8 ай бұрын

Check our website Powellmachineinc.com

Plus from closed spring pressure on the valve seat a couple thou(.002)or so of back pressure at valve stem tip would be "put back into the positive of wear".

The only thing I have wondered is about metallurgy.

I've been watching a few of your videos, and it's nice to see people with common sense still. I thought .100 to .150" preload sounded ridiculous. I ordered shorter pushrods for an l92 build, to correct that. I've got them around .050" now. I've also played with a few small block and big block chevs, and I'm convinced that adjusting the preload tighter makes the cam act bigger. So if you send an ls out the door with .100" plus preload, the cam is going to act slightly bigger.

@powellmachineinc3179

2 ай бұрын

No amount of preload will affect the cam profile.

@shenaniganswhatsoever363

2 ай бұрын

@@powellmachineinc3179 not even a little? I would think the lifter is not perfectly sealed shut, and some amount of lift would be bled out. I might be wrong, but i'd swear the cam acts bigger the tighter the preload is. Probably take a dyno to prove it, so I'll leave it be. Seat dyno is deceiving lol.

@powellmachineinc3179

2 ай бұрын

@shenaniganswhatsoever363 in that way yes, it's bleeding, I'm saying more are less will not be different

@shenaniganswhatsoever363

2 ай бұрын

@@powellmachineinc3179 copy. thank you for the response.

Well, there goes the extra price markup on the "genuine, guaranteed, promise you, honest, proven, +25hp, 9000 RPM LS7 " lifters....

@powellmachineinc3179

10 ай бұрын

Lol, 💯

SUPER AWESOME tech, yea, no hyd roller/flat needs more than .030 preload, yes, always chk what manuf is recommending.......i just assembled a '62 409, with a hyd roller......Johnson wanted .030 preload........(3/4 of a turn) on a 7/16 fine thread stud.......030.....NOT .100!!!!....listen young bucks to what this man is sayin!!!.......after gettin correct pushrod length, and ordering the pushrods, i set it up Fri.......a true 409/409 from '62......dual quad, etc,.....4 sp car.......preload was accomolished at 3/4 turn (netting .030 to .032 preload)...THATS how its done!!!.....TY SIR for your smart vids, teyin to help out the less advantaged........PEACE to you sir!!

@powellmachineinc3179

10 ай бұрын

You are welcome, ty for the love!

@timothyarnott3584

10 ай бұрын

@@powellmachineinc3179 👍yea brother!!...

Ls lifters and small block Chevy roller lifters are interchangeable

@powellmachineinc3179

10 ай бұрын

I didn't say otherwise.

I should have said my block is a 1978 406 Sb

Great info. I’ve read all over the internet that LS7 lifter cups were .050 taller that the LS1 lifter. They are obviously taller but you proved the .050 number to be false.

@powellmachineinc3179

10 ай бұрын

The point is, there is no ls7 lifter , just a 1st and 2nd design

@bwill03z76

10 ай бұрын

@@powellmachineinc3179 yep. It’s kind of annoying that they call them ls7 lifters when it’s just a second gen LS lifter cause they are all the same

@milojanis4901

6 ай бұрын

​@@powellmachineinc3179 1st LS motor I ever built I ran '87-up SBC Eaton anti-pump ups. I ran them up to a 7,000rpm shift, no problems at all.

If you were building a 500-600 hp engine LS-XXX and wanted to STEP UP the lifter selection, What aftermarket lifter and design would you recommend? What rocker Pedestal would you recommend other than that stock aluminum POS?

@powellmachineinc3179

6 ай бұрын

Gaterman drop in, and oem rockers with our bronze trunion kit

According to internet bench racers and Brian Tooley, the “LS7” mojo is in a “stiffer spring and different check ball.” This is supposed to cause restricted oiling to the valve train at high RPM’s, to keep oil in the bottom end, and resist pump up and lifter collapse “valve float.” Hey… Don’t shoot the messenger! 😂

So i had a 7.350 pushrod, "ls7" lifter, milled heads, decked block, .660 BTR springs, .6xx lift cam. I had alot of clatter so i tore the engine back down and found alot of debris and garbage in the pan, lifters, ect. No bearing material tho, cleaned everything back up, remeasured preload and i have roughly. 055 to .065 preload. I havent fired it up yet. What are the odds my preload is fine and i clogged the lifters the first time around. I tore the lifters all the way down and soaked/cleaned the lifters as well as blowing the check valve out in the piston

@liljohn4777

4 ай бұрын

I also reliazed the little disc in my lifters are stamped with raised circles instead of the flat machined ones that show on all your lifters

I enjoyed the video. Unfortunately, too many builders seem to be squawking about lifter quality control issues. That all or most lifters are dimmensionally the same might not be the whole story.

@powellmachineinc3179

20 күн бұрын

Definitely, agree, we have less issues with our import lifters than many "high end" ones....

Question....can your use a LS roller lifter in a second gen block.?

I think a lot of this lore comes about from people really not understanding that the valve float they're experiencing is a valve spring issue, and not a lifter issue. Lifters basically don't compress once they fill with oil.

When I built my 02 ZO6 LS6, I went with Cadillac Racing lifters. (They were the HOT lifter of that time. The stock LS6 lifters that were removed from my LS6 were the early LS1 Designed exposed roller. I was impressed with the new Caddy lifter designed of the more shrouded roller. Is there a difference between the Caddy lifter and that second LS Designed lifter? Or Did I just get bamboozled like everyone else? They have held up very well and I have a fairly aggressive cam and run the engine pretty hard. Thank You for all that you do! Bill

@powellmachineinc3179

6 ай бұрын

All the same

@vinnyvette6028

5 ай бұрын

No they aren’t. The Caddy lifter is shorter travel and has a titanium check ball for weight reduction. Good for 8000 RPM. But you can’t use springs with more than 350 lbs open pressure.

@powellmachineinc3179

5 ай бұрын

@@vinnyvette6028 we've had many of them here, there the same as all the rest,

@powellmachineinc3179

5 ай бұрын

@vinnyvette6028 also weight reduction is a moot point behind the fulcrum and the ball is so small the difference would be unmeasurable

The original CTSV Cadillac LS7 race engine was said to rev to 8500-8700 with the original style LS7 Hydraulic roller lifter that had a ceramic check ball. That was According to the short little half page reading hot rod magazine years ago. So they may all be the same now. But what you get in the corvette street LS7 in the corvette is probably not what you get in the CTSV race LS7.

@powellmachineinc3179

4 ай бұрын

All "race" engines from gm were reported to have Johnson lifters, a ceramic check ball isn't really fixing anything, I have never seen one, would like to.

@DavidB7474

4 ай бұрын

@@powellmachineinc3179 just repeating what the little half page article said. The hydraulic roller lifters used ceramic check balls and they weight nothing. They said that was why they handle rpm so well. But thats been what 2007 so things change. I’ve spent way too long trying to find anything on that and looking for that article. One day I will come across that article and I will share it.

can you tell me if there is a problem with ls1 cam bearing spining in block thanks don

Next video Idea. Can or will it work? V6 roller lifters in 1st gen sbc . Without reduced base circle cam. Doing this right now on 383. Thanks . Haven't bought anything yet. Just heard about this. That they are shorter,oil feed hole lower. I have no inventory to check this out , my inventory is mostly sbf parts.

@powellmachineinc3179

10 ай бұрын

4.3 v6 lifters are tje same

@frankkoppen7281

10 ай бұрын

they were saying . 2.2 , 3.4 , 3.1 were shorter.

Basically what people call the ls7 lifter is the 4th generation lifter . The 4th generation lifter has the wheel captured. The internet says LS pushrods are 7.400 inches long. None of them have measured them 0.25 is my go to preload.

@powellmachineinc3179

10 ай бұрын

Early 2000's have the new design lifter, and stock pushrods are like 7392 ish, from the handful I checked

@davidreed6070

10 ай бұрын

@@powellmachineinc3179 I have got 385 but I guess they changed the lifters before the Gen 4 change

Thankyou you know they say it to sell it haha, they should just say not the ls1 lifter but ls7 sells better :) Any input on the delpi vs eaton debate, people saying the Eaton is flawed and Badley machined?

@powellmachineinc3179

2 ай бұрын

Delphi hasn't made a lifter in probably 10 + year's

So whats the deal with soaking lifters before install? I just received mine they actually got delivered in a bag already in oil. But I'm seeing videos of people saying don't soak it messes up the preload.

@powellmachineinc3179

3 ай бұрын

We like soaking so the bearings in the wheel have plenty of oil on startup

I've read the lifter bottoms out around .120 preload for LS designs. Using stock pushrods i have .098 preload measured with dial indicator (1.25 turns after zero lash) car runs but real bad, backfire and won't climb a hill. It's a new build. Do i have to much preload and require .050 shorter pushrods?

@powellmachineinc3179

4 ай бұрын

Most lifters have almost. 200 travel, .03-.060 is ideal but to much won't make it run bad unless you bottom out the plunger

Morel 5315 lifters? Morel states .120 of max travel and set preload at .050 for all aluminum engine. I have mine set at .060 and they become noisy (tick/clatter/sewing machine) only once engine is warmed up. Cold start absolutely quiet. Warm, noisy. Any input on what could possibly be going on? I run 15w50 oil due to .0025 mains and rods in an aluminum block. Melling high volume/stock pressure oil pump. Any insight would be much appreciated. Thanks

@powellmachineinc3179

3 ай бұрын

Preload will not make a lifter noisy (as longas you have some hot), only internal clearance or valving issue

@nickgarrett2533

3 ай бұрын

@@powellmachineinc3179 thank you for the quick reply. Yes, they only make noise when hot. When you say internal clearance or valving issue do you mean the plunger to body? Or lifter bore? I assuming you're saying the lifter is bleeding down to fast when oil is hot and thinner compared to cold start?

@nickgarrett2533

3 ай бұрын

@@powellmachineinc3179 these lifters would be the Morel 7717 you have on your website (5315 was old part number). Alot of forums stating they are noisy or certain oil weights are required (nonsense). Was just interested if you have heard any issues with the ones you sell. Thanks again

Once again, not arguing. Just asking 30000 says movement, less on the lifter means less oil too, right?

@powellmachineinc3179

Ай бұрын

Idk what ur asking and it's. 030" not 30000

In our shop, we grind additional lubrication groves into all ls7 lifters. We call them ls7 improved lifters. Their house lifter doesn't look like it has been hardened correctly. The ls7 spec includes additional hardness specifications and quality checks.

@foghornleghorn8536

3 ай бұрын

Not according to the people that make them.

Now I'm not arguing with you. I'm asking 30000 on a lifter different. What's that do with the Spring pressure? And the movement and opening the valves and everything 30000 it's amazing a lot. I mean, 16th is only 62 and a 1/2.

@powellmachineinc3179

Ай бұрын

Lifter preload has no effect on spring pressure

so if i can put a spider and dog bones in my 2 piece rms sbc . i could use your lifters on a roller cam ?

@powellmachineinc3179

6 ай бұрын

Yes

@stevenbelue5496

3 ай бұрын

I dont think so unless powell knows a trick im unaware of. The lifter bores are raised and decked on the gen 1.5 engines that have 1prms. Folks have tried with the older 2 piece blocks, running shorter 60° v6 lifters with subpar results.

You say all these lifters are identical as far as appearance and dimensions with machining. But what about hardest and material?

@powellmachineinc3179

Ай бұрын

Hardness is the same, can't speak on material, but if I was a betting man.....

I thought GM went to the LS7 style lifter for production of everything by 2008-2009, and also to replace earlier lifters.

@powellmachineinc3179

10 ай бұрын

If that's the case why do we have identical lifters in the early 2000's?

@v8packard

10 ай бұрын

@@powellmachineinc3179 I know you said that in the video. I have not compared those recently, but I did tear down a L31 Vortec that was a 2001 model this week. It has the early style lifter. I just checked. The lifter supplier told me GM used the LS7 style lifter in all production and as a replacement. It seemed correct based on replacement parts I was getting. And truth was, they were fine. I had zero problems with any genuine Delphi lifters. The same lifter being used to fill numerous part numbers is also not a surprise.

@chrisreynolds6520

6 ай бұрын

​@@v8packardI have had apart 3 L31s built post 2003 that had the newer lifter design. My 2003 Mexican Sonora, rebadged GMT800 Tahoe, my 2007 Mercruiser 5.7L and a 2006 era Hecho en Mexico Goodwrench L31. The L31 was used in trucks and SUVs until 2007 in Mexico and the Mexican built engines seem to all have the later lifters.

ihave lots ls1 2004 2005 engines from Holden 5.7 they had the updated lifters same as my 2006 6'0 engine theres one 2001 engine didnt open yet mybe ill find the older style

@powellmachineinc3179

5 ай бұрын

Yep

@jjjjjj9284

Ай бұрын

Great video mate 👍yep ive got about 150-200 of the earlier ls1 type lifters out of late 1999-2001 VT=VX/VU definitely thought there was a difference, Cheers for clearing it up

Hell, the 87UP GEN-1 SBC roller lifter is (IDENTICAL) specs and all to the LSX stuff! I wish you had one in that video, IDENTICAL!

@powellmachineinc3179

6 ай бұрын

There is one in the video, I even say it..

I've been in endless debates with people who will not except that lifters are the same, meaning dimensionally, not quality. The only real difference in them is quality of materials used to build them. The term "ls7 lifter" has always made me cringe when its listed in a build sheet as if that makes it special.

@powellmachineinc3179

9 ай бұрын

Yep, the interweb has ruined the performance world...

@hydrostaticshocker3048

9 ай бұрын

@@powellmachineinc3179 that it has sir

Whatever happened to the Johnson hydraulic roller lifter with the ceramic check ball that was introduced when the COPO & Cobra Jet factory drag rave cars returned years ago? Supposedly, they were good for another 300-400 rpm. It's amazing how much wrong information gets regurgitated around the internet and people have no critical thinking skills. I know you know and I understood what you meant but lifter pump would be that distance times rocker ratio so it could definitely get ugly quick with ridiculous preload and valve float

@powellmachineinc3179

7 ай бұрын

Those were "race" pieces, there not available any longer, put a check ball matl change is going to do squat to the rpm capability

The ls7 lifter subject and cam subject is the most irritating subjects. People ask what cam they should get, and 20 people will recommend the cam that they run without even knowing vehicle info. Or they recommend these performance companies. I have been brought cams from "x" performance company, and it has comp scratched out and their company initials scratched in. I always tell them to call a reputable cam company, and they will ask a lot of questions to get you the right cam. It drives me nuts.

@powellmachineinc3179

5 ай бұрын

Exactly,

They Say that the preload is different from LS7 to non LS7.

@powellmachineinc3179

6 ай бұрын

Well...we just proved there is no "ls7" so....

@gordocarbo

4 ай бұрын

@@powellmachineinc3179 Sometimes feels like youre talking to deaf people? Forum drones swear they will know more cause some guy with a bunch of posts says so . haha

You should get ahold of a 7.3 gasser lifter. Measure it out, compare it to those LS lifters. It’ll give you a giggle. Especially if you have the chance to work on a 7.3. I am a ford guy (I don’t know why either), but that engine has me shaking my head.

This accent is surreal

@powellmachineinc3179

5 ай бұрын

Thank you....I think 🤔

Hehe anyone that buys harber freight calipers cannot even read a ruler. I only buy premium snap on tool and i store them in genuine snap on tool boxes and i oil them with actual whale oil that is a century old. Very expensive oil.

David vizard has a completely different Opinion on the lifter preload in certain instances. I can find the statement if you like.

@jkdwayne

10 ай бұрын

David Vizard...... really over rated , and tells some shit that is totally wrong.

@powellmachineinc3179

10 ай бұрын

Na, I'm good

@jmc6940

10 ай бұрын

kzread.info/dash/bejne/ooCN3JaolbatcaQ.html 12:20

@alanmeyers3957

10 ай бұрын

Like no preload? If so, I agree.

So people are paying out the azz fir the LS7 name cause people think they are stronger. Lol. I was wondering about that.

@powellmachineinc3179

8 ай бұрын

Clearly there is 1 lifter from gm made in usa, so....

There is a difference if you buy the Chinese LS7 on eBay is junk and can ruin your cam and your engine! The Chinese LS7 the roller assembly softer metal and poor quality! The rollers pin placement is not precise some are crooked from side to side!

@powellmachineinc3179

Ай бұрын

Well...... we don't use ebay China lifters, and again ls7 lifters Don't exist

The .030 difference is strange, after normal cam break in and subsequent break in of other components from the cam to the valve seat there will be a change in dimensions/tolerances/geometry of the cam to valve seat operation, but definitely not close to .030 after engine is at normal running temp and all components "measure up" and all machine work and assembly are done properly.

Basically all the same hydraulic lifters, except the LS1, the only difference is a set can come in many different brands of boxes, are the vast majority of LS hydraulic lifters manufactured by the same factory machine shop? The .030 difference is strange, yes there's break in wear and later but if oil and coolant are maintained properly, definitely not even close to .030 from cam to valve seats, and valve seat wear would create a little back pressure on top of stem due to closed spring pressure maybe a couple thou.