Demystifying Lifter preload and Pushrod length

We go over how to set lifter preload and determine the proper pushrod length .
Powellmachineinc.com

[@PCMenten]

Limiting the amount that the lifter can pump up was my takeaway from today’s video. Thank you, sir.

[@powellmachineinc]

Exactly

[@jcnpresser]

Yes very useful information. Getting ready to swap a set of heads in my sbf ho motor. Video couldn’t have come at a better time. Now I need a video on pistons to valve clearance and what’s the best way for a back yard machinist to clearance the piston if need be.

[@powellmachineinc]

@@jcnpresser kzbin.info/www/bejne/sIOnfGtthLZsgdk

[@jcnpresser]

@@powellmachineinc thanks just got done watching. Was wondering if you’ve put heads with a 2.02 valve on a stock bottom end ho motor and if it’s true that you have to open the piston pocket up? For the intake valve? From what I’ve come across is that there’s not enough room, radial ways. And that’s what you’ve got to grind or fly cut the piston for.

[@jeffreydurham5342]

@@jcnpresser it's not difficult to check piston to valve clearance.

[@ZWortek]

I know nothing about V8s other than the basics of LS motors and what I've learned in these videos, but I just like watching and learning from someone who knows what they're talking about 😆. Plenty of information translates to other engines, too, which helps understand how something like engine block machining works and what's affected.

[@powellmachineinc]

Glad it helps! That's our goal

[@douglasbuckland8280]

I learn something new on almost all of these videos. Thanks for taking the time to make them.

[@powellmachineinc]

Absolutely 💯

[@joefrasson8997]

Nice to see an honest machinist...

[@powellmachineinc]

I try

[@ronsel4704]

Always made sense to me to do it just like you show. 8" Calipers are less than $30. Set up to 0 lash, measure the length, add your desired preload, order the closest length pushrod. I read all the BS about counting turns of the rocker bolt, etc etc, and my head was spinning. I told them how I did it, just like you do it, and just got arguments. Coming from the solid roller BB chev world, LS is dirt simple.

[@powellmachineinc]

Yep

[@ShawnGilbert1967]

Thread pitch of rockers studs can be measured and used as a tool, just exactly like HE said his pushrod length checker works by counting twist to Seay literally. However who would do that over an 8" caliper lol, I would use it as a check going together ( turns from 0 lash to Seat of bolt) just as a reference for future....this is the best way... I absolutely disagree on LS being easier, it's a non adjustable valve train..THIS part is all you get to do....ive run solid rollers on BBC on street with dissimilar metal bushings on down...ive run billet core hyd roller lobes with a solid roller lifter and spring pressure right in the middle boosted with a F1A-94 procharger that lived on the street forever but had to be precisely lashed cold... These ST2126SLR Johnson short travel lifters in my darton sleeved gen 4 block ( ls7 heads ) were the absolute most nightmare ever to get THEIR suggested .035 preload plus or minus .005, OH MY GOD 9 different lengths, which had to be custom ordered because as he mentioned most sell in increments of .025....lol.... It's just funny to read I'm like God I wish I could just lash these cold and check hot like my BBC's, once setup hopefully it's one and done but damn it wasn't easier ( .662 lift cam too)

[@StuartBlake-iz6rf]

Great job sir. Your common sense approach, excellent explanation and perfect visuals leave no grey areas. Thank you for your channel.

[@powellmachineinc]

You are very welcome

[@rtrayl]

Thanks for explaining that, there is so much out there that is just confusion.

[@powellmachineinc]

You bet! It's like white noise...

[@troysmith9471]

Been watching your vids for some time now and are greatly impressed with your knowledge. I was all set to buy 3 used ls3 and bring them to you and have them machined and assembled the right way and not have a bit of concern.(since I'm only 20 miles away from y'all) now it'll be hard finding a machinest of your caliber. Thank you

[@powellmachineinc]

We are booked till the end of the year, check with me end of summer and we will see what the schedule looks like

[@ShawnGilbert1967]

Thanks for the Video, hope you keep doing them!!!

[@powellmachineinc]

That's the plan!

[@adaycj]

Nice video! I was asked to advise someone on lifter preload recently. After my advice, we talked about the advice given from others about lifter preload. There is just some exotic imaginary things happening in people's heads sometimes. 😮 Thanks for the concise video on the topic!

[@deankay4434]

This was great info worth watching twice! The 5.3L iron block truck engine I have, had stem tip wear visible on every valve or drivers side. I can only figure the PCV pulled carbon & other contaminants to cause wear. I bought an extra rocker cover from the salvage yard, rotated the PCV pipe backwards then placed my 3/4” copper pipe down the center to draw of crankcase vapors. It made sense to go into the center to remove gasses and run clean air into left and right for longevity without this wear. Maybe off topic a little but I think why, then answer problem and act. The center pipe is drilled to drain liquids as it’s stuffed with SS wool. I used blind rivets into the thin valley pan and thread it out the front. This engine had 100k because it a family member I serviced. It was normal driven, not a hot rodded. Visible wear to me is too much, too soon!

[@powellmachineinc]

Definitely

[@jmc6940]

7.325 was the length pushrods i used for an lq4. Heads and block decked lightly with mild RV cam. 200,000 on engine and going strong. Daily driver.

[@thekingscene]

Thanks for sharing some actual truth on this subject. Getting close to that 25k giveaway!! Haha. Keep up the good work man

[@powellmachineinc]

100%

[@lazyhoundracing9621]

Thank you for explaining that and thank you for your time.

[@powellmachineinc]

Glad it was helpful!

[@josecarreira8934]

Another great vid on fixed rocker pre load and pushrod length.

[@powellmachineinc]

Thanks 👍

[@hornet340]

Might be worth mentioning to allow for the block & cyl head growth on all aluminium engines - this can decrease the preload by close to .020” at full operating temperature.

[@powellmachineinc]

So ,this is exactly why we preload in the first place also a all aluminum Ls will only grow about. 010"

[@catfissh]

@@powellmachineincsorry to butt in here but for my HC ls1 I measured 11 to 0 preload, I got Johnson 2110 lifters which require .035 preload +-.010, would you recommend I use .045 preload for the aluminum expansion?

[@bdugle1]

This info makes a lot of sense. It’s very different from what BTR told me. I have about 0.620 intake lift vs the original 0.460 or whatever. My heads are milled 0.018, stock deck height, and 0.040” gaskets vs stock 0.051”. The base circle should be 0.090” smaller radius, but the valve job, milling and gasket differences eat probably 0.035-0.040” of that. Their insistence on 7.425” pushrods is probably longer than I need. The BTR springs are pretty heavy, so I’m unlikely to float the valves below 7000 rpm. I wish I’d seen this earlier though! Thanks for another dose of great advice!

[@The340king]

I had to run zero lash with my hydraulic cams in circle track or I would get a high rpm skip. By high rpm, I was running over 7,000 rpm in a 2 bbl limited modified class. I turned 7,400 at BHS and 7,200 at SD SFS.

[@KidCoyle]

Thanks for all the info.

[@powellmachineinc]

You bet!

[@jim8027]

Great video. Having never done any of this, I had no idea it was actually fairly involved. The explanation was crystal clear.

[@powellmachineinc]

Glad you enjoyed it!

[@BEANS-O-MATICtransmissions]

@powellmachine the internet says.... There's varying heights on the LS cast rocker stand and to always use billet. Have you seen much height variance in the OE stand?

[@powellmachineinc]

No, there pretty consistent

[@hotrodray6802]

🔔😎🇺🇲 OK, I read down in these comments where you said that this does NOT apply to adjustable rocker arms. I missed your saying that in the video. Can you do a video on adjustable arm geometry... Ill look over your older videos to see. Thanks for your great teaching sessions.👍👍

[@powellmachineinc]

I have one coming

[@ChristopherWall-xh2xm]

Outstanding explanation ! Thanks for the insight 👏

[@powellmachineinc]

My pleasure!

[@mikef-gi2dg]

I haven't done an LS yet, but this is valuable info for the future. I notive you are working on an AFM block. What is the real scoop on AFM block valve train problems?

[@powellmachineinc]

This block is not afm, it wasn't available on this engine.

[@strokermaverick]

Thank you, for another insightful video!

[@powellmachineinc]

My pleasure!

[@strokermaverick]

@@powellmachineinc Daniel, if I had your brain, I'd throw mine in the trash!😃

[@mikeleschber33]

Another great video! I have always set the preload as small as possible and have never had an issue. Thanks for sharing your knowledge with us!

[@powellmachineinc]

Right on

[@Stormin06096]

Great information.

[@powellmachineinc]

Glad it was helpful!

[@michaelphelps5064]

The Ford story explains why there is so much available preload travel on hydraulic lifters. It's there to take up those tolerance stack ups and machining diffefences.

[@powellmachineinc]

Definitely

[@rickyfulks889]

Appreciate ya sharing good info coming from a pro

[@powellmachineinc]

Glad to help

[@enginemechanic-fo8ie]

I see my name on the white board behind you 😅 . How do you setup your sbc roller tip rockers on the valve tip i have see a couple different ways to set them thanks

[@powellmachineinc]

That video is coming

[@dirtydeedzmainecultavator68]

great information on the vidoes👊

[@powellmachineinc]

Glad you like them!

[@blairlardy]

you helped me out thanks for the informative video with no bullshit

[@powellmachineinc]

100%

[@henrybobswillikers]

Great info man thanks.

[@powellmachineinc]

You bet

[@AraCarrano]

Would have left it, the typo was eyecatching. Thank you for sharing your wisdom.

[@powellmachineinc]

Lol, well...

[@freeidaho-videos]

Thank you! Nicely explained.

[@powellmachineinc]

You're welcome!

[@llamattude]

one man man machine shop Been measuring for years try to run 0 lash on all hydralic lifters for years with no issues cams don't ware out with the right springs no valve issues

[@powellmachineinc]

You will actually have lash when it gets up to temp, that's the purpose of preload.

[@jmits1779]

i mate im just doing my pushrods and they were all just over 1/2 a turn but one of them was in the middle of 1/4 and 1/2 turn, with pushrod checker its telling me its got max around 30thou pre load, does this seem correct at that amount of turns? Should i get 25 thou longer pushrod for that one that will bring that to 3/4 turn?

[@michaeloboyle8798]

Makes perfect sense. Thanks for the video.

[@powellmachineinc]

Glad it was helpful!

[@musclecity06]

Im happy to see someone who actually uses a pushrod tool instead of that turns crap..the method you use takes no time and can result in a more accurate reading..its also more accurate when you get into the reduced travel lifters like johnson

[@powellmachineinc]

Absolutely

[@fasst5511]

That is all measured with everything cold. How do those measurement's change when the block and heads are hot and grow and what about cast iron block vs aluminum block?

[@powellmachineinc]

That is the reason we need preload, preload is reduced at temp

[@fasst5511]

Was curious if you knew how much it was reduced and should you bake that into the cold measurements.

[@powellmachineinc]

@@fasst5511 roughly. 010 on a aluminum engine

[@avp5964]

Hydraulic roller SBF with roller rockers. I was always told to spin the pushrod while tightening the rocker, as soon as there's resistance tighten 2 full turns. What's best? Lifters are shimmed for limited travel, more like solids if that matters.

[@powellmachineinc]

2 full turns is insanity, 1/2 a turn is std procedure

[@avp5964]

@@powellmachineinc Thank you so much!

[@reevesautomotivefarm9614]

Fantastic video. I recently found out how push rod link works on shift rockers on my small block Chevy. Wish I had seen this video first with a save me a lot of time.

[@powellmachineinc]

Glad it helped

[@6xcchamber971]

I should have watched to the end. On my 5.3 I found zero lash with the standard 7.4" pushrod. Will I need to get a longer pushrod about .075" Longer?? Thank you for taking the time to show how its done!

[@powellmachineinc]

@@6xcchamber971 the chances of needing a pushrod longer than 7.4 is pretty much zero

[@6xcchamber971]

@@powellmachineinc Thank you!

[@kennethward3354]

Thank you

[@powellmachineinc]

You're welcome

[@geniemattson1578]

great videos, please correct me if I’m wrong. As you lengthen or shorten a push rod the angle of the push rod changes per engine configurations. The change the angle can add or subtract lift. At the same time your valve tip pattern would change, but if you need a small edge when you’re racing. Is it worth it? Would like to see you so bad for a small block Chevy thanks.

[@ronaldmattson8373]

Sorry, on my last sentence I meant to say show that if you could on a small block Chevy.

[@powellmachineinc]

kzbin.info/www/bejne/qaHPqX6ogMSHiKs

[@ronaldmattson8373]

Thanks for the reply, and the great video. I was talking about the angle of the push push rods When you lengthen them, you can actually get more valve lift. You may not be anywhere close to center of the valve tip, but you will get more valve lift and thanks again for your replies.

[@kevinwest3689]

Let's say you have 0.100 piston to valve clearance. And your spring preload is say? 0.075 would this keep it from hitting if float lifter?

[@powellmachineinc]

@@kevinwest3689 should be fine

[@jeffreydurham5342]

Not to take away from anything you mentioned, but it's actually worse when you figure rocker ratio. 0.100 preload would become 0.170 or so at the valve if the lifter extended in a float situation. Thanks for sharing your knowledge!

[@jeffreydurham5342]

In a ls your 0.600 lift cam suddenly becomes a 0.770 lift cam!

[@powellmachineinc]

Absolutely correct

[@GrandPitoVic]

Good video brother!!! You said to 600 lift and 625 to 635 lift. I am running a .617 intake and .619 exhaust. Does that mean I am in-between the 7.375 and the 7.400 pushrods? I was sent 7.400s with my kit I bought for my swap almost a year ago. Thank you for the content brother. You can never know everything, so you making videos I pick up a little more each time.

[@powellmachineinc]

That is correct, 7.4 should be fine

[@GrandPitoVic]

Woohoo, thank you sir!!!

[@roadracer663]

I don’t understand why the lift could have influence on the lifter preload? The zero lash is measured ont the base circle, and the lifter preload is also there to compensate Valve tip clearance when lifter rolls on base circle. So why are we talking about lift? Could you explain please?

[@MarineGrunt]

This episode takes me back to another video you did . It was titled ' Customer accused me of not doing a valve job ' . Incorrect push rod length , excessive pre-load , would have produced similar results ...correct ?

[@powellmachineinc]

Yes sir

[@rickkelsch2040]

If you don't use enough preload with a high lift, higher load spring, it will resault in a loud valvetrain with factory travel lifters. The best thing to do is get a short travel lifters which will resault in minimal space under the lifter plunger and give enough preload for expansion. The spacer is not a bad idea too.

[@powellmachineinc]

Lift is irrelevant, lifter function doesn't change from cam lift

[@thisisyourcaptainspeaking2259]

I shoot for 0.020" lifter preload in sbc (sbc flat tappet has always been my bag up to today).

[@powellmachineinc]

All iron I 💯 agree

[@sidequest.517]

What are the right questions to be asking your machinist to make sure you don't end up in a situation like you mentioned with the FE ford? Is it as simple as asking if they verify valve tip heights, or is there a smarter question to be asking?

[@powellmachineinc]

Absolutely, if they don't have a stem hieght gauge....find another shop!

[@christophercullen1236]

I am not Familiar with LS engines at all , what are the 8 pillars in the valley for? Kit from down under

[@funfun8095]

Those have oil passages in them and are opened up in DOD engines, to control the oil to the DOD lifters. This wasn't/isn't a DOD engine, so you see they look solid.

[@christophercullen1236]

@@funfun8095 instant for cutting fuel on low load to save fuel , I looked up DOD from your reply?

[@powellmachineinc]

Dod system

[@juliodiaz8280]

Question Does it make a difference if you soak the lifters in oil for x amount of time compared to just coat lifter of oil and install?

[@powellmachineinc]

It doesn't effect pushrod length

[@juliodiaz8280]

@@powellmachineinc thank you.

[@HeadFlowInc]

Question: If limiting the area the lifter pumps up is the goal; what difference does it make if the “travel” is at the top/bottom of the plunger travel? Running “Deep” preload is a cheap way of creating a limited travel lifter. Yes limited travel lifters are less forgiving. BTR recommends more preload for better control with higher spring pressure and rpm. Old school builders use to run 1/4 turn or less lifter preload to try and get every bit of lift available with the lifter pumped up.

[@powellmachineinc]

Watch the video again, I answer the question clearly

[@mikeoakes7721]

Thanks for the video!

[@powellmachineinc]

You're welcome!

[@UlyseKnight]

I'm looking for a cam and lifters for a 5.7 hemi. can you help me out? It does not have that system that shuts the pistons down 2 4 cylinder does not have that system never did.

[@powellmachineinc]

Yes

[@russcole5685]

Are there adjustable rockets available, so you xan adjust lush on each without the need to buy separate size pushrids to suit

[@powellmachineinc]

@russcole5685 why would u need separate lengths un a hydraulic system??

[@russcole5685]

@powellmachineinc well, watching the video, with a rebuild, they're saying you need to measure what is needed over using the originals. I'm asking if there is a adjustable rocker available, so you can set the correct lash needed in one order and assembly.

[@davidbright1489]

Thoughts on the old way of marking the tip of the valve with a marker, installing everything then rotating a few times. Where it wears thru the marker should be centered on valve stem…. Was told too far towards the valley it’s got too much push rod and opposite if west is toward the outside of the head. Would that be a geometry thing instead?

[@powellmachineinc]

Again, this is a fixed rocker system, that doesn't apply to non adjustable valve trains.

[@davidbright1489]

@@powellmachineinc gotcha just making 100% sure because you got dudes out there still saying it. Now go do a video on non fixed lol, I can see on non fixed there being options and some are better than others?. Been binge watching your videos and man Iv learned a ton (20+yr mechanic) and it makes wanna work in a machine shop. Keep up the good work and videos!

[@nickgarrett2533]

You can shim the rocker stand but not really an issue till you start getting into some high lift over .600. At that point an aftermarket adjustable setup would be ideal

[@earlbrown]

That's an old wives tale that just refuses to die. And the exact wrong way to find out pushrod length. If the contact patch is wrong on an adjustable height valvetrain, you have the wrong rockers. And the solution for the wrong rockers isn't pushrods that are way too short.

[@powellmachineinc]

@@davidbright1489 will do, I have some coming down the line

[@juniorsnowbird]

No one seems to talk about the torque spec on the rocker bolt. What if you torque the rocker bolt to zero lash then add .030-.060 to the length of the pushrod for preload.

[@powellmachineinc]

9nce the rocker is seated you could torque it till the thread's pulled out and it can't change the preload because the rocker can't move any more.

[@juniorsnowbird]

@@powellmachineinccorrect but I’m talking about torquing the bolt at zero lash, no more, then add length to the pushrod to obtain proper preload

[@billsmopars4927]

Should you check with the heads bolted down?

[@powellmachineinc]

I'm confused? The head is bolted down.

[@douglash3129]

Hi Daniel, thanks for the information! Now this video only pertains to (non) adjustable rocker arms?

[@powellmachineinc]

The preload of a hydraulic lifter is across the board, but in a stud mounted system it's 2 fold, preload plus geometry

[@douglash3129]

@@powellmachineinc Yes, I just wanted to clarify Positive stop or adjustable on the push rod length deal!Thanks Daniel!

[@hotrodray6802]

​@@powellmachineinc That's what confuses me vs this pushrod length method. Geometry.. the sweep of the contact patch on the valve stem.

[@powellmachineinc]

​@hotrodray6802 I'm going to do a video on a adjustable rocker system

[@engineheader]

did you do this with dry lifters or ones soaked in oil? or does it not matter?

[@powellmachineinc]

It's irrelevant

[@jeffclark5024]

Please correct me if I’m wrong but isn’t the base circle of a lot of aftermarket cams smaller? Which would actually require a slightly longer pushrod? I tossed a BTR cam kit in my 02 Tahoe, came with the 7.4’s but it’s just a little on the noisy side. Was originally told this would be fine but now I’m second guessing it and I just ordered an adjustable push rod. (Something I should have checked from the get go)

[@powellmachineinc]

The base circle decreases with lift, the factory cam uses a pushrod about. 100" to long to start with

[@jeffclark5024]

@@powellmachineinc any thoughts on why they run so much lifter preload from the factory? To compensate for valve train wear? I mean I’ve taken these engines apart that have all the hardened surface worn off the pushrod ends and the rocker arms and they’re still quiet as can be.

[@Simple_Youtube]

I have a Gen 4 LS2 with a BTR stage 2 cam kit and LS9 head gaskets. Im running .080 preload. BTR says 0.100. I measured a 7.5 pushrod. When i use the 7.4 pushrods from the kit, my valvetrain is mush much louder than it is with the 7.5 pushrods. Thoughts? Stock 243 heads with BTR dual valve springs amd Ti retainers.

[@powellmachineinc]

Once you achieve preload adding more won't make more or less "noise" , noise is the absence of preload or internal issues with the lifter.

[@anthonypritchard7710]

Same process apply to a factory roller cam small block?

[@powellmachineinc]

No because the rocker can change its fulcrum hieght

[@chopper1168]

I know this is your job and business. Do you have a video on how you learned your trade. Fascinating to me

[@powellmachineinc]

A origin story video is coming

[@chopper1168]

@@powellmachineinc cool thank you sir

[@ccooper04]

I was measuring mine this past Friday and I’m running a decked block with prc 260cc heads. Intake came out to 7.50 and exhaust came out to 7.338 I was checking by turning the crank until I felt the exhaust start to leave base circle to get intake entering its base circle. Vise versa. If there’s another way to verify base circle or where to check let me know.

[@powellmachineinc]

@ccooper04 there no way the int and exh is a .160" different

[@ccooper04]

@@powellmachineinc I’m going check them again this Friday when I get off work. I may call to verify I’m doing everything right when I go to check them again.

[@ccooper04]

@@powellmachineinc I rechecked everything and pushrod length came out to 7.504 on both intake and exhaust. I figured out what I was doing wrong too.

[@mikebeale9242]

Since you do not sell long block engines yet..is there anyone you could recommend purchasing one from 05 5.3 vin T …I live in Va. thanks !!

[@powellmachineinc]

We sell them, I have on close to being ready, we are just EXTREMELY busy

[@mikebeale9242]

@@powellmachineinc .. I would be interested in purchasing one from you.. if you have one ready in the near future.. I know you are busy..so just let me know if you will be interested or not…and what I need to do..thanks !!

[@alanmize5627]

liked it

[@powellmachineinc]

Ty!

[@largesfc]

I assume the cam is on the base circle?

[@powellmachineinc]

It better be

[@largesfc]

I just didn't catch you saying it. Just wanted to make sure I didn't mess it up.

[@kellybrown1860]

Good Stuff thank you

[@catfissh]

Just tried this on my ls1, I got 11 turns out on my pushrod checker for zero lash. Did the math for .045 preload and got 7.395, I’m using Johnson 2110r lifters do you think if I use .050 preload so I can order 7.4 pushrods, you think it would be safe on that lifter? My setup is a stock bottom end ls1, torquer v4 cam and tsp ls6 brawler heads

[@powellmachineinc]

That should be fine

[@rickyfulks889]

Im by no means an engine builder but i get ur oount. I always out very lil preload on lifters, 1/4 turn mayb. Which is about. 015

[@powellmachineinc]

That's to light on a all aluminum engine

[@matthewsimons7146]

So an all aluminum LS engine with morel 7717 lifters takes .060 preload +/- .010 , is that one turn and a 1/8turn if one turn ? On a not adjustable oem ls rocker ONE TURN is .050 right?​@powellmachineinc3179

[@SixBarrel]

Thanks for your Time , all this information Is very useful , for any that want to build o keep rolling a High performance engine 🍻 .

[@powellmachineinc]

Glad it was helpful!

[@86boostdcapri]

Makes me want to swap out my 7.425 pushrods for my 7.400s now. I have ls7 lifters and everything I was seeing said to shoot for .100 preload so the 7.425s got me between .090-.095.

[@powellmachineinc]

No such thing as a "ls7" lifter...I have a video on it

[@86boostdcapri]

@@powellmachineinc ok the ones the places call "ls7" lol

[@86boostdcapri]

​@@powellmachineincso new gm lifters aren't as good of a design as the older style, in terms of oil band location?

[@michaelking3542]

What about anti pump up lifters?.......Great video's.......😎😎

[@powellmachineinc]

Snake oil

[@ItsCodaz]

Great video. Also watched your "DO ls7 lifters really exist" video. I'm new to building engines but my dads been around the block. I looked online and they said "ls7" lifters require .08-.100 preload. After watching both videos I now see this is false. Im just really stuck right now. So doing pushrod check at zero lash I got 7.235 Intake and 7.224 exhaust. You say the goal is 0.030-0.060 If I went with a 7.3 pushrod it makes intake preload 0.065 and exhaust 0.076 (outside of the .060 goal) But if I went 7.25 now intake and exhaust are under the goal. something like intake being 0.015 and exhaust 0.026 What would you recommend?

[@powellmachineinc]

7.3 would not be a deal breaker at all

[@ItsCodaz]

@@powellmachineinc awesome thanks boss! 🤝🏻

[@nickgarrett2533]

7 490 at zero is the longest I've seen yet. You obviously measured correctly, same way i do. Just was odd to hear that number since everyone ive done always falls into the 7.375, 7.400, 7.425 with preload added. Guess non milled heads and no block decking with a .05x head gasket and a small base circle cam there.

[@powellmachineinc]

It's because the head is tall, it has raised pads and longer valves

[@nickgarrett2533]

@@powellmachineinc ahh copy that. Just started watching your videos recently. Well informed and straight to the point. Nice to see someone take pride in their work. Keep it up and thanks for your knowledge

[@powellmachineinc]

@@nickgarrett2533 thank you! We really appreciate that

[@recoilrob324]

There is another fellow making KZbin videos (initials RH) doing a lot of dyno tests who claimed that the LS made more power with a longer pushrod. I asked him to explain HOW this could be....was it rocker geometry change or just the lifter slightly floating and increasing the effective duration? He got snotty with me (because he didn't know the answer) and just said 'It DOES'. I'm of the opinion like Mr Powell that less preload is better than more.

[@powellmachineinc]

Yup

[@dustinsamson4879]

Where is this shop located?

[@ViperMods_216]

Do you see a lot of issues with prc heads?

[@powellmachineinc]

Only the 2nd set thats ever been in my shop

[@MichaelOBoyle-x2p]

I love you debunking bullshit. I love your channel.

[@powellmachineinc]

Tyvm! We appreciate that

[@RANDOMNATION907]

Excellent information. Applicable to any pushrod equipped engine. side query: Are y'all gonna create an Odysee or Rumble channel? . . I'm trying to move away from anything google/yt, and if y'all were to do so, I would gladly watch your content over there. But, if you stick with yt, at least for now, I'll watch here. Either way, I'm still staying subscribed.

[@powellmachineinc]

Never heard of that?

[@frfrpr]

You can't skip math classes and expect to be a machinist. That's for sure.

[@powellmachineinc]

Absolutely

[@Anthony-nw5zv]

Exactly right 💯😊

[@6xcchamber971]

Your missing the rocker tray?

[@powellmachineinc]

@@6xcchamber971 no idea what that means

[@6xcchamber971]

@@powellmachineinc Rocker stand!

[@swede910]

Lifter travel has never been much of any use to start with. Why would you want to have a pump action that exceeds play plus material expansion!? 🙈 What is the expansion of an all alu compared to iron block, anyone know this?

[@powellmachineinc]

Many variables in how much lash grows, but .006-.015 is the average window depending on all variables

[@markokingo]

👍 Good stuff

[@powellmachineinc]

Thanks 👍

[@GeorgeFarahGNR]

Now, what about Short travel Johnsons vs reduced travel. The “internet” says you have to check every cylinder with Short travel. Why? Or is that even true. Any benefits to a short travel vs reduced travel vs stock style gatorman

[@powellmachineinc]

How much travel is "reduced travel "? How much is "short travel "? How much is your lifter bleeding in a cycle?

[@GeorgeFarahGNR]

@@powellmachineinc .058 plunger travel on short travel. Only info i can find quickly on “reduced” travel is .005 shorter than a “LS7” lifter and the ability to not bleed down as fast as an oem lifter. Both have the same recommended preload of .035 +/- .010

[@RoyOlsen-mm4fm]

Forget travel and run solid cam.

[@MrBigDeel]

Thanks for the video "Facebook Bob"

[@powellmachineinc]

You're welcome

[@swi9945]

Sounds like you need to be an engineer to build an LS? I have built dozens of SBC's without all this engineering. Was I just lucky that they all ran as expected? They were 327 or 350 from the 70's. Pink rods, trw 11.5 to 1 pistons and forged crank. Was I just lucky?

[@powellmachineinc]

The exact same principles apply to all engines, even more on a stud mounted rocker.

[@alanmeyers3957]

The point of the video, from what I understand is, set pushrod length for minimum preload.

[@swi9945]

@@alanmeyers3957 I don't get it, a hydraulic cam/lifter combo means you tighten the rocker down to zero lash then another 1/2 turn case closed. What use is there for different length push rods when the lifter self adjusts?

[@mikediamond1522]

Couldn't you put the pushrod in purposely short like you did, then put an indicator on top of the rocker just above the pushrod to get it pretty darn close, then go from there? You're going to wear out the screw prematurely and get autheritis. Mike

[@powellmachineinc]

Yes, it's just not as accurate

[@ryan8456]

Aren’t stocks push rods 7.380

[@powellmachineinc]

No

[@suicidal_racing]

they where 7.38" from factory, a ton of places sell factory replacements that are 7.4" though. ps yes I've measured multiple sets over a decade ago ( 7.38-7.385) is what i always got. gm even listed factory length as 7.38 in the org ls engine parts specs. this reminds me of the other 2 good ol ls valve train myths. i.e 1 turn is .050 preload and the other one of how ls lifters have 200" of plunger travel when in fact some gm ls7 lifters came with .126" of plunger travel.

[@HeadFlowInc]

#1 never run near “zero” preload unless the lifter has real steel clips! Never trust the cheap wire clips.

[@Calango741]

Ya need to fix the typo in the video title.

[@powellmachineinc]

Got it

[@Calango741]

Wow... that was quick. Well done.

[@Nastynati0513]

Makes sense as to why all the big LS cam companies sell whole cam kits with 7.400 pushrods. Obviously, every build is different, but in most cases, it's just some dude slapping a bigger cam and springs into a tired old vortec motor.

[@powellmachineinc]

Yup, unfortunately

[@patrickwendling6759]

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

[@powellmachineinc]

💯

[@charlesthomas2586]

Way too much talking🎉

[@powellmachineinc]

You don't have to watch....

[@charlesthomas2586]

@powellmachineinc i still like watchings 👀

[@scudzuki]

If you feel a little play in the rocker still, can't you measure the play with a dial indicator, then measure the length of the pushrod and add the measured play plus the desired preload? I do the same thing zeroing a rifle scope. If the bullet impact is 3.2 mils high, adjust the turret to plus 3.2 mils.

[@powellmachineinc]

Because od rocker ratio it's not as accurate, but yes