LS PUSHROD LENGTH TEST-IS LONGER STRONGER?

[@BadLuckGarage]

Preload is the word you're looking for brother. In a bolt down rocker setup, changing pushroad length is the only way to add preload. Same thing you used to do on small block Chevys by putting that extra half or 3/4 turn on the nut when adjusting the rocker arms past spec. Cant do it on an LS so you just run a longer pushrod instead.

[@douglash3129]

Are we having fun or what!!! Thanks Richard!!

[@jasonhaley5737]

Stock Eliminator trick. You're shortening the column of oil in the lifter. Cool test!

[@MyLonewolf25]

Didn’t those guys also take lifters apart and shim them so they couldn’t collapse?

[@chettrockwell]

@@MyLonewolf25 ....maybe.....🤐

[@Motor-City-Mike]

@@MyLonewolf25 Sure did - left just enough travel so the weren't completely solid.

[@someguy325es]

@@MyLonewolf25 I do this in BMW inline 6's. I get hardened shims made the right diameter to go inside the stock hydraulic bucket lifters. I remove the check ball and spring from the inside to disable them and set the lash with the shims. Running mine at 9000 rpms.

[@drakeolson2539]

Man, This has never crossed my mind!!! Man I love This channel!!!!

[@kylemilligan752]

The big takeaway. With rpm, engines whip air into the oil. When oil mixed with air finds its way to the lifters, they collapse. Much like having air in your brake hydraulic system. Hydraulic lifters cannot transfer camshaft events to the valve when there is air in the lifter. Longer pushrods just reduce the volume of oil and air under the piston in the lifter. Less room to compress.

[@hotrodray6802]

That is what he said

[@vikenlink]

Might as well just go solid lifters….. but that’s a 3000 mile annual repeat valve to rocker arm adjustment, not to mention adjustable roller rockers, oh no more $$$$$. What do you mean I need taller rocker covers too and maybe longer ignition wires. The good and bad of hydraulic lifters. Putting in 7.50 pushrods really increased hp and torque very noticeably. Makes me realize I have more room for a bigger cam without sacrificing drivability in a automatic. I have a BTR Stage 2 N/A LS3 cam in my 416 stroker. Idle is very tame at 850 rpm without much chop if any at idle, actually very smooth. BTR hasn’t come out with the LS3 V2 of the stage 2 or stage 3 LS3 cam. I think Brian discovered more power potential using the spinnes sprone.. I think that’s how it’s spelled lol.

[@Airman..]

Very informative i have swerved from many unnecessary modifications Thanks to you

[@sircrashalot90]

Imagine this coming out on LS1tech 10 years ago 🤯

[@MultiScotty12345]

Perfect timing for this video. This will help me determine my pushrod length for my new cam in my LS6

[@jeffpittman8725]

Excited to see what's next with the Caddy, Buick and the 4.9L Ford!

[@HiShBL2]

The trickflow heads have 13.5 degrees valve angle which requires a longer pushrod and the 7.500 is what should be used with that setup , a stock unmilled heads would be good for a test . Thanks for the test Richard .

[@mauricecooper176]

You got me with the thumbnail only thing missing is a knitted sweater lol

[@blackthunder7342]

You should make a coffee table book with all your tests with pictures and dyno scales that would be awesome

[@thirdgearpull3gp975]

I love all the tests you do Information like this is gold

[@billashe2108]

Excellent explanation as always!

[@dondotterer24]

I remember when my dad put and old GM Corvette factory solid lifter cam in he's wood hauling truck. We ran the valve lash at 20 exhaust and 18 on intake. I thought he was crazy but made good power and torque and revved guick. But without poly locks we had to adjust it alot.

[@prestonedmonds4128]

Have you tested solid roller lifters on a 5.3 vs. hydraulic rollers. I love solid rollers on my SBC's even on the street. This test reminds me of reading a David Vizard book 20 years ago about finding small amounts of hp. He would set the valves while the engine is running and keep tightening until the engine misses and the backing off slightly until the engine clears up. This takes up as much slack (travel) in the lifters as possible.

[@calebgrant7176]

Pretty smart

[@cameron878]

Always answering questions I didn’t know I had! Nice work Richard!

[@dryforkdieselandauto1011]

Always wondered why pushing the lifter plunger down in bore made power and totally forgot about oil being aerated with air. It’s the air in the lifter bore oil compressing effectively shortening the duration and lift a bit.

[@hotrodray6802]

Years ago experts insisted that running hyd lifters as long as possible (1/4 turn preload) was the best. Now we need to run them 1/4 off the bottom. My how ideas change.👍

[@656hookemhorns]

It's almost like running a solid lifter, but with out the headache of lash adjustments. I would guess if the pushrod length was just right you could be within a few HP of a solid lifter setup, but without fuss.

[@richardholdener1727]

hydraulics often make more if the cam is the same (hyd doesn't have lash)

[@prestonedmonds4128]

@@richardholdener1727 how does this happen when there's more cushion in the lifters? Plus, aren't the solid lifters more controllable because of their weight advantage?

[@timothybayliss6680]

@@prestonedmonds4128 hydraulic lifters take up some of the valve lift, a tight lifter might lose .005 valve lift under the best circumstances, bad ones with hard valves springs will lose more. It gets worse as the oil gets aerated at high rpm. Something like this, with double spring and 6k rpm, it's probably losing .020 lift or more at the valve. You could put solid lifters in and adjustable pushrods and duplicate the power curve to get an accurate guess. A solid cam is always going to have lash and rarely is it going to be less than the hydraulic deflection. Solid cams can have faster ramps because the lifters are.lighters and there isn't a hydraulic element that can limit valve spring pressure. When you have a ton of spring pressure it can play havoc with hydraulic lifters. Kinda why street solid rollers have fallen out of favor. When you can get 7000rpm blasts out of something with factory lifters and really low maintenance, solid rollers get left on the shelf for proper race cars and really hardcore guys.

[@ldnwholesale8552]

A good hydraulic roller with the CORRECT valve geometry is near as good as a race type solid roller. Better for street applications always. But the solid cam will make more top end power!

[@jeremypike9153]

A spintron machine is what you want to be able to fine tune your valve train Nascar engine builders and top fuel builders have started to use them over the last 5 years. A properly tuned or optimized valve train as a package will make the most of whatever engine its installed on. A dyno can only measure engine output a spintron works the opposite it spins the motor over allowing for measurement of valve bounce or pushrod deflection.

[@r.h.5052]

I'd think the shorter pushrods also causing a delay in valve opening until the compressed amount can overcome the spring pressure.

[@xnotx2]

That was my thought too. With a shorter pushrod at low RPM, you're getting an effect of increased cyl compression ratio due to more a depressable lifter (lower oil pressure, more air). At high RPM's, especially with the longer pushrod, you're getting the effect of more lift, and sooner due to less compressible air volume inside of the lifter.

[@hydrocarbon82]

The cam guy mentioned aerated oil in the lifter. If the oil was 100% loquid, it wouldn't compress & act like a solid lifter. Due to leakage & air, it compresses some before it balances out and movs the valve. The spring pressure just determines how much that lifter compresses. Reduce the aerated oil volume by pre-compressing (preload) and it moves the valve sooner. The net effect is like adding a tiny bit of lift all over, which increases duration. That's why it kills a little down low and increases power up high.

[@jimkillen1065]

Well lol I was going to suggest installing limiters in the lifters as I do in my SS motors . I seen these conversations before but one thing that was suggested not sure if its true is if you adjust the lifter with adjustable push rods or some other method to the bottom of travel it may effect the oil delivery to the top end . I use limiters . A good test might also be a swap on a motor between solid and hydraulic on one of the performance builds . I found out many years ago to try different lash settings on the Isky Roller cam and it made a big difference . Thanks for the videos

[@howardfry419]

I sent my comments before the end of your test.

[@mindtouchone]

Do a video on checking and setting the rocker arm geometry by using different length pushrods. Correct geometry can reduce friction between the valves and guides. I've been building and tuning engines since the 1960s and way back then someone taught me how to pick up 500 rpm with my hydraulic lifter, 340 horse 63 Impala 409. With the engine running I backed off each adjustment nut until the rocker arm clicked and then tightened the nut 1/8 a turn. This allowed 6000 rpm instead of the stock 5500 rpm. With the 4.56 diff the car had the engine got there quickly. Over and over for years I power shifted this car with 0 engine problems.

[@richardholdener1727]

There is no change in rocker geometry on the ls with a change in pushrod length-it is a bolt-down rocker

[@mindtouchone]

@@richardholdener1727 I wasn't talking about this video, I was talking about a new one about checking geometry and correcting it if needed. This is a little known procedure. For the last 10 years of my career I taught High Performance engine machining and building and dyno testing and tuning at a tech college and many of our students got great jobs. We had the best machines for them including Sunnen Seat and Guide machines and other state of the art gear. Rocker Arm geometry was nor part of the course but sometimes I would show that to students who wanted to excel. With that said I love your videos and I am jealous - I wish I could do what you do, it would be so much fun.

[@brandonpayne1207]

So what you're saying is drive around daily with shorter lifter and when you go to the track, swap them out for longer ones.

[@richardb7977]

How about a roller rocker test? 1.7 vs 1.8 on an LS.

[@crw3673]

Definitely worth testing!

[@DBSSTEELER]

10HP. It’s been done.

[@Dr_Xyzt]

The stock rockers are already like roller rockers. The tip of the rocker has a curve. It naturally rolls on the valve stem instead of sliding. Pretty trick pieces.

[@richardholdener1727]

rocker vid is up

[@ldnwholesale8552]

The ONLY time I have ever used expensive pushrods is because they were compatible with the guide plates. The old Manley plastic guide plates were great. Or the bronze sleeve style. And simply use OEM or Speedpro ball end pushrods. Chevs, Fords and Holdens. Even race rollers.

[@markbuskens6070]

Man great test!!! You never disappoint us, only thing I ever thought on pushrod length was correct rockerarm to valve tip geometry as the valve went up and down... contact patch.I knew the stock Ls pushrods were weak and knew about pushrods flexing too.great test!!! I believe your test with different heads and cam profile would change results on the short and long combinations.Great test!!!👍👍👍

[@richardholdener1727]

contact patch does not change-rocker position is fixed

[@markbuskens6070]

Richard Holdener on a small block with adjustable rockerarms

[@460FORDMAV]

Very good video....never think this will happen! Richard...we talk a lot about windage....what do you think about trying to install a camera inside the engine and try to see the results of no tray vs tray....something like this.... I know it is not an easy one but also a interesting idea. Take care

[@Smoked_5L]

Super interesting! would love to see that lifter video!! Maybe you can do sn ultimate guide to lifters in LS applications!

[@yinzer_412_]

I did basically the same thing when I went to 1.8 rockers from 1.7 on my ls3. The comp ultra pro magnum roller tip rockers were a direct replacement from my stock rockers without replacing the stock length pushrods. Albeit they collapsed the lifters .115 - .118 I didn't sweat it because I had plenty of valve to piston clearance and I knew you can preload an LS7 lifter .200 no problem.

[@yinzer_412_]

Those wanting to know LS rocker bolt 8mm x 1.25 = 20.32 threads per inch 1”/ 20.32 = .0492 trunion movement per turn of the rocker retainer .0492 applied to appropriate formula=.078 lifter preload per turn for a (1.7) rocker .0492 applied to appropriate formula =.076 lifter preload per turn for a (1.8) rocker

[@curtisanderson9984]

Great test. I never considered that.

[@remybrouwer8700]

Yes definately like to see that test with a standard lifter vs a cheater/short travel lifter, it will be like the same result I suspect, but what about doing this test just changing the lifters and see where valve instability starts and then change the springs and see how much range of rpm is gained before valve instability shows it self again.

[@mxguy2438]

Interesting video! How about a test on high pressure and high volume oil pumps. More airation? Lifter pump up? A test on Rhodes lifters would also be cool. Imagine what oil airation does to your bearings at higher power levels.

[@YZFoFittie]

The limit of pushrod length is when you bottom out the plunger once the engine is warm. Any amount of oil in the lifter will prevent this...

[@arturozarate1752]

Good test Holdener.

[@ultraworks1]

Thank you for this !!!!!!

[@hotrodray6802]

And dont forget.... The length of the pushrod affects the position of the rocker arm tip arc in relation to the valve tip. Valve lift is affected by a few thousandths, though not as much as the lifter piston position. The lifter aireation also affects your dyno power graphs midrange with dips and bumps as well as drop off "float". JMT 😎

[@richardholdener1727]

pushrod length has not effect on rocker tip position-rocker is not adjustable

[@shredfest30]

@@richardholdener1727 Yes it absolutely does. when you start your rocker arc at a low position, the efficiency of lift is nowhere near as direct as it is at exactly level.the sweeping action is theoretically changing the ramp rate, and ultimately the valve stem speed throughout the lift range. this was proven 50 years ago with a GM engineer (Ralph Johnson) on a solid cam small block, where there was no oil in any part of the equation. kzbin.info/www/bejne/iJvEoKaOa5h3oa8

[@michaelmoore6186]

You should run 7.50 pushrods on the intake valves and 7.40's on the exhaust. Better yet run that combination on number 1, 4, 6 and 7 cylinders and 7.50's on 2, 3, 5, and 8! 😀

[@bowhite1293]

Thanx for another great test Richard!

[@hotrodray6802]

Years ago experts insisted that running hyd lifters as long as possible (1/4 turn preload) was the best. Now we need to run them 1/4 off the bottom. My how ideas change.👍

[@mxguy2438]

Running minimal preload made a significant difference in idle quality and made tuning easier on early efi systems but now i wonder if it cost power. I wish Richard would talk more about idle, low rpm and surge characteristics in his videos.

[@chrisreynolds6520]

My 350 Vortec made alot more torque with 1/4 turn preload. Same HP up top.

[@georgem.6136]

Very cool test!

[@Airman..]

More testing please 🙏

[@smiller225]

You are gonna make me buy some 7.45 pushrods

[@bobmcalister2131]

Short travel is better all ready been there lol... great videos man keep it up!!!!

[@bartpang]

A point of interest, shorter pushrods (with adjustable valvetrain) can turn more rpm before valve float but at the detriment to valve guides.

[@Crysmatic]

pushrod stiffness goes up with increasing diameter...thickness barely does anything. weight doesn't matter much...stiffness rules at high rpm. but this is a cheap trick to increase stability at higher rpm. thanks!

[@ShawnDickens]

Thickness changes harmonic, so if you have a harmonic issue you can thicken it and push it up in the revs above your use range.

[@milojanis4901]

That is incorrect. Physics tells us if you double wall thickness, the yield strength is now 4x what the original thickness was. It is an exponential increase, not a linear increase.....

[@lloydholt6511]

Great test. After thinking about it for a few seconds I came up with the same results. Had the benefit of a previous tv show which played with setting valve lash on a small block 383 hydraulic cam. As the lifter was compressed more the engine responded similarly to you longer pushrod lengths in the ls series engine. Thanks for the video. You always make people think. That’s a good thing.

[@dondotterer24]

Please test th Rhoads lifters on LS and SBC with different valve lashes on the SBC of course .

[@lancecooper4646]

Yeah, I second that, would luv to see how they compare to a standard hydraulic lifter, especially with big cam 👍

[@Apachefog]

Good to know if I run slightly thinner head gaskets that I don't need to worry about pushrod length.

[@AlexLTDLX]

Ok, this is super trick. So if I tighten up my adjustable rockers, I could see similar gains? Thanks for another awesome video!

[@johndelta00]

I was gonna leave a smartass remark then I recognized your username. I've followed your ltd build for like 8 years, me and a buddy tried doing the same blower set up on his ranger but he is a lazy fuck and never finished the "adapter".

[@creepycrawler43]

Another great video man, love learning cool motor stuff

[@jeffturner6330]

Great vid as always

[@hot355clubby]

Richard what would the same test on a solid cammed engine with non bolt down rockers result in? How would different pushrod lengths affect power production? Keep up the good work 👌

[@richardholdener1727]

adjustable rockers would change the contact patch and geometry with different pushrod lengths

[@hotrodswoodshed7405]

Thx so much for giving detailed info on pushrod length. In your test the lash was directly affected by rod length, giving the results in power... HOWEVER , with a adjustable rocker im curious if the power change results would be similar because of simple slight geometry changes that also happen with different pushrod length?? In other words... could the same small dyno numbers happen on adjustable rocker engines because of the affected rocker geometry???... as opposed to the lash in your example

[@richardholdener1727]

there is no lash in a hydraulic roller motor (only lifter preload) adj valve trains on solid cams are different

[@fascistpedant758]

IIRC, GM rocker adjustment spec on the sbc was 1.5 turns after 0 lash. I've been hearing YT "experts" say 1/2 turn is better for strange reasons. This sort of contradicts them. The extra turn will compress the lifter an extra 1/16". Thanks.

[@jeffreydurham5342]

Strange reasons were to prevent or limit "pump up" when the spring could no longer control the valve, thus giving more rpm.

[@BadLuckGarage]

We always went an EXTRA 1/2 turn PAST spec to increase preload on the small block chevys. Not a 1/2 turn past zero lash. Effectivley accomplishing the exact same thing Richard is with the LS by using longer pushrods. Its just adding preload to the lifter.

[@XWilkaX]

Maybe on your short vs standard travel test you can explain the importance of lifter preload and how it effects lifter health and valve events and their relationship

[@richardholdener1727]

my test wasn't on lifter life

[@XWilkaX]

@@richardholdener1727 I know but alot of people just go slap anything in and wonder why their lifter failed.

[@timothybayliss6680]

I like this test, nice data and repeatable. The only thing you didn't mention is possibly exasperating valve float. I remember a test years ago in CC where they tested an RB Mopar with adjustable pushrods. The results were similar but when they tighened the lifter preload to near the bottom of travel, the valves would float earlier. I am wondering what would happen if you repeated the test with an ls3 up to 7000rpm, some of them will float the valves at 6200rpm.

[@fascistpedant758]

Valve float could have been a result of the adjustable rods being heavier.

[@Lagrange1186]

Is this the same 5.3 stroker you ran back in the day with the holley 300-120 intake and two 390 carbs? I can only read about it and can never find the pictures of the dyno results... any chance you could talk more about your 383 stroker LS combos? Seems like one heck of a sleeper engine!

[@tfrthomasfamilyracing3662]

What was the amount of lifter preload? I would like to know the range. Did you start at .070" and increase making the range .070" - .170"?

[@alexanderknight7793]

This is what we REALLY should actually be discussing.

[@robertkeime4907]

Great video

[@seahorse5677]

Sure you increase the preload on the lifter, but the power increase from longer pushrods is the function of an increased the rocker ratio. Longer pushrods simply push the valve open further.

[@richardholdener1727]

that is incorrect-the pushrod length has no effect on rocker ratio

[@seahorse5677]

@@richardholdener1727 Could you explain? It's mechanical principle that if the effort side of a lever changes, there will always be a consequence to the load side. It's also measurable on the valve. 100% of the time when you change the pushrod length, you get a different valve lift reading. kzbin.info/www/bejne/iJvEoKaOa5h3oa8

[@TheNumbers400]

Hey Richard have you ever published the dyno graphs from the "Speed Secrets: The BTR Blower Cam made HOW MUCH??" video? Your comparison on stage 1,2 and 3 truck cams was great. Have you ever done a stage comparison on different PDS cams?

[@richardholdener1727]

I'm sure I did

[@atf0013]

When I went to Lunati link bar lifers with the stock cam and stock rockers I had to run 7.35" instead of stock 7.4" due to misfires on 2 of the cylinders. This was because the LS7 and other aftermarket lifters were not the same height as the original LS2 lifters.

[@vans1107]

what was the reason for the misfire? holding the valves open slightly?

[@davidciesielski8251]

Hi, I really want to thank you for this. I had no idea........................

[@chucksmith7166]

No it all has to do with the base circle of the pivoting rocker arm. If you start it’s movement before or aft you can trick the rocker arm in to thinking it has a higher ratio or a lower ratio. It all depends on where it starts it’s movement in its base circle!!!

[@richardholdener1727]

there is no change in the pivot of the rocker-its fixed (its bolted down)

[@ZackNakazora1]

So... Run a slightly longer hardened rod and reap the rewards? The torque dip down low low doesn't really matter when the vehicle is up and moving. And if longevity isn't an issue. That's just free hp

[@timothybayliss6680]

You usually don't need hardened pushrods unless you're running guideplates. The factory rockers don't need hardened pushrods but there might not even be a difference in cost. All of these pushrods were probably off the shelf items where I can't even find aftermarket pushrods that aren't heat treated or hardened.

[@ZackNakazora1]

@@timothybayliss6680 yeah I agree. Like it's a selling point to the part finding an unhardened rod oe replacement? Might not even be worth it price wise. I'll be punching at least a. 600 lift

[@hotrodray6802]

The dyno torque dips down low are irrelavant for the first 300 rpm because of the dyno load tip in. RH did a graph of 2 overlapping pulls back to back on the same same engine, one 2-5000 and 5-8000 and the graph overlap at 5000 showed the tip in load difference. The first 300 rpm is irrelevant.

[@Coremanator]

What does the longer push rod do to longevity of the valve train?

[@approachingtarget.4503]

Your increasing valve lift and duration. The lifter doesnt move anything until the plunger reaches full compression. Longers rod will increase both. A hydrolic version like roads lifters would bleed off the oil in lifter at low rpms. Then become more stable as the oil pressure increases. Longer rods bend easier and add weight to the valve train. Compare it to another non adjustable engine family like the dodge power plants. Push rods are solid since oil is pumped into rocker shaft. Another comparison is lash on a solid lifter. Less lash means more lift and duration. Obviously has some limits. Question for you! How much can you change cam lift and duration on a mopar with bleed down mushroom lifters. Would you be supprised to be able to change the corrector of a power plant by simply changing oil pressure?

[@andyharman3022]

Wrong. The lifter starts lifting the valve when the check ball closes. The column of oil in the lifter carries the valvetrain load.

[@genemounce8302]

Sounds like you need some Sudafed cold/flu...or a shot of whiskey. :) LOL

[@milojanis4901]

Interesting. I have an LS7. It comes standard with 7.800 length pushrods. Wondering if I should try 7.85, or maybe 7.875? I believe the 7.800 stock length pushrods put the lifter cup exactly halfway through its travel range, which I'm told is .150-.160". Any ideas?

[@rorydottin7143]

Results on pushrod length variation with LS solid roller engine.

[@LC-fl3zm]

thank you

[@DBSSTEELER]

When you think about it changing the pushrod length on an LS application is kind of like changing the lash on a solid roller cam.

[@hotrodray6802]

No, solid lash is a fixed amount except for heat expansion. Hydraulic lifter the oil keeps the lash consistent except for aireation and pump up.

[@davidanderson6706]

Yo Richard you gonna show the dyno graph of the standard 5.3 so we can all see????. do a quick video of it with the 80's porn music in the back ground. Because thats what we want

[@deanstevenson6527]

David Anderson : Aint no accounting fer taste Mr Anderson. Kant Komplain without m...m...music....

[@jasperlit1345]

Hey Richard, have you ever done a connecting rod length test? as in longer connecting rod but a piston with a higher wrist pin location so same bore/stroke but longer connecting rod.. any mechanical advantage/disadvantage? Hey AWESOME CHANNEL!!

[@jeffreydurham5342]

On paper a longer rod seems to be an advantage. Reher Morrison said absolutely no advantage in longer rods. Jon Kasse says 2 inch longer than stroke!

[@timothybayliss6680]

For power output there really isn't a difference, longer rod engines are more mechanically efficient but it comes at a cost of reduced pumping efficiency. The net output is almost no change in power. There is very few engines today with a r/s ratio under 1.6. They scrub the cylinders hard and CAFE standards are always tightening waistbands.

[@richardholdener1727]

yes-I compared a 5.7 vs 6.0 rod on a SBC-no change in power

[@johnduran6989]

Richard do you ever sell your project motors? I'm needing mild modification 5.3 or 6.0 for 2013 suburban. I love your show. I just live small town and am limited on mechanics who are more than part swappers. I can give you my 5.3 220k burns oil

[@richardholdener1727]

I do not but have something cool coming up for Patreon that might interest you

[@johnduran6989]

Looking forward to details

[@rkmorgan2052]

Like it so you can change power range simple at the track shorter more bottom end longer more on the top and if that wasn’t enough swap a longer on the exhaust or intake for fine tuning.... guess it all goes by preferences or whatever the track will hold

[@timothybayliss6680]

These are really minor changes, like tiny. I would be surprised if someone ran back to back runs in the same car and would even notice. Even at the drag strip you would be looking for like .05, but probably more like .02 on a run.

[@james10739]

So I believe you said ls7 lifters are short travel or something but should we all be going out and putting ls7 lifters in out engines

[@drpepr96]

Yes

[@evcass69]

I believe ls7 lifter preload is designed to be .060-.100", short travel is generally about .035". That's after accounting for any heat expansion in an AL block that will reduce preload.

[@stevethomas1301]

Hey Richard. Its time to play with valve lash on Solid cams. I expected similar results as this test but maybe more extreme?

[@lety2467]

Hi Richard, It would be nice to know what lifters you were running in this engine, and what the resulting preload was when you used a 7.4 vs a 7.5. I did not catch that in this video, if you still have that data please do share! Wondering how good of an idea it is to run a hydraulic lifter close to its travel limits. Maybe you still had plenty of room to spare?

[@richardholdener1727]

longer pushrods eliminate the aerated oil in the lifter and make it act more like a solid.

[@lety2467]

@@richardholdener1727 Hi thanks for the reply! Yes I understand that part. I was curious how close this test took you to the limits of preload on your lifters. I am guessing you were running Delphi LS7 lifters since you managed to get .150" worth of preload out of them. Probably not a Morel or a Caddy race lifter? :) This was an interesting test but maybe with the caveat that pushing these lifters so close to their min and max capable preloads might not be a great thing for a street engine? But it did give the clearest results to interpret on the dyno curve so as to understand what is happening? I'm setting up a street 6.0 right now and I will try splitting the preload as you did in your last test..in my case ~.059 preload on IN and ~.084 on EX. This on Morel lifters with .120 of total preload travel and recommended target of .060 preload. So I am not going to quite the extremes this test did. We'll see how it runs?!Cam is not extreme, plenty of PTV clearance.

[@kellybrown1860]

good stuff

[@Levibetz]

Have you done any tests where you toss hydraulic lifters on a "solid lifter" cam? Or the sloppy solid lifter where you pack washers into a hydro?

[@knowbull5hit590]

Oh we need to see these tests forsure. doing things for cheap, that really shouldnt be done, to make power are always interesting

[@Levibetz]

@@knowbull5hit590 I've heard of circle trackers doing it to cheat up some hydraulic lifters

[@bill2178]

It would be interesting to know the effects of crankcase vacuum on the aeration of the oil with these different pushrod length

[@evcass69]

Yes, please, LS oem lifter vs Johnson st2126lsr vs solid lifter and rev it to the moon with an adequate valvetrain. What happens if you use a solid roller cam with the ST lifter?

[@aquapneumatics]

It is changing rocker arm geometry. You can get those results if your geometry is off in the first place.

[@richardholdener1727]

rocker geometry is not changed with a bolt down (in the same location)

[@frankrobinson2895]

Do you have data on the effect of changing connecting rod length (all else held equal except piston wrist pin location to compensate compression ratio)? My engine builder says it doesn't matter, theory says it does.

[@gtbmjb7192]

So for a stock LS2 the increases would barely noticeable, correct? Great job by the way.

[@richardholdener1727]

That is correct

[@Farmtruck62]

In all reality the longer push rod is putting more preload into the lifter. If the push rod is deep enough, as RPM increases, the lifter bleeds down to the point where it becomes a solid creating more power on the top end.

[@tbl8560]

Is lifter pump up really a thing? I don't think so. You have 60psi of oil pressure pushing against a .700" dia lifter piston which equates to net 23psi which is pushing against 130psi valve spring seat pressure not to mention +300psi open pressure. Valves opening/floating is just a lack of spring pressure to control valve train.

[@danielsimpson8929]

Did you th8nk to do intake only and keep exhaust at 7.4? Or 7.35? Wondering what curve changes you get as well as fuel consumption. Thanks.

[@vonnsnyder2481]

Awesome!!

[@james10739]

I don't know if tou still have these old videos saved on your end but it looks like they only have 1 resolution and the resolution says unavailable i assume its youtubes fault because 4 years ago people were definitely uploading videos in like 1080p and they would let you select everything up to that

[@Turbogto_guy]

So what I fail to understand is, did you setup the “correct” length first? You know, using a length checker, then putting those pushrods in? I have a hard time thinking a cam that large the length would be “correct” with stock length pushrods. So maybe the 7.4 were just too short and the 7.5 put it in the correct realm? Why has no one else mentioned this?

[@iraadams7459]

The base circle of the cam is the same no matter how much lift it has. Since there's no adjustment on the rocker arm, the distance between the lifter and rocker arm doesn't change, so the stock length still works.

[@Turbogto_guy]

Ira Adams 100% incorrect. I’m pretty well educated on camshafts too. I used to work at a well known company that made cams. I’ve worked every operation on making a camshaft except final grinding and finishing. I’ve built numerous engines. When I put the first cam in my gto, I used stock length pushrods because someone like you told me it would work. I knew better but was being lazy. It had so much valvetrain slack I couldn’t bear to listen to it run. Ended up checking them and I needed 7.500 pushrods. No other changes besides a cam. So you are definitely incorrect. The extra lift comes from a smaller base circle.

[@zibagoolie]

Yup, I was wondering the same thing. Kinda surprised @RichardHoldener didn’t mention it/do it.

[@zibagoolie]

Also, besides the smaller base circle, this was a stroker motor that they machined. If it was decked and or heads milled length would be different also.

[@Turbogto_guy]

zibagoolie exactly. So how is this test even relevant if the proper lash has not been established first? Of course if the pushrods were too short that would see a loss in power and then putting the preload in the correct spot would give the power back. Without explaining if the correct preload was set, from the beginning, then there’s that what if hanging out there. I know mine didn’t even want to idle with the shorter pushrods. When I set them to the correct preload, it idled fine.

[@TractorWrangler01]

You are reducing your valve lash and creating more lift and making your valves open slightly further, almost like adding lift to the cam. Beware the potential catostrophic damage possible in playing with this. Interesting test. When you run out of pumping mecanism in the lifter the valve will no longer close fully, resulting in burnt valves or worse. If youre thinking about playing with this you should just consider mechanical lifters instead.

[@richardholdener1727]

there is no lash

[@TractorWrangler01]

@@richardholdener1727 Yes I understand the hydrologic lifters have no actual lash but the longer the push rod the less space is left in the lifter. When that space is gone and the pumping mechanism is bottomed out it starts functioning like a solid lifter.

[@jamest.5001]

Longer pushrod takes the oil cushion out of the lifter, I thought you knew this! It makes the valve follow the cam more closely.

[@jcnpresser]

I was guessing this is why the extra power, but I think it’s because once the lifter rises passed the oil passage in the lifter body it has no place to go, this adding more lift and duration to the valve.

[@gtbmjb7192]

Great test as always, thanks. Is the 7.5 the maximum length on a stock LS2? Regards,

[@richardholdener1727]

DEPENDS ON HEAD

[@gtbmjb7192]

@@richardholdener1727 sorry, asking about the "243" c6 corvette

[@gtbmjb7192]

@@richardholdener1727 Yes sir, what pushrod length is maximum for the LS2 "243" head on a c6 corvette, Thank you.

[@nsmturbo5902]

@@gtbmjb7192 too many variables, you need to measure. An adjustable pushrod is cheap! Machined heads/deck will change length, worn cam lobes will change length, worn rockers will change length, worn lifters will change length etc.etc..etc...

[@th600mike3]

I would be really interested to see you test pushrod length on a turbo motor. Especially running a normal (mid hydraulic lifter preload) on intake, and "long" on exhaust. On a wide lsa wouldn't it help open up the valve an add a bit more overlap? And help spool? Edit watched the video. My thoughts are that this should be repeated on wide and narrow lsa cams to see just how far that extra pre load goes. A short travel lifter would be interesting too. But I suspect good engine builders bake this into their builds to get that last little bit for turbo motors etc

[@howardfry419]

Wouldn't the Lifter take some of the length , internally? To what extent?

[@AdamOpheim]

What were the actual number gains? Seems like a very cheap easy thing to do to gain what looks like 26+hp on the graph going from the 7.4 to 7.5?

[@bfiman1]

Would this work with AFM lifters? Or would it not be worth doing with a stock motor, regardless of AFM, because the stock cams are so small? Maybe this, in combination with a rocker arm ratio increase, could make a stock cam think it was bigger?