LS Pushrod Length How-To

[@jmmiller7560]

While this is a good video for its intended application of stock rockers; many of its points cannot be used when upgrading to roller tip rocker arms, where MID-LIFT geometry must be used. There are a lot of videos out on roller tip rocker geometry that is completely misleading on the priorities of what should be checked, how to set, and what their effects are. For those who fall into this more high end application of rocker geometry for any of the LS series engines, please find the following comments helpful. > You NEVER want to worry about where the wear pattern is at on the valve to set rocker geometry. The wear pattern has NOTHING to do with "geometry." Because none of the manufacturers have any "accurate" standards for stud and stand mount dimensions from the valve, and because the stud leans into the valve, and because engine builders use varying length valves, and lastly, because every custom engine has a different NET valve lift, no rocker arm is going to be able to have the exact length required (on a mass produced basis) to accommodate all these variables. That is why you shouldn't worry about where the witness mark on the valve tip is at. Just worry about the angles. The BEST way to assure you are measuring ANGLES correctly with HARD measurements, is to use the VALVE SPRING RETAINER, because it is perfectly mounted at a 90 degree angle to the valve, and that is the principle of MID-LIFT precision. > You NEVER want to use "checking springs" to set rocker geometry. You need to check for NET valve lift with ACTUAL springs. Once you know what your NET valve lift is, then EVERYTHING after that is done with a CLOSED valve, no tension on the valve train; not even necessary to have an adjuster in place. Just an adjustable push-rod; dial calipers and KNOWLEDGE. > With all the tools I've made; and all the engines I've built; and all the tricks I've learned (many from other creative engine builders), to this day when I still occasionally help an old friend out on setting up his rocker geometry, I do it in less than 5 minutes with the following technique. It's all done in the CLOSED VALVE position, because you don't need to worry about hydraulic lifter valve compression or flex. You don't even need to have the adjuster on the rocker arm; it is all laying loose. And obviously, unlike this video, you are not rotating the whole thing over under valve spring pressure. Once you know what your NET valve lift is, everything after that is math, and setup; and this can all be done with the rocker laying loose on the stud, and an adjustable push-rod lifting or lower it as needed. > It's not complicated: A. Know your NET valve lift; divide in two; that is your MID-LIFT "motion" (MLM). B. Measure the height of your valve tip above the retainer. C. Measure the diameter of the roller; divide in half (this precisely gets you from the bottom of the roller to the AXIS). D. ADD "B" and "C" together, to get the STACK HEIGHT. An illustration can be found at: www.mid-lift.com/TECH/TECH-Installed-G1.htm E. Now, use a straight edge like the little machinist square shown in this video, and lay it across the valve spring retainer and alongside the trunnion. F. SUBTRACT or ADD (as needed) the STACK HEIGHT to or from your MID-LIFT MOTION, by raising or lowering the rocker arm on the stud. > EXAMPLE: * NET VALVE LIFT IS .700", so MID-LIFT MOTION is .350". That's cut in stone, now forget it for the moment (you've written it down). * Valve tip is .050" above the top of the retainer; and the .500" rocker arm roller diameter tells you its radius is .250", so the STACK HEIGHT is .300". SOLUTION: If the STACK HEIGHT is .300" and the MLM is .350", then you need to place the trunnion .050" BELOW the valve spring retainer. If your math has the inversion of this, then your trunnion centerline would be above the straight edge coming off the retainer. SUMMARY: DO EVERYTHING IN THE CLOSED VALVE POSITION, AFTER YOU KNOW NET LIFT. It's much easier to get an accurate DIAL CALIPER measurement on hard points, to find their true center-lines, than trying to use visuals that only give you approximate values. You can use the outer edges of the trunnion's diameter and divide in two for its center, which is far more accurate than eye-balling. For those who want to know what is important, and how to fix existing systems, you can get the book on this at: www.mid-lift.com/MID-LIFT_ARAT-2016.htm It's this simple: KNOW YOUR MLM; KNOW YOUR STACK HEIGHT; USE THE RETAINER AT CLOSED VALVE; and SET YOUR ROCKER TRUNNION as needed. Good luck to all. --Jim Miller

[@raho24781]

Hi Thank you for Sharing your Knowledge. I have a LS1 Heads Deck height .001 Head gasket Thickness .039 H Beams Probe Forged Pistons 596 605 lift ,motor was built for Lajuana Seca Button Willow, that type of track motor ,anyways had prw aluminum rockers and it broke one ,and the trunnion coming out of another ,got a set of TS steel roller rockers ,and pushrod length checker . TS foot note is check PR Length cause there usually .175 shorter ,,,so the ones i pulled out where 7.4 i put the length checker in and got 7.2 Zero Lash on the base circle then rolled it out 3/4 turn and set the Torque wrench at 25Ft Lbs.and it clickes off at 1/2 turn so I turned it in 1/4 turn and it Clicked off at 3/4's of a turn so i ordered 7.225 Push rods TS's Rockers are 1.72.1 Ratio ,and from what i got ,or Understand i should be ok ,,,,175 Minus .4 is 225 anyway .and have tried other scenarios. i dont know what lifters the Machinist originally used ,and he actually forgot ,the motor was built and finished in 2010 and sat on a shelf fresh never ran ,until i installed it myself ,,,I have already ordered 7.225 Length ,,,,will i be ok

[@highperformancecult]

That sounds about right, just double check when your new pushrods come in. As I mentioned some are spot on the measurement, and some are .012” longer. Use the bolt turn method. Since you don’t know the lifters, I’d assume they have at least .100” travel , so anything from .040”-.075” should work good. If they are short travel lifters, usually need to be at the .035-.045” range.

[@raho24781]

@@highperformancecult ok Awesome they came today,,,there I'll set um up and let ya know hopefully I'm on point and there gonna make sweet sweet Music 🎶 🎵 Thank you can't wait to write ya back

[@raho24781]

Hey I finally cought up to the shop truck that ya built, WoW 👌 when I seen you I recognized your voice and your Patience, also I knew you were bad Ass but I didn't know that you worked at Texas speed,,. As far as my LS1 Motor when I reached out,,,I when I bought them steel roller tip Rockers and was getting my pushrods lengths,Lengths, ended up with 7.225 and ran great until I Mushroomed a Lifter ,,,,so I got the Johnson Link Bars, and since I have the Heads off I ordered the 224 225 600 @112 ,plus a pair of the prc 225 Heads 62 combustion Chambers,,,,the motor got arp's all in and around and already was 11 to 1 ,I had a cam similar to that,,,you know I'd love to go bigger lol ,but it runs sooooo good on the street, and if I ever get I out to the track lie Laguna Secca type stuff it should track well,,,. So I liked and subscribed to your page,,,,I tip my hat to you ,you are Very Very Resourceful and enjoyed watching almost every episode of you building that truck,,looking forward to seeing more of your Videos,,,today alls I needed to is here your voice and Locked right in and ,You Are A Great Teacher 👍 👌, Thank you Soooo Much Appreciated an hope to see More Videos of your Awesome Work and Therory Knowledge and experience Thank you 🏁🔩🦍🔧🏁

[@highperformancecult]

That truck was a fun build, recently put the newer Gen 5 L8T 6.6L in it. I have another build coming up if we can find some shop space. A 1994 OBS with LS7 crate engine and 6L90. Will do the videos on here also. 😎 If you have Instagram follow Potak_at_HPCult and you’ll see more of my daily work projects also.

[@catfissh]

So with Johnson lifters we want about 1/2 a turn after lash to full seat the rocker right?

[@coltdevine994]

Did you torque the heads down to final spec and did you do anything to the lifters when installing them before measuring?

[@Simple_Youtube]

So from the video I'm looking for about 5 1/2 turns from zero lash to get the correct preload on an LS7 lifter which is .1000?? I keep reading. .0800 preload on an LS7 lifter. I have a BTR cam in an LS2 that came with 7.4 push rods and the valve train is loud. Like a clack loud. Thanks for the video

[@justinsmith6846]

I have a lq4 that installed a btr stg2 v2 cam in with stock replacement lifters stock heads and stock mls head gaskets. I used my stock pushrods and it some lifter/sewing machine type noise. I have a set of 7.425 push rods would those help quieten down my valve train noise?

[@highperformancecult]

Most LS engines have that sound, depending on the lobe design. Would need to measure your current lifter preload with both pushrods and see what it is first. Shoot for .080-.100”, or just past one full turn on the rocker bolt if you watch the video. Roller rockers are also an option for quieter valvetrain sound, but do very minimal gains (if any).

[@bowhite1293]

Pretty much the way I do it except for the junk timing chain tensioner. Trash it and run the LS2 timing chain dampener.

[@josephpotak]

That’s usually what happens. Leaf springs are for old cars and chariots.

[@offensivetomato2294]

For me it took me about only 1/2 turn and alittle more also it seems the lifters won't ride on the cam the whole time and will then drop onto the cam does that mean my pushrods are too short?

[@raho24781]

Hi I set all the 7.225 PR's in ,,,and set them all in mind you TS said on the box there .175 shorter zero lash at 7.2 so another 1/2 I was good with 3/4's of a turn,,,,,soak them set um all in and went thru the firing order 1.8 and so on ,,,,so most gave me 3/4's of a turn before it clicked off 25 ftlbs I think #6 exhaust valve gave me a full turn but when that happened I could feel the lifter squish some ,,,so I went thru them all again following the firing order and everyone clicked off at 25 ft lbs....the Heads were decked to .001 as well ,,,,this is where the 7.225 came in ,,,,,after I went through them again I clicked off the remote starter they all appear to be rising and falling evenly,,,, My First LS,,,,so what ya think,,,,,I'll button it up, fire it up and listen 🎶,,,,,if it all sounds good I'll let it run a few heat cycles then dump the oil and Filter tidey up and Test ride.....if ya think i need to tare it down and start from scratch,,,it would be no problem,,,,there's alot of money and time in this LS and it makes alota power, don't wanna hurt it at all

[@highperformancecult]

Sounds like about .055”-.060” preload. You should be good to go, even with unknown lifters. If you want to take it a step further, you can do a compression test to verify no valves are hung open. Probably not necessary, but sometimes helpful for a sanity check. Good job with the build!

[@raho24781]

Hi Thankyou. I set everything up on the 24th went back in the house after I Torqued the last ones 3 of them were off ;( then I remembered that I didn't check placement flat side up 0oops,,,so the next morning sure enough, and thats why I got a whole turn more on 3. 7..and 4.so 8 fliped them around going back through the firing order,,,and buttoned up the rest and Fired up,,,,right away i could here a smoother Motor and since I have Fast Smart injection it's back in learning Mode,,,,different rocker ratio so small bump to lift and duration,,,,smoother and driving not hard at all yet it blips over 6000rpm like Butter,,,,so I'm very very happy,,,Motor is Fresh Machined 11 to 1 Forged Probbes H beams and all ,,put a fresh set of TR55's and a friend ordered me some Liquid Molly 5 40 synthetic,,,,is that good oil here in.California ? What oil's is the best for a Pumped up LS Motor ? And Oil filter i.seen the posts about the AC Delco oil filters so ill try and find me a K&N tomorrow unless you have a brand you use then I'll get the same. Thank you BiG Time ya put a lil extra Confidence in me ,soooo Apreciated