LS Engine Tech: Measuring for Proper Push Rod Length

Comp Cams Push Rod Length Checker
amzn.to/2Bsx1zV
ARP Head Bolts (pre-04 - with the 2 shorter outer bolts) 134-3609
amzn.to/2iOI6QI
Here's how to measure for proper push rod length on a new build where you're changed anything in the valve train, such as cam, rockers, decked heads, etc.

[@TexasGTO]

Finally. A video that easily explains this to someone that has never done it. Thank you.

[@ScrufsGarage]

Thanks for the kind words. Very glad you found it helpful. I actually recorded it multiple times trying to keep it simple and clear.

[@TexasGTO]

Scruf's Garage and you succeeded

[@TexasGTO]

Scruf's Garage Also, I had those heads too. Putting blower on my car now

[@ScrufsGarage]

Ohh, nice! What compression ratio did you go with?

[@TexasGTO]

Scruf's Garage For NA I was almost 11:1 for lsa I'm 10.5:1

[@Bigtoe7272]

Simplest explanation of how to use this tool. Great job!

[@mathewshackelford8037]

Great video. One thing I think worth mentioning is when the valley cover is off, you can confirm the lifter is on the base circle by looking at the camshaft. At least when I used the #1 cylinder for my measurements, I could see both lobes/lifters.

[@stepheno.2730]

Your videos have been extremely helpful assembling my first LS engine. Thank you.

[@gary-powdercoatingspeciali3093]

Finishing an engine my brother started for me and now it's up to me to figure out the rest being that he passed.

[@ScrufsGarage]

I'm so sorry to hear that your brother passed. That's a tough lose. My sister passed in March from cancer, so sadly I understand the feeling. Best of luck on the engine build, and if you have any questions, post them up and we'll get them answered for you.

[@sergeantscumbag2116]

dont ever sell that engine just keep it forever it will always be a good memory of him

[@gapu263]

Thank you for taking the time to put this video together. Very straight forward and easy to follow!

[@ScrufsGarage]

Happy to share! And thanks for watching!

[@ThunderAppeal]

Yes, for an idiot like you who cant be bothered to figure out how to properly check for push rod length it is 'easy to follow'

[@steveaycock4853]

Man your videos are great, but I followed your process on pushrod length and determined stock length was ok. When I done the final assembly with new .051 gaskets (same as what was stock) and torqued with new studs, I came up with about .005 preload. I had to switch to a .025 longer pushrod to get nominal .030 preload. I'm running comp short travel lifters (.020-.040) preload. Just wanted to tell everyone you have to be pretty precise with these lifters as stock lifters have way more tolerance. Keep the great videos coming.

[@blksheep83]

Thanks for your video, I was confused by some other methods but watching your video it was very straight forward.

[@ScrufsGarage]

Awesome! Glad it was helpful. Good luck on your project!

[@454Chuy]

After watching so many videos and still confused by them this is the best one

[@ScrufsGarage]

Awesome, glad you found it helpful. Thanks for watching and good luck on your project!

[@454Chuy]

Scruf's Garage one more question, after you get the right pushrods, you still torque them down to the 22 lb ft correct?

[@ScrufsGarage]

Yes, the torque spec for the rocker arm is 22 ft/lbs. The "Cylinder Head Install - Part 2" video leads off with installing the push rods and rockers arms and has some installation tips that may be helpful. Check it out if you haven't already. kzbin.info/www/bejne/maGvqIqajLCpea8

[@454Chuy]

Scruf's Garage awesome I just did, great videos! They help a lot! Keep up the good work!

[@ScrufsGarage]

Will do! Thanks again for watching!

[@jeffscott3160]

Excellent tutorial! Every step well explained! I think you pre-load numbers are a bit much though. Most cam manufacturers, as well as OEM recommend .050 lifter pre-load. Always go by your manufactures specs of course though 👍

[@steveaycock4853]

Your videos are great, a big help for ls newbies.

[@ScrufsGarage]

Always happy to help! Thanks for watching.

[@myxa6626]

First video I’ve found that really helped me understand this process Thankyou so much

[@waynecotner3331]

Lol everything is a lifter to this guy

[@WhiteBuffalo187]

🤣

[@fernandoescobar5236]

great video. As I chase my tail after the rebuild I never noticed or took this into consideration. Now the Smog Check is way past due and I need to find the source of my dreaded P0300. I'm sure a tune will need to be done regardless since I installed a Stage 2 Cam and I keep getting misfires at idle according to the obd2 scanners.

[@miguel300ish]

Fernando Escobar almost every cam sets off the misfire at idle , I have a mild cam on mine an same thing got fixed after the tune

[@micthegreasemonkey2918]

anyway all my problens aside. i liked your smooth delivery in videos very precise & 2 the point.

[@ScrufsGarage]

No worries. I'm glad the video was helpful. Good luck on your engine build!

[@JKZ103]

Great stuff man. Putting mine together now.

[@ScrufsGarage]

Awesome, good luck on your build! Thanks for watching.

[@brkfd8143]

Awesome videos! Very helpful, thank you!

[@ScrufsGarage]

Brk FD thanks so much, glad to hear the video was helpful!

[@moe4772]

One of the best videos for this 🙂 Thanks! Liked!

[@ScrufsGarage]

Glad it was helpful. Thanks for watching!

[@kirkwest6654]

Any body help me find videos to do my first build on getting valve geometry right? Gonna try to get roller lifters/rockers on SB 350

[@aintright3889]

Right on, its a bit lengthy but he's really thorough, just a question on pre-load, should it be .070 or half the total travel of the lifter minus 50% which might be .080? Just my 2 cents worth.

[@MrSmokin04]

You could always mark your PR checker bro. It will make your rotations easier to count.

[@J.PROJECTZ]

Best explained video out of 10 I’ve watched 😅

[@ScrufsGarage]

Thanks! Happy to hear the video was helpful. thanks for watching

[@J.PROJECTZ]

@@ScrufsGarage time to build my 5.3

[@roguecanine157]

Awesome job!!

[@donrutter6765]

LS has hydraulic lifters, they arent as critical as a solid roller. Old sb chevys had a zero lash then you went 1/2 turn to a 3/4 turn further. Thats your wiggle room for pushrod legnth, the 1/4 turn thousandths of 1 full revolution of a sb chevy rocker bolt. Stock chevys came with 3/8 fine rocker bolts, so you need to look up how many TPI (threads per inch) of that bolt. Divide the number of threads -- example : if you have 10 threads per inch, that means you have .100 for every turn of the rocker. This is a random TPI I used so dont use it, research it. So if you had .100 per turn, 1/4 of .100 is your margin of error which in this equation would be .25.

[@steveaycock4853]

I think the rocker bolts on a ls is m8x1.25. Doing the math 1.25 ÷ 25.4 (inch conversion)= .049 per turn.

[@jaylestingi5418]

Steve Aycock Rocker/Trunnion bolts on LS motors are not adjustable! Totally different than a traditional small block. The rocker bolts are torqued to 22 ft-lbs and that is the end of it. Adjustment is done solely through the length of the pushrod.

[@steveaycock4853]

@@jaylestingi5418 only if you are running stock deck thickness heads, gaskets etc. Short travel lifters only have .020 TOTAL preload. Even with all stock components it's possible (as in my case) you may have to run a longer or shorter pushrod to get correct preload.

[@andyh3446]

Great video! Thank you! I am doing a little n/a build on my T/A over here in Germany. I am looking for a good adjustable pushrod tool. I am running with stock rockers with upgraded trunions and dual beehive springs. I believe the car has ls7 lifters. The heads are 243s and will be replacing my stock 241s. The car has a mystery thunder racing cam from what the previous owner told me. I am lapping valves and replacing valve seals. I will be using stock .0051 composite gm gaskets. I want to do it right because I know the guy before me who swapped the cam didn't. What thickness pushrod do you recommend for an upgrade if I need to change them?

[@ScrufsGarage]

Your build sounds very similar to mind. I replaced my stock 241 heads with cnc ported 243's. As for the measuring tool, I used the Comp Cams version. (linked in the episode notes). They're basically all the same. The LS7 lifters are good (that's what I went with). Just be sure to inspect them if they've been in the car for a while. I too had an old Thunder Racing cam installed by the previous owner. Once you get it out, the end is typically etched with the cam #. Mine was a TR220 (220/220), which was a mild cam. I found a lot of cam lobe wear on mine however and that had affected the lifter rollers too. Inspect yours closely. Mine originally had the composite head gaskets but on final build I went with the GM MLS gaskets which are slightly better (and what a motor with 243 heads would have used). As for push rod thickness, I reused my Thunder Racing ones, which are .080". That will suffice the vast majority of builds. And depending on the age of the components, it might be the right time to do the oil pump and timing chain too.

[@andyh3446]

Great info, thanks!

[@johnnyfive3872]

I got the exact same measurements as you. However, mine is a stock LS2 with SS1 cam. The cam has a .050 smaller base circle than the stock cam which typically would mean I would need a 7.425 pushrod. However, the stock pushrod is actually 7.385 which like your measurements technically would mean I would need a 7.410. If I use a 7.425, I’m at .087 preload. I believe BTR recommends up to .100 preload. With a 7.4, I’m only at .062 preload. I see most run the 7.425 to quiet the valvetrain. I’m on the fence here. What’s your thoughts? How has your motor been running?

[@tfox1672]

Great video!

[@ScrufsGarage]

Thanks for watching! Glad you found it helpful.

[@marioalanis1855]

Good video man nicely explain

[@ScrufsGarage]

Mario Alanis awesome, very happy to hear the video was helpful. Thanks for watching!

[@2GUNMASTER]

Great video. Isn't the factory length push rod 7.42?? If so, you didn't need new ones did you?

[@ScrufsGarage]

2GUNMASTER that’s correct, the factory length is 7.400. I already had an upgraded set of .080” wall push rods so after checking them for straightness and cleaning, I decided to reuse them.

[@bigbilltoady412]

I'm at 7:48. I've never done this but I'm thinking instead of disassembling every thing I would check with feeler gauges the amount of clearance, disassemble and adjust the push rod what ever the feeler gauge shows and put it back in. Check again of course but it should be at zero lash. That way you don't have to go back and forth. Also. How about leaving the adjustable part of the push rod down by the lifter with the valley pan off? Better yet? That way there is no disassembly at all.

[@GTStuning-]

Good job on the video 👍👍

[@ScrufsGarage]

Thanks for watching!

[@dr.schmuck3845]

Hey man I was wondering, if I install a btr stage 3 camshaft in my 2010 Camaro ss manual, with the proper pushrods and valvesprings, would it be safe to drive a few miles to get my Camaro tuned?

[@ScrufsGarage]

It may not run perfectly, but you should be fine to drive to the dyno. But I wouldn't do any full throttle pulls until after tuning.

[@WhiteBuffalo187]

thanks for the video ! Very helpful !

[@ScrufsGarage]

Glad to hear the information was helpful. Thanks for watching!

[@JuanSanchez-ck6nm]

Great video, what kind of prc heads are you using? i have some 227 prc on an lq9... just wondering if the push rods would be same size or close to yours?

[@cbr1thou]

Im using johnson short travel lsr2116 i believe is what they are, .035 preload +- .015, i plan on measuring the length of the pushrod checker with 8" calipers, as i am turning only .038 or so preload target. Why cant i just measure overall length of checker?????

[@jronayne88]

awesome video

[@ScrufsGarage]

Thanks for watching! Glad it was helpful!

[@cbr1thou]

Great video, thanks, liked n subbed

[@ScrufsGarage]

cbr1thou thanks for watching. Very happy to hear the video was helpful!

[@vb5457]

I am this push rod I am setting up to install, your help would be appreciated

[@michaelcullen6398]

Ok Excellent video! My question is can i follow the same steps that you have laid out without dissembling my old stock roller lifters? Basically i was under the impression i could measure my pushrods during final assembly and have already torqued my heads down on my 408 inch Lq9. So taking my measurements following your instructions (only with my stock replacement comp cams roller lifters instead of your solid lifters) will that change the lifter preload that you've provided at .070? After the smoke cleared my math came out to a 7.3325 push rod. Thanks for the post much appreciated!

[@ScrufsGarage]

The challenge with not using solid lifters is that you can compress the lifter or it can bleed down (or wasn't fully pumped up since the motor hasn't run) and give you a false reading.

[@michaelcullen6398]

Ahh i see... well so far I've checked 3 separate valves and have had the exact same reading on all three. I guess i will have to cross my fingers on this one. Thanks again.@@ScrufsGarage

[@ScrufsGarage]

No problem. Best of luck. Let me know how it turns out. Hopefully a super quiet valvetrain!!

[@dangerousfreedom4965]

Michael Cullen what are the cam specs?

[@raszamataz46]

great video helps alot thanxs..

[@ScrufsGarage]

Thanks for watching! Glad the videos are helpful.

[@josehuerta7856]

if i am milling 243 heads .20 what pushrod size will i need?

[@yolofullsend]

Could you just measure the screw area with calipers and add it to the 6.8?

[@brappplife9879]

Very helpful thanks

[@micthegreasemonkey2918]

yes i did unfortunatly & i know the card is correct comp cams hav a similar cam with similar specs.

[@micthegreasemonkey2918]

yeah scruff im getting the right numbers but im getting intake for exh and visa versa.

[@trentkammerer8639]

Awesome video! Curious, why did you not torque the rocker bolts before measureing?

[@ScrufsGarage]

Trent Kammerer For this check you only need to get the rocker snug in the rail so there’s no play. Also, the push rod checker tool isn’t designed to have a load on it. If your tool length was too long, then as you torque down the rocker, you would be slightly compressing the valve spring, which puts a load on the checker tool.

[@trentkammerer8639]

@@ScrufsGarage Makes since. I guess I was thinking about starting with it small enough the first time to ensure I didn't torque down onto the valve spring. I also plan on using something like this to do the test. www.summitracing.com/parts/cca-4758-2/overview/. I guess what you are saying is the difference between snug and torqued on the rocker bolts is just a negligible couple thous?

[@ScrufsGarage]

Yes that's correct. Snug vs torqued down is a negligible difference. They don't offer push rods in that small of increments, so there's some margin of error.

[@Dooguy]

Late to the party here.....i bought a car abuot a year ago , put on less than 500 miles and had a roller rocker failure, someone didnt tork properly....im changing out the broken one now. Ive followed your other video about the trunion upgrade and i want to do this since i recieved the factory parts with the car. (not positive I have the stock pushrods tho) I do know that along with the rollers, i have texas speed push rods and a vr2 cam in the car. IF i went back to factory rockers, would i need to change pushrods too? or could i just bolt on the fact rockers and go.

[@00infernoGT]

is this measurment taken with lifters "pumped up" or fresh? would there be a difference between the two?

[@ScrufsGarage]

So I used an old lifter converted into a "solid" lifter. I did a video on how to do this that you can reference (free and easy). The "solid" lifter simulates a fully pumped up lifter, and prevents the lifter from collapsing (like could happen if you used a regular lifter). The solid lifter is only used for measuring the push rods. Don't run it in your engine.

[@donrutter6765]

You want the lifter all the way to the top, not compressed to get your measurement, and then your preload measurement is what the lifter manufacturer reccomends. This is similar to the old sb chevy zero lash and go 1/2 to 3/4 turn further method. But, you contact the lifter maanufacturer or research what your brand lifter reccomends.

[@micthegreasemonkey2918]

yeah scruf its a gm l67 s/c 3800 anyway ive got a diemma . i measured the cam lobes & subtracted the minor fm the major & got 8.5 intake & 9.0 exhaust now my cam card says valve lift inlet .564 × by r. ratio 1.6 = 9.0 & valve lift exhaust .534 × 1.6 = 8.5 does this mean my cam grind is wrong or these 2 figures dont mean the same thing ? just a coinsidance ?

[@ScrufsGarage]

When you measured the cam lobes, were you in metric or standard? If you were metric, then 8.5mm/25.4mm = 0.334" of lobe lift. 0.334" x 1.6" = 0.534" valve lift. Typically the cam is advertised for X amount of valve lift, based on a given rocker ratio. Is the cam card giving you valve lift or lobe lift? Valve lift = lobe lift x rocker ratio.

[@chrismackin7882]

I have a 1975 Ford f250 with a 360 I replace the top end new can new lifters pushrods timing chain. Got it all back together got it running and with 40 minutes of just run time heard a ticking noise took it all back apart and found out that my cam add eaten five of my lifters does anybody know what caused this cuz I'm completely puzzled since then I pulled the motor and had it completely gone through but I still don't know what caused the cam 2 destroy v lifters with only 40 minutes of run time if there's anybody out there with any ideas I would surely appreciate a comment below because at this point and I really don't want this process to repeat itself thanks

[@Vcoldduck]

would torqueing the rocker change the lenght or would it be to slight. I'm working on a 4.0 jeep and the rockers are set to torque.

[@moabman6803]

Very good video

[@ScrufsGarage]

Glad it was helpful. Thanks for watching!

[@levell300]

What I don’t understand is why you didn’t torque the rocker arm to spec when finding zero lash? I’ve never disassembled the rocker arm assembly before so I may be missing something obvious. Thanks for making the video.

[@ScrufsGarage]

You will need to snug it down so there's no movement, but getting it to the exact torque spec isn't necessary since you aren't going to run the engine. You'll find that the measurement different between getting the rocker arm bolt snug vs torqued is near zero.

[@MrChevroletEd]

So we aren't compressing the lifter are we? I didn't make a solid lifter like you did and my heads are torqued, so that is out of the question. I have my rocker to where it has a little side to side play, but no lash unless I pull hard and compress the lifter. Am I where I want to be, or do I need to go tighter?

[@ScrufsGarage]

No, you do not want to compress the lifter. Lifter pre-load is the spec you add to the measured length of the push rod checker. A solid lifter just prevents you from accidentally compressing the lifter. It sounds like you are were you want to be.

[@claytonhaske]

do i need to get the intake milled too, if getting the heads milled .020? if so, is there a way to figure out how much? tia.

[@ScrufsGarage]

Milling the heads will change the clearance on the intake, but you should be ok at that level. On the LS6 intake manifold I believe I had to do a little massaging on the bosses where the intake bolts go through the intake on the bottom side. Had to take the leading edge off. I don't recall needing to do that on the Dorman LS2 intake. (it's been a couple of years now, so my memory is getting fuzzy, haha).

[@micthegreasemonkey2918]

ok scruff ill giv it 2 u in imperial. i measured & got 334" intake lobe & 354" exh now if i multiply intake valve lift by 1.6 rocker=534 & valve exh lift × 1.6=564 the exact opposite to the cam card. card says intake .564 & exh .534 is it right scruff.

[@ScrufsGarage]

Are you sure you identified the intake lobe vs exhaust lobe correctly on the cam? If you still have concerns, I'd call the cam company on Monday and run it by them.

[@uuhhhhhhhh189]

If you buy a cam kit that includes cam, lifters and pushrods all as a kit, do you still have to check push rod length even though the kit comes with rods?

[@ScrufsGarage]

In theory, if the motor is stock and the heads have never been off, then the cam company should know the base circle for the cam lobes and be able to include the correct pushrods. It's always a good idea to check, especially since you're taking the heads off any ways to change the lifters. But mostly likely you'll be fine.

[@uuhhhhhhhh189]

@@ScrufsGarage thanks for the answer. Would you have to check each valve or just one exhaust and one intake?

[@ScrufsGarage]

One intake and one exhaust should be fine. You could also do the same on the other cylinder head too if you were really feeling adventurous, but probably not necessary.

[@uuhhhhhhhh189]

@@ScrufsGarage thank you very much

[@RollTide3ROll]

good video

[@tonybustos2396]

Very informative gracias😜

[@ScrufsGarage]

Glad the video was helpful. Thanks for watching!

[@julianfaudoa5709]

You partially bolted the head on because you knew you already had compressed head gaskets right?

[@ScrufsGarage]

That's correct. I used the old head gaskets which were already compressed for measuring. At that point, you only need to get the head bolts tight to take out any play, but the torque sequence isn't needed since you aren't compressing new head gaskets.

[@joshuawhitelaw9702]

Are those heads PRC Castings or ported O.E.Castings ? are they from TSP ?

[@ScrufsGarage]

The heads are from PRC/TSP. They are CNC ported OE 243 heads (actually they're 799 heads, but 243/799 heads are essentially identical, especially once they're ported)

[@joshuawhitelaw9702]

I just sent my 317 castings out Monday to TSP, did you go the stage 1 or 2.5 ? I'm putting together a TSP Forged 408 single turbo motor together for my 1996 Trans am. I'm seeing we selected a lot of the same parts for our builds.

[@ScrufsGarage]

That sounds like a beast of a build! I went with the stage 1 porting. Looking at the flow #s, the 2.5 porting didn't seem to add much. And my build was already getting wildly expensive, haha. But the heads are beautiful. They really seem to do a good job. Once I get it dyno'd I'll post the results.

[@joshuawhitelaw9702]

what cam are you running, and what are your power goals ?

[@ScrufsGarage]

Joshua Whitelaw I went with the Cam Motion Titan 4. The ramp rates on their cams are easier on the valve train and give me some good torque out of the corners and decent street manners. I should be around 11:1 compression. So I'm guessing 420-430 rwhp. More would be gravy but with a 5.7 and that cam I doubt it will make much more. But my goal is reliability, torque, and street manners.

[@fasnuf]

So how do I do this with stock hydraulic lifters with stock heads that have never been removed? I mean, doesn't the hydraulic. lifter deflate/inflate changing length? I'm confused.

[@ScrufsGarage]

Correct, the lifters will lose their prime after they sit for a while, and you may not get accurate measurements. Thus the need to build a solid lifter for use during the measuring process (I have a video on how to do that) Of course that means pulling the heads off but depending on the mileage of the motor, it's a good idea to install new lifters.

[@fasnuf]

@@ScrufsGarage Ok. so how exactly does building a solid lifter work? I mean you have to take into account the preload on the lifter, roller on the tip length and its overall length right? I have no desire to remove my heads and I'm sure most people don't just to do a cam swap. I figure once I pull the cam until I'm ready to measure will be only a couple hours.

[@ScrufsGarage]

You can build a solid lifter by modifying one of your old stock lifters. kzbin.info/www/bejne/Zl7Hp594nrJ5i5Y As outlined in the video, you are taking the measurement of the pushrod length that achieves zero lash, then add to that measurement the needed amount of preload. But again, this requires removing the heads. If you're only changing just the cam on a stock motor, then the cam supplier should be able to recommend the correct pushrod length based on the base circle of their camshaft.

[@jrobles1019]

Why do you recommend doing that lifter hack before checking for PR size if your not really torquing anything down to check for size??

[@ScrufsGarage]

It sets the lifter at a fixed size. Just prevents an erroneous measurement because a lifter was partially collapsed.

[@jamesbergman4917]

Why not use the pushrod checking springs that provide very little rate and wont collapse a lifter plunger? And why did you not mark the head of the valve and rotate the engine to check for sweep and location of contact?

[@0Gravity1966]

I'm working on my first LS motor, I've built many OS SB and BB chevys in the past, so Im at the research stage, and ripping down my junkyard 6.0 LQ9. Regarding this video, what would be the procedure if you didn't have the old gaskets? Do you wait until after you install and torque the heads down to do the measure, or can you dry fit the head without a gaaket and then deduct the amount that a compressed head gasket specs say it wil be?

[@ScrufsGarage]

Yes, you could dry fit and then add the amount of the compressed head gasket spec.

[@singdams]

What is the best alternative for me. I live in Hawaii and there is no tune shop. Going to get headers, cams done.

[@ScrufsGarage]

With your planned mods, you'll definitely have to have the car retuned. If there aren't any dyno tuners available, then you'll have to find a shop that can do a mail-order tune for those specific mods.

[@singdams]

@@ScrufsGarage I figured that would be the case but not wanting to go that route. I have seen not herd horrible things with mail order tunes.

[@scottydoesntknow254]

What was your cam size and how much are your heads milled

[@ScrufsGarage]

The cam is the Titan 4 from Cam Motion. 227/232 - .612/.595 lift - 113+4 LSA. The heads were milled to 60cc chambers, which I believe was around .010". The heads are PRC stag 1 243/799 heads and they did the machining and setup the valve springs before delivery.

[@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

[@solangus7730]

What the hell,I was getting my heads done already have huge cam and so far using stock push rods n bloke at shop said I'd only need lifters head bolts n gaskets when I get my heads back,taking 30tho off hopefully,but if U think about it half a turn is 50 tho so really what's 30tho off ,but least now I know how to check ,my mate put wrong size push rods in his 351 with alloy heads should of heard the tapping😆

[@leomorrell3261]

So if my pushrods are the same size as yours 7.4 would that mean the math u did would work for mine as well?

[@ScrufsGarage]

It would be best to take the measurements from the engine you are building and then do the math to make sure the 7.400 push rods are what you need.

[@coarsegrind]

If you want .070 preload why don’t you add a .070 shim under the rocker guide? Then you’ll have the exact length of pushrod that you need.

[@dr.schmuck3845]

This is probably a stupid question, but I want to be sure, which valvespring is the intake and which is the exhaust? Thanks in advance

[@ScrufsGarage]

Not a stupid question, and an easy mistake to make. To me the easiest visual check is to see which valve spring lines up over the exhaust port and which one lines up with the intake port.

[@dr.schmuck3845]

@@ScrufsGarage so the valve spring above the exhaust port is the exhaust valve and vice versa?

[@ScrufsGarage]

Yes that's correct.

[@dr.schmuck3845]

@@ScrufsGarage thanks man, I plan on installing a cam in my Camaro this summer!

[@mhaab1]

Scruff are you screwing the bolt all the way down till it stops when you do your check?

[@rahrah8076]

Those are Rocker arms not lifters my friend

[@MaxTune]

Good vid, but you called the rocker and pushrods lifters a few times, which might confuse a newb.

[@Faisal-ro1zr]

thanks bud

[@ScrufsGarage]

Glad the video was helpful. Thanks for watching.

[@micthegreasemonkey2918]

hi scruf ive got a new cam to go in & they gav me 2 different size rods i hav measured the cam lobes & got 5 mm difference on each lobe so the longest pushrod will go to the smallest lobe correct.

[@ScrufsGarage]

What kind of motor? Typically, pushrod length is measured from the base circle of the cam lobe (not the lift portion). That's why we took the measurements with the valve closed. All things being equal, if the base circle is the same, and the rocker arm length is the same, then having a pushrod that's too long would keep the valve from fully closing (or damage the lifter). Obviously your specific application may be different, so my recommendation is to talk to the cam company and make sure you understand which pushrods go where, and why they are different length.

[@Teddybites]

Would they all be the same length?

[@ScrufsGarage]

In most applications they should be. The base circle for the cam lobes should be the same and the deck height of the heads should be the same. But you should at least check both an intake valve and an exhaust valve to make sure nothing funky is going on.

[@jasonrogers143]

So where is the end of your rocker on your valve stem? Also I want to know how many days did it last before it blew up.

[@ScrufsGarage]

I'm not clear on what you are trying to ask. The LS engine family uses net lash rockers, so the only way to adjust the sweep of the rocker tip is to shim the rockers or pedestals. However, there is no seat under a stock rocker arm that can be adjusted on a stock setup. The entire stand has individual pedestals on them that align the rocker and provide the proper seat height for them. The stand and the pedestal are one piece. No adjustment there. You can shim the stands, but you would not have that option on an all stock engine, nor should it need it.

[@zacatecano1986]

My question is . Can the tool withstand the spring pressure ?

[@ScrufsGarage]

Note that in this method, the measuring tool is not subjected to spring pressure. You're just adjusting it to zero lash.

[@zacatecano1986]

@@ScrufsGarage i understand now thanks for the very informative video . Keep em coming

[@cbr1thou]

Just got off manton site, they say ball ball measure overall length, you say not to, so whos right?

[@ScrufsGarage]

It depends on how the measuring tool you are using is designed. I used the Comp Cams tool, so I used the process that Comp outlines, which is based on gauge length, not overall length. See "technique #1" at the bottom of this page... www.compcams.com/Pages/417/valve-train-geometry.aspx

[@eddiehill3545]

Try to find the video on making the lifter to measure your push rods

[@ScrufsGarage]

kzbin.info/www/bejne/Zl7Hp594nrJ5i5Y

[@hotrodj21]

you know there is a guy at sloppy mechanics channel that puts cams in his engines and uses the original push rods and makes over 1,000 hp turbocharged

[@ScrufsGarage]

I'm not familiar with his specific setups, but there are a few basic considerations. Depending on what components you've changed, you may need a different length PR (which is the point of this video). As for upgrading PR's, remember that dual valve springs have a lot more spring pressure than stock beehive springs... thus more force on the PR's. PR's don't make horsepower, but they can cost you HP... or an engine. Deflection in the PR will cost you total lift (and thus HP) and a risk of a failure. Is it worth the risk to save $100? As for reusing PR's, I chose to reuse my PR's but I already had an upgraded set of .080" wall PR's. But be sure to check them for straightness. Roll them across a flat pane of glass. If they wobble... toss them out. HTH

[@hotrodj21]

Scruf's Garage i can send you the links to the parts hes using. the valve springs he is using are single coil springs good for .600 lift for pac #1218 cam is an elgin cam .575 .575 lift every thing else he uses is directly original to the engine. with out the turbo it makes like 560 horse? with just a cam. latest engine he did this to was a 4.8l ls1 he even used a push rod that was egg shaped from riding on the cam lobe and just flipped it over and used the good side on the cam. he also dosnt torqe anything down usually. just runs the bolts down with an impact...

[@hotrodj21]

Scruf's Garage i am not arguing with you i believe you i am just amazed at what this guy does.

[@ScrufsGarage]

haha... all I can say is I'm jealous of folks that have that kind of luck. I can use the best parts with the most OCD attention to detail during installation... and still have stuff fly apart, haha. but if it works for him, then more power to him. The single coil springs certainly keep the spring pressure down, and .575 is relatively low lift, which helps too. There can be some many variances between applications, that it's impossible to have "hard" rules about things.

[@hotrodj21]

Scruf's Garage i hear you and understand completly

[@petejoseph8257]

Good concise instruction, without a lot of jibberish and hideous bad music in the soundtrack, couldn’t be more clear on the procedure.

[@adolfouresti7561]

what cam are you running?

[@ScrufsGarage]

I went with the Cam Motion Titan 4 camshaft.

[@charliecadaver666]

Take your lifter ( holds a rocker arm ) lmao! Lifter = ALL VALVETRAIN PARTS!

[@Guiohms.m50]

4:23 Rocker*

[@joeybash4338]

What size cam?

[@ScrufsGarage]

I went with a Cam Motion Titan 4. 227/232 113+4 .612"/.595

[@micthegreasemonkey2918]

mm scruff do u think the grind is wrong ?

[@ScrufsGarage]

It sounds like it is correct. But you need to know if the cam card is giving you valve lift or lobe lift. And in your calculation, you have to convert from metric to standard. (there are 25.4mm per inch). If you still have concerns about what you received, then I would suggest you call the cam manufacturer. They'll be able to walk you through every detail of the cam and make sure you got what you were expecting.

[@stephentringale5865]

The info is good ..but the choking up a Lugy every other moment..Get a drink of water!

[@DodgyBrothersEngineering]

The way you are checking to see if the valve is closed is all wrong.

[@onehot57]

That’s a rocker not a lifter my son!

[@pabloperez6331]

Good video but is not a lifter is a rocker arm.

[@bowsertownes]

You have good intentions but you do certain things that just aren't right. Using old gaskets and not what you will use, yes you have to waste brand new MLS gaskets to get proper crush, noticed head bolts missing? Ever use a set of calipers or dial indicator? Again good intentions but not sure I would follow your instructions

[@ScrufsGarage]

Head gaskets are designed to crush to a very precise thickness. So whether you use the old gasket, or crush a new gasket, the resulting thickness is the same. Since I was using an old pre-crushed gasket, there's no need to install all of the head bolts. For the purpose of this process, the head bolts are just needed to seat the head firmly to the gasket/block so that there isn't any movement. But you aren't trying to seal against cylinder pressure. If you decided to use a new set of head gaskets for this process, then yes you would need to install all of the head bolts and properly torque them to spec since you would be crushing the gasket. But at the end of the day, you still still get the same measurements.

[@bowsertownes]

@@ScrufsGarage You just have alot of misguided information about assembly and people are taking your advice which is not correct assembly measuring procedures. Stacked/ erroneous measurements add up. If you're not a professional don't try to educate. It just adds to the already growing supply of misguidance out there.

[@Jcarney87]

Why do people call 5 hundredths ‘50 thousandths’

[@ScrufsGarage]

While they would be the same measurement, thousandths implies an additional level of accuracy. (ie, that it was actually 0.050", and not 0.049" or 0.051") Though often it is just what someone gets accustomed to saying.

[@petejoseph8257]

Don’t do it this way, there’s room for error. Start with number one cylinder on absolute tdc then take your readings of base circle on both intake and exhaust.