Engine Tech: Valvetrain Geometry

[@JunkyardDigs]

I Have been trying to figure out the 90° reference for 4 hours, this video finally made me understand it and made it seem so easy! This was the only one I could find on the internet. Thank you so much 🤘🤘

[@Hippie9D]

Lol, here from your video. BIG thanks to the Straub guys

[@markwells5645]

Me2

[@jlh8296]

I talked to Scott over the phone about this process to determine pushrod length. I checked all the corner cylinders of my build and I can say that this process worked flawlessly as it delivered the most lift and least amount of rocker sweep across my valve stems, each and every time I checked and double checked. Great video! Thanks Scott.

[@Hungry_Hippie227]

Used this method. And got a perfect center sweep with my flat tappet hydraulic lifter. Thanks a bunch. Finally ordered my oushrods today because of thia video!

[@jgilbert4756]

Video is 10 years old and explained it better than many others I've watched. Imagine how many people this has helped! (307k views and counting at 10/18/24). About to determine length on my solid roller 393w. Thanks Straub!

[@AR_420]

THANK YOU FOR THIS VIDEO!!!😊 Very informative and helpful 👍. Can't make everyone happy. Just some miserable people out there. I got EXACTLY what i was searching for and understood the material exactly. This is not a 72 hour highly detailed engine build, instructional video. So obviously and naturally, some things are going to be assumed. It's a great video about a specific step. No one is perfect. I appreciate the time you took to make this great video. Helped me tremendously in my journey!! My project and i thank you sir. 😊🙏

[@nikkigordon941]

yes sir this is a very good video probably the best on here .thank you

[@LandandSeallc]

Finally a video that actually explains how to do this correctly. Appreciate you taking the time to share it.

[@arturozarate1752]

kzbin.info/www/bejne/npS1hYKBo5WmoKcsi=qM5Q1d1179hVq1o5

[@arturozarate1752]

This a better way to check.....takes more tools though.

[@giftdcam8472]

I’m literally just down to determining the pushrod length for my TT 383 build and someone on a different video told me about this one and man am I glad I watched it because it made the process so much easier

[@donaldcoulter6017]

Thank you for an excellent video and explanation. I watched a half dozen tonight, and this was the clearest and easiest to understand. Thanks!

[@codystelzer5700]

Looks like I got lucky, this is my 2nd and extremely clear compared to the last vid.

[@speed150mph]

Cody Stelzer this was my first. I don’t think I need to watch any others. Oh look, how to degree a cam in the related videos.... I’m off

[@351nang]

Scott, hands down this is the best explanation/demonstration about. Thank you.

[@dezertdrifter]

So I spoke with Scott on the phone and he took the time to explain to me in more depth the problem I was having with this method. Basically I was off a bit measuring my 90 degree angle. You have to understand the importance of being precise as possible on this step cause the slightest miscalculation is magnified because of the angles and ratios. Once I got it right the pattern on the valve was very narrow and just barely off center, which tells me my valve is being pushed straight down with very little sweep from side to side. This is the correct way to set up valve train.

[@markwanc1103]

This is absolutely THE BEST description of how to find your proper push rod length.

[@forrestmiller4055]

For those of you that are being sidetract about the rocker ratio and thinking the ratio affects how many turns of the adjusting nut....this doesn't matter.The rocker ratio could be 1.2:1 or 1.9:1........ you still want to have the centreline of the trunions at 90 degrees to the valve at mid lift.....and then when that is established, measure for pushrod length.

[@speed150mph]

Forrest Miller to be fair, the rocker ratio does affect how many turns you need to turn the adjuster, it’s just that it’s already been included. He is making his calculations based on 1/2 of total VALVE lift, which is your cam lift multiplied by rocker ratio.

[@soerenchristensen4774]

This does not take the ratio into consideration. The lift is on the cam which will be multiplied with the ratio to create the valve movement

[@ChevyConQueso]

I was reading "Rocker Geometry" by Jim Miller from Engine Professional, Apr.-Jun. 2010 issue, and trying to wrap my head around it. It's not the easiest article to understand the first time around, and after a couple read overs I looked to see if anyone had done a video on it. This one here made it click right away, and makes it easy. For anyone who watches this, I suggest checking that article out for some more background on why this method works, why measuring "swipe pattern" is tedious, and no way to measure for proper pushrod length, and why a good narrow swipe pattern is simply a by product of using the mid-lift geometry method. Thank you Scott for the easy to understand demonstration.

[@JoshuaDoll]

Valvetrain Geometry is something most other engine building videos glaze over; this is by far the best video I've seen on how to properly do this.

[@nortonsspeedworld8771]

awfsh

[@benjaminheinzeroth6427]

Could you please make a similar video using shaft mounted roller rockers - showing shimming under pedestal mounts etc. for centerlines?

[@davidcollis4758]

This is by far the best explanation of measuring proper pushrod length and rocker arm geometry. Thank You for this video.

[@chuck3376]

Would just like to say big Thank you for your Talent. At 7:30 in the video your comment, You just established proper pushrod geometry. I then marked the top of my valve stem with a marker and held my rocker up and moved it back and forth over the valve stem. You now can actually see exactly where the rocker roller is located at half lift. Thanks again Scott for the video.

[@italian1488]

Great video, I’ve been racking my brain trying to figure out pushrod length without swapping springs or using solid lifters like almost every other video says you have to do. Thank you.

[@brianmiller4466]

Awesome vid! And Id like to take a moment to add you’re hands down the most helpful fella Ive run across. Ive never seen anyone say throw out call me if you need help/have questions as you. Hats off to you sir. 👍🏻👍🏻👊🏻

[@remylebeau9344]

I've watched a variety of videos read a lot about setting this up. Everything was all guess work. You're the first to introduce math and when dealing with precision measurements, you can't guess, you must measure. But... HOW? Well you clearly cleared that up. I've been stressing for days about doing this and if I'd get it right. Tons of second guessing and re-watching yours and other videos but your's is the only one that made the most sense. Sure enough, I did everything you said and with the first turns of the cam, I am 100% in spec with the rocker roller on the top of the cam. I'd like to offer you a virtual hug cuz you're amazing :)

[@apachebill]

I’m dyslexic AH. The whole geometry and pushrod length calculations voodoo have always been scary to me. This! I understand. This I can do and repeat over and over and check it and feel good about it. This gives us dyslexics a simple “visual” way to see it, understand it and accomplish it without the hoping and praying it correct and that we haven’t made a mistake. Thank you sir. Wish I’d seen this years ago!

[@EvilSSP]

Man I cannot thank you guys enough for this video. This is the absolute best I have ever seen this process explained and it made measuring my pushrods so much easier. I can't like a video harder. :D

[@davidtaylor9283]

Great video! Thanks for the excellent explanation. I spent a full day of my life trying to figure out push rod length for my 498 stroker BBC. I used 3 different measurement techniques and got consistently different length estimates. Your technique resulted in the longest measurements by about 0.10 - 0.15 over the other methods I used. I decided to rely on your method rather than collapsing lifters, looking at marker patterns, etc. Hope it works properly for me!

[@donrutter6765]

His method works on Crane roller rockers, but my roller rockers have a bigger wheel roller on the valve end, so the straight line theory doesnt work for me.

[@brianmiller4466]

Ummm? Just because the roller at the valve tip is larger, or smaller for that fact, doesn’t change where the center is. You go from center of the trunnion bearing to the center of the tip roller to determine your “center line”. Only hitch I can imagine would be if the intake and exhaust had different size rollers at the tip. And even in that particular case you would just have to measure/setup the intake and exhaust independently.

[@maroonmonte74]

Awesome video indeed! But just to see if I get this right, at the point of extending the adjustable pushrod (9:48) and taking up all the slack, the valve is still in it's fully closed position. So, at this point the lifter was sitting on the base circle of the cam, right?

[@kenstinnette6974]

Is it setting on the base circle of the cam

[@AlwaysConquer77]

CAM MUST BE ON BASE CIRCLE FIRST

[@1320horse]

Best video I have seen yet on how to properly set up rocker geometry. I just watched a different video that was like you said, full of misinformation. Thank you for teaching proper techniques. Awesome video!

[@billconserva1461]

This is the very best info to make the adjustments and push rod length selection I have ever seen!

[@bradleylovej]

This is the best video. Very nice explanation, and the camera got in there up close when it needed to

[@ronaldlewis6062]

Thanks for sharing I was taking notes as you are teaching because I will be performing this method this weekend on my 468 BBC Hyd Roller Cam . I commend Howard Cams wouldn’t sell me push rods when I ordered the cam now I know the reason. More performance and longer life!!!!

[@ashqelon7267]

Here it is I was pondering how to figure it out, knew the info was somewhere, It’s HERE!! Now I can do my Pontiac heads like this with an entire different set up and get the correct PR pieces .. Thank you Very much for this valuable wisdom teaching!!

[@stevelangworthy9553]

When measuring the pushrod checking tool, do you need to make any compensations for hydraulic lifters? This is a great video. Best on the net. Thanks!

[@rangeraficionado87]

My understanding is that if you're using lightweight checker springs, it won't compress the hydraulic lifter but you have to verify that visually.

[@superfuntime3107]

1:45 note. 90 degrees to the valve at mid lift.

[@19jody72]

Good reminder!

[@VGHCX]

Thanks for the detailed explanation. Nearly every other video on this topic leaves out the specifics.

[@SmokedTirez]

I know this vid is like 7 yrs old and contains stellar info I was wondering why no-one has done a video when it comes to shaft mounted roller rockers as setting the pushrod length is quite a different process..I know you said its ok to call I still believe in being courteous and let you ultilize your time in the manner you need to utilize it in instead of me calling at an inopportune time.

[@richardtice4560]

Excellent video! Makes logical sense. I tried this on my 454 with Edelbrock Performer heads and Harland Sharp rockers and encountered a problem-in order to get the line drawn at rocker pivot centers 90 degrees to the valve stem, the stud will be too short to catch any threads with the locknut. What to do now? Thanks

[@richardtice4560]

+Scott Foxwell OK, cleared that hurdle, thanks for the tip, but now I get a much shorter result using the marker method (12 turns out on the checker tool) vs. this method (20 turns out). With this method, the roller tip is to the exhaust edge of the valve stem, nowhere near centered. What am I doing wrong? Thanks

[@chevyracer71]

Scott Foxwell You’d like the adjuster to have 6-7 turns before it meets rocker trunion?

[@charlesmares4143]

This video was amazing! Explains and shows everything so clearly! Thanks!

[@Westcoastpedalboard]

Should edit the video to add a note about stock rocker studs sometimes needing to be swapped out for longer to get this method to work. I’m in the middle of trying to figure this out now. Thanks for the vid!

[@bucobuco7226]

This is what a video should be, I clicked he told me what he was meant to....I didn't hear about his wife, weather, or saw wrist and tired....made my day, Thank you.

[@kylelove927]

This tutorial just changed the game for me. Very good information!

[@stonesofetown6767]

Your video is great and easy to follow. I have a question regarding preload and how to set it. Using your method shown I can find the pushrod length. Then add compressed head gasket thickness to the length. And then add 50 thou for preload? Is the theory that the extra 50 thou simply pushes the lifter in 50? If that’s the case then how do you tighten down the adjusters? Do you use the same technique and rotations and the last 50 thou just automatically pushes the lifter down? I understand the pedestal type set up and shims vs torque but I’m unclear on stud type

[@straubtechnologies]

Yes once you have established the length you need, add .050" to the length for preload. Keep in mind all OEM and most aftermarket hyd lifters have .140" of plunger travel.

[@davelevison7252]

Hi, I kind of have a confusion about how rocker arm geometry is met when you have a larger cam, because if an aftermarket cam was installed with a larger amount of lift then the stock one, wouldn’t the larger lift cause the rocker arm to be out of spec with 90 degrees at mid lift. And if the push rods were changed to gain 90 degree geometry at mid lift with this new cam wouldn’t you lose the effect of the larger lift. My next question is how do you find correct rocker arm geometry with stock rocker arms, to my knowledge all you can do is just color in the valve tip and then rotate the motor over a few times and keep adjusting the push rod until the mark left on the valve is centered- is this the best way to this with stock rockers? Then how do you find the proper lifter preload, I am working on a 1979 302 Ford and I have been told to give each rocker arm nut a half a turn to set the preload after running the motor at idle loosening each rocker nut until the rocker arm clatters, then tightening the nut just until it quits clattering. When it comes to lifter preload wouldn’t this also change the rocker arm geometry.

[@chickenfoundation9323]

I’m using a Howard’s cams lifter and they recommend 1/2 to 3/4 turn for preload so if I were to go 3/4 turn with a 3/8 stud would that mean preload is .0315?

[@slapnutzracing2152]

I am building a 540 bbc with dart pro 1s. The question I have is to get proper rocker geometry do u need to torque the head down with the gasket? I also need to check my piston to valve clearance. I would hate crush a brand new gasket in order to set the geometry right. What I am really saying I want the proper pushrod for when I check my piston to valve clearance. Any advice would be greatly appreciated. Thanks

[@GroovesAndLands]

Question: What is more important - the 90* relationship between rocker and valvestem @ 1/2 lift - OR - a centered swipe of the rocker on the tip of the valvestem? I'm setting up a garden variety healthy 355 sbc. Using 1.6 roller rockers and Flotek 180cc heads. I used this technique to determine PR length. However, with this "correct" length PR, my contact patch between rocker tip and valvestem tip is a bit outboard of the valve centerline. I could "correct" that by shortening the pushrod - but then I wouldn't have the 90* angle anymore. Is one more important than the other?

[@danrittenhouse4288]

Scott, I read through all the comments and appreciate all the advice you willingly give. I had another question. I may be confused on where a hydraulic lifter sits when pumped up and in a running engine. I think I understand all the measurements and rationale however, here is the question. If I set up the geometry as you say, how is the lifter collapsing due to the 3/4 to 1 turn of the rocker arm nut and the resulting lifter collapsing and or where the push rod seat/lifter top cup (where the push rod sits) affect the measurement that we are calculating. In other words, it seems that the collapsing of the hydraulic lifter (versus solid lifter) would change our measurement (and the 90 degrees and so forth). Thanks in advance for your reply.

[@Saleen85111]

DAn did you ever figure this out? I assume your asking if you add the preload into the lenght of the push rod?

[@Milner62]

Finally got to try the half lift method and have to say I dont know what it is but it gave me a length that put the roller tip on the outboard side of the valve tip center line. Something is not right and I did this measurement multiple times and still keep coming up with a pushrod length of 6.50" length. If I use the OE pushrod length of 6.25" the roller tip is on the inboard side of the valve tip center line. Using 6.35" puts the roller tip slightly closer to the center line of the valve tip. Even adding the thickness of the head gasket would still put it at 6.40".

[@straubtechnologies]

With the length you must have a SBF. Rocker geometry from different mfg vary. You will need backset rocker. If not used a wide centered sweep pattern will wear out valve guides.

[@Milner62]

@@straubtechnologies, yep ford 302 OE roller. I did the math on the 2/3 lift method which in all my reading the other day kept coming up in posts after 2015. With the 2/3 lift method it actually gives me a 6.35" pushrod which puts the starting point just on the intake side of the center of the valve. Still doing some reading on the 2/3 lift method how ever and seeing if it would be a viable alternative for a street driven engine that wont turn over 6,000 rpm.

[@dezertdrifter]

I've tried this method several times and it leaves my roller tip way off center of the valve. The wear pattern is way outboard like the pushrod is too long.

[@phrogbubba8769]

Thank you, my friend! My first engine rebuild a success thanks to your video.

[@devildogae]

Where on the cam does the lifter need to be to have this work properly?

[@daneasley7602]

I am in no way an expert on this. As a matter of fact, I've never done it. But I would think that you want it on the low side of the lobe, "closed valve".

[@hotrodray6802]

Yes, he missed that completely.

[@snaproll94e]

If your mocking up the engine, it's best to use a used (previously compressed) head gasket. This will save wasting a new one to get the head in the location it will be on the finished engine.

[@brianjordan991]

do you do this with or without head gasket in place,excellent video

[@straubtechnologies]

With a head gasket in place. That gasket has a compressed thickness that will add to the total distance the pushrod must extend over in order to mate the lifter to the rocker arm.

[@cll375]

Great video! This is definitely going to help me out. I see it's and old video so I'm not sure if Scott still works there. From the video I could tell if the head gasket was in there. Once you get the measurement shown do you have to add to the measurement for head gasket and valve lash?

[@kissmyaskew9844]

Good question. I myself didn't notice if the head gasket was there or not, but curious if it needs to be accounted for. Seems like it would affect the final rod length.

[@earlanderson1676]

I have one question: Previously for piston to valve clearance checking purposes I converted two of the existing hydraulic lifters my engine uses into solid ones. I did this by using washers to locate the top internal moving part of the lifter (sorry not sure what it's called exactly) against the bottom of the retainer wire/clip piece. Should I use the lifters in this condition for the geometry check/set-up or change them back to original first?

[@philiparcamone7089]

I wish you could do a video on shafted rockers. This video was fantastic! I am trying to apply what you taught me to find proper shafted rocker arm alignment. Thank you

[@jedwebster8976]

Thank you. Just exactly what I needed to learn. Hope you do more instructionals. Very well done

[@coryholbrook4643]

Using this method I found out the pushrods I originally bought were dangerously short, .25” too short. Damn I’m glad I took the time to do this. I haven’t put too many miles on it yet so I hope the damage to the valve heads is minimal, it was good on the #1 exh valve I used to check this although my wear pattern was obvious, about 3/32” wide but centered over the top. So centering the roll pattern is obviously not the right way to determine PR length.

[@JCunningham21]

with hydraulic lifters you need to add the proper preload for the lifter used. Different manufacturers may require different preload for the same engine.

[@donrutter6765]

J Cunningham 1/2 turn on your rocker stud wont make a big difference. A 3/8 fine thread bolt has .042 per turn, a 7/16 bolt has .050 per turn. You buy custom pushrods at .050 intervals. Some builders like Ralph Johnson, Smokey Yunick etc. run their rockers on the outboard side of the valve, it turns a 1.5 rocker into a 1.65 rocker. kzbin.info/www/bejne/iJvEoKaOa5h3oa8

[@richwahneEXPERTSmadeEasy]

Wouldn't the head have to be placed on the block WITH the gasket to determine proper pushrod length?

[@hotrodray6802]

Obviously

[@jeffreydurham5342]

This is a very informative video on a widely misunderstood subject. The gasket whether or not it's there has no bearing on the information freely given. Unless you're getting custom pushrods or making your own you can't get them in increments smaller than your gasket thickness.

[@AR_420]

​@jeffreydurham5342, I 2nd that! Well said sir! Some people are absolutely ridiculous theses days. I was so happy last night when I found this video! Seriously, of we all could male that 1st comment positive, I think we'd all be working towards a better place. Not a declining one

[@tylerriddle4627]

Do I need to put in the check springs or am I good as long as I don’t pre soak the lifters and don’t compress them?

[@straubtechnologies]

You will need checking springs installed. Otherwise, there will be no way for the valve to actuate correctly as you rotate your engine.

[@jerrodwilliams6789]

@ 5:20 where you establish that initial 90 degrees I am unable to get my rocker arm high enough to establish the initial 90 because the stud is too short so i am unable to start the nut. What do i do in this scenario? Thanks for the video. I have a small block 350 with summit aluminum heads with comp Ultra-Gold 1.5r rocker arms.

[@straubtechnologies]

For Mock up you can use flat washers under the studs hex nut to get your measurements. More than likely you will need a 2" long rocker stud.

[@jerrodwilliams6789]

yep figured that ordered the 1.900 inch arp studs thanks for the FAST response!

[@trevman77]

So happy to have found this vid. This has been the most logical explanation of doing this. It all makes sense this way. Hands down. I can't wait to apply this. Thx.

[@deeeeeeps]

Excellent video! This is the proper way to measure, do NOT use the maker technique this is proper geometry and won't stress your parts. Thank you!

[@straubtechnologies]

David Sanders Thank you.

[@mareksumguy1887]

+David Sanders Why not use marker??. Marker technique seems much more fool proof than this!. The greater your rocker ratio... the more difficult (read: INACCURATE) this method gets.

[@straubtechnologies]

+Marek Sumguy A marker over math. I dont' think so. You base the lift off of what rocker ratio you are using.

[@deeeeeeps]

+Dave Mustaine Yes I left a warning comment on that video, haha.

[@dduplechian]

+Dave Mustaine I just watched it and was like WTF

[@Saleen85111]

If using hydraulic lifters.. do you add the amount of preload to the OAL length of the newly determined push rod length?

[@KyleP133]

Did you ever find out? Im curious too? Seems like you'd have to determine teh total travel of the hydraulic lifter plunger and add half of that to the pushrod length?

[@Saleen85111]

@@KyleP133 never found out.. guess we can always call them

[@maxxmasson4263]

You should have mentioned the camshaft position

[@vg23air]

if the person watching doesnt understand that, they have no chance of completing the task

[@brucetyson5077]

Base circle

[@turbojoe9554]

If I turn a 7/16" nut down 5 turns, the pivot point of the rocker arm travels down the stud .250". But the rocker arm is not symmetrical, in that it has, say a 1.60 ratio. So if the pivot point goes down .250", does theoretically the valve would "lift" .400". Am I off base here?

[@OldAndGettingOlder]

Man on man this is an excellent video. A grade schooler can understand this. Thank you.

[@Smooth73chevelle]

Awesome explanation!!! With a flat tappet hydraulic cam and lifters. Do I need to use a special modified lifter or would a normal lifter be fine for this check? And I assume the lifter would be sitting at max lift on the cam? Correct?

[@bradjones6363]

Never have installed a roller cam or rockers before, using the half lift method make sense to me theoretically, just wanted your input and see if my thinking was right on this. Averaging the lift between intake .515 and exhaust .530 on the Lunati 20510711 roller cam .5225 half that .26125/.050 is equal to 5.225 turns past 90 degree point with the valve. So if I stop at 4.5 turns + 1 flat of the adjusting nut to measure for the pushrod, then when it’s installed it would be 5 turns + 1 flat or half turn past zero lash and that should center the roller on the valve stem and set the preload on the lifter?? Will this keep the pushrods all the same length or do you need to do one length for intake and another length for exhaust?

[@HenryPanza]

Really nice explanation, but like smooth73 mentioned, there is not info on the lifter used and its placement. Confusing for some folks that don't know to make sure the lifter is max lift and make sure it doesn't collapse (which it shouldn't when using checking springs)

[@HenryPanza]

Scott Foxwell scott, yeah sorry about that. I was referring to folks determining their "max lift" of their at the valve to get their number, in your case .711. and YES finding pushrod length is done with cam on base circle. I see about a month ago you updated your post. Its a really good video and I know its easy to forget and assume people know certain things.

[@curtisdefreece9921]

This seems like a good way to check, wasn’t even close on my sbc 383. I’m not sure how it could be when there is a 1.6 rocker ration and mid lift at the valve is different than mid lift on the cam

[@straubtechnologies]

You use your rocker ration that your are using to get your lift. YOu then use half of that.

[@curtisdefreece9921]

@@straubtechnologies I think I need a different rocker arm. I measured it with the mid lift method and came up with bassically the same pushrod length but my rocker is way to the outside of the valve stem towards the exhaust.

[@jeffreydurham5342]

​@@curtisdefreece9921different rockers may help. How close to the edge is it? Centered doesn't mean good.

[@jeffreydurham5342]

If you've got 0.300 lobe lift and a 1.5 rocker, you have 0.450 lift at the valve. With a 1.6 rocker you have .480 lift. All this without including lifter bleed, deflection etc. Just divide the theoretical lift by 2 and put your rocker down that dimension from a right angle with the valve closed and the cam on the base circle. I'm working on a video, there's so much confusion on this subject.

[@jedwebster8976]

Mr. Foxwell, lots of mixed info out there about finding true TDC, how to degree the cam, check it’s specs and measure piston to valve clearance, too. Would love to see what you have to say on these matters. Thanks

[@jerrodwilliams6789]

I have brand new summit heads that i spend over 1100 dollars on for this small block 350 and have just discovered that i am having .008 variances in valve stem installed height. It was throwing me for a loop trying to set up this rocker arm geometry. Is it common for you to see this? Do i need to send it to a machine shop so they can grind the valve stem tips. I have also heard stories of new heads having .008 valve seat runout straight out of the box.

[@TD6297]

Hi Scott, I am curious, how would you apply this to BBC shaft rockers like T&D or Jesel? I can see, how it would be easy to roll the engine to half lift and check the 90 degrees, is that the only way with that style rocker? Do you have anything posted I can look at on this? I love this video itself, it made the visualization quite easy, thanks!

[@michaelcouey1383]

First off, I'd like to thank you for this video (even though it is many years old now). It makes perfect sense. I was all revved up to go out and do this on my motor. However I ran into a problem. I marked my rocker arm as you did here, but when setting it up on the head, I actually have to RAISE the push rod side of it to try and create the 90 degree relationship. The problem comes in that I run out of threads long before I hit that perpendicular angle. Any insights?

[@micthegreasemonkey2918]

That was a new way of doing it very enjoyable but still will be measuring both ways just 2 make sure of everything.

[@KyleP133]

Simple and easy to understand, but what do you do with hydraulic lifters? How do you adjust for getting the lash set to the middle of the hydraulic lifter's range? Do we add that to the length?

[@Hungry_Hippie227]

You get a solid lifter or make one outta ur hydraulic lifter. Once you get length set you add either .042 or .050 for me I had got 7.4250 on my flat tappet hydraulic lifter. Added .42 and got a length of 7.8450. Which gave me a perfect 90 degree angle on my 1.5 rocker arm at half lift.

[@shanelynch6261]

Everything is the same, just add the preload to your measured length. Typically 1/2 to 3/4 turn.

[@sgames6773]

The problem I ran into using this method is: when using valves with +0.200" length and lash caps +0.080" the resulting height causes the intersection of angles between the rocker stud and the valve to become such that the roller tip is far to much toward the exhaust side of the stem. So I'm having to find a happy medium between this method and center, or not so center of valve methods.

[@straubtechnologies]

We have corrected rocker arms with the geometry to fix this. www.straubtechnologies.com

[@johnvineyard67]

if you were to use a sharpe..and mark the whole valve stem top, and rotate the valve train. where would roller tip ride on stem..? do you check that..? it could not be center,,?

[@marcelnowakowski945]

I understand you measure the pushrod having the particular cylinder at TDC. Do I understand correctly?

[@joegarcia3520]

Great video. It appears my screw in studs are too short and I can't get to the 90 degree point.

[@gregg4164]

Now i get it. thank you very much. Now does rocker arm degree change any of these dimensions such as going from a 1.6 to a 1.7 degree rocker arm?

[@jimflinchbaugh335]

great information! The unanswered question is, you say you need to get the correct rocker arm first. Do you have a video on HOW to get the correct rocker arm? I'm assuming someone makes custom rocker arms? Currently building and AFR headed BBC engine, customer brought Harlon Sharp aluminum roller rockers and they are no where near being correct as you show. The rockers studs supplied by AFR appear they will much too short with a correct arm, but how to determine the correct arm is the mystery. Thoughts? Thanks!

[@straubtechnologies]

Most aftermarket heads have longer valves and longer rocker studs. These are both on a crash course of intersection. We have rockers with adjusted geometry to compensate for this. www.straubtechnologies.com

[@ClassicSilveradoTrucks]

Is the Gross valve lift determined on the exhaust or intake lift? My cam is .479 intake and .465 exhaust. Thanks! Great video...

[@chrisp1204]

Dare I call this an introductory, no obligation, gift. Absolutely Free! Shirt, pants, wallet and watch... ✔️. I'm not waiting around for the catch here, this is simply well articulated, sound advise offered to showcase a preview of what potential, existing and past customers shall receive. Thank you sir.

[@StanleyBlack-xf3hv]

I have watched dozens of these videos on push rod length. Every one of them shows a small block Chevy being used with stud mounted rockers which are the easiest to establish pushrod length. Not one video have I been able to find where a small block LA mopar with shaft mounted rockers being used. The process of establishing proper valve geometry and pushrod length is a bit different and more difficult than a Chevy. Shat mounted rockers require shims to raise the entire valve assembly to proper heigth which moves the rockers closer to the valve in order to obtain proper valve tip contact with rocker . This increases pushrod length plus adding the proper preload adds to the pushrod length as well. I guess not many racing shops are versed with mopar, therefore not having the expertise on how to build one.

[@straubtechnologies]

WE have 2 circle track SB Mopars going together over the winter. We are planning a video on shaft rockers and geometry on these engines.

[@StanleyBlack-xf3hv]

@straubtechnologies9011 be looking forward to watching the video when it becomes a available. Not many people enjoy the world of mopar due to their inability to build one. Having said that, the after market industry makes us mopar fans suffer when buying parts for mopar because the prices of parts are based on junkyard motors like Chevy. The variety of parts are not readily available for mopar as they are for Chevy and Ford. I will say though, if a die hard Chevy guy ever got behind the wheel of a car with a well built mopar, he push all that Chevy junk out of his shop and learn how to build some real power, lol, just saying.

[@arturozarate1752]

​@@StanleyBlack-xf3hvhere ya go bud....it's for an FE but shaft mounted all the same. kzbin.info/www/bejne/npS1hYKBo5WmoKcsi=qM5Q1d1179hVq1o5

[@335seth]

Hi Scott I just have a question about rolling the motor over with the push rods out. I bought a car that the guy told me needed a head gasket.He started the job but quit about a year ago,the motor has been left with injector rail and exhaust manifold off I want to see if the motor is froze and if I need a new motor or just the head gasket

[@doublecheeseburger1712]

How does head gasket thickness affect these measurements? I still will need to clay my pistons for valve to piston clearance, so I will just snug down head bolts against gasket to measure for pushrods....hope this makes sense

[@straubtechnologies]

Without the gasket in place, the true distance for the pushrod to extend over would not be accurate. A head gasket has a compressed thickness, how thick it will be once the head is installed and torqued, that could be something like 0.028". If that is not present at the time of taking the measurement, then your pushrods will be indefinitely short compared to what they should actually be.

[@davidkepics1644]

So after following you procedure my sweep was .045" but only .090" from the exhaust side of the valve stem. Is this acceptable? Before my sweep was .100" and was dead center. It seems that you are fighting a loosing battle here because the valve stem and rocker stud converge the farther you go up on the stud?

[@justinballard4134]

I had the same problem I ended up with .050 backset crower rocker arms

[@hotrodswoodshed7405]

@@scottfoxwell9810 thx for clarifying this issue... it's one that happens often... but few people address it with a tutorial. Even i was confused

[@jimrinnovatore7927]

I understand your methodology. I have 2 questions though. 1) You take 1/2 of the gross lift for your measurement. Wouldn't you use 1/2 of the net lift (taking lash into account). 2) Your pushrod measurement at flat to flat makes sense, but that did not work for me when measuring for TFS pushrods. They seem to measure not from the flats, but somewhere on the bevel. Had to go .050" shorter to get what I wanted. Comments??

[@Epistuff]

Scott Foxwell Scott, thank you for the prompt and detailed response. BTW.. who do you get the pushrods from?

[@mrbadpliersstripbolt2696]

+Scott Foxwell You mean a solid lifter? Not being a smartass, just getting all my ducks in a row.

[@mrbadpliersstripbolt2696]

+MrBadpliers Stripbolt Never mind. Just read the next comment. Thank you for taking the time to post this detailed information.

[@rjgarciasr]

Not sure what my problem is, but there isn't enough stud height to aligning the rocker at a 90° angle to the valve stem. With the lock nut only 2 full turns the angle is about 85°. :(

[@GroovesAndLands]

I got a set of Flotek 180cc aluminum heads for a warm 355 SBC for a ski boat. Can't remember the pushrod length Flotek recommended, but it was WAY too short to acheive the 90* angle shown in this video. As the pushrod was getting about long enough to hit the 90* angle, I ran out of rocker stud height. Had to buy a new set of ARP rocker studs. Somebody is totally wrong on PR length - either Flotek, or the guy in this video. I went with this guy. Hope it works out for me.

[@Dave-id6sj]

So I can expect my engine builder to do this properly for me when they put the engine together with the parts I supply, plus whatever machining they have done to bring a nearly 300,000km 302 Windsor back to life? For example the cam I want has to have some mods done to the heads, the heads will be Edelbrock, both cam and heads won't be crazy can't drive it to the shops. I'll have roller rockers (and cam obviously), but will have to leave pushrods until the engine builder tells me what I need? Along with head gaskets if they had to take much off the deck height and any impact that will have on the intake manifold I wish to fit. Just curious as to what to ask and what instructions to give them.

[@fingers967]

This video is great but could you explain how this method is going to work when you have a shaft rocker like on a mopar small block early LA engine with comp adjustable roller rockers.I dont know the thread pitch on the adjusters . plus how does this relate to the use of lash caps ,which I often do to create a wider wipe area on the valve stem for the roller tip.. hmmm

[@inscoredbz]

i checked mine on my 383 sbc with a retrofit hydraulic roller cam & lifters using this video & i got that it needs a 7.650" push rod. how much more do i need to add for the lifter preload? the lifters i'm using is Street Performance Hydraulic Roller Lifters, i'm not sure how much preload they require. the sweep pattern is on the exhaust side just about 3/4 of the way across the valve tip, but the sweep pattern is only about .040" wide.

[@jdhman177]

I am currently using this method to calculate pushrod length. the problem I am running into is that the roller tip contact is very far towards the exhaust side of the valve tip. it's not rolling off but it's close. 1.5 ratio rockers on a 7/16 stud. Where can I get the correct rockers to solve this issue? small Chevy.

[@chevroletbelair1]

I have Howard link bar lifters (ford 289l) do i have to think about the hydraulic lifter preload? Of do just this method and order this length without plus or minus preload setting?

[@mitchellfay5725]

At what position should the lifters be at? Bottom of lobe where valve is closed top of the lobe where valve is open? Just when the valve starts to close?

[@straubtechnologies]

On the base circle.

[@chickenfoundation9323]

So gross lift is lift of the cam or lift with rocker arm?

[@chassisaligner]

couldn't be explained any better. good job

[@deonreddy8661]

Great video! .... one question though not directly related to the discussion. Any ideas on the best possible way to combat valve float ??...... all comments will be much appreciated!

[@Mo-sf7wc]

Great video and explanation. I'm going to give your method a try. Question. Using hydraulic roller lifters. Do I need checking springs? It appears I wouldn't since I'm going to just add for lifter preload. What do you think? Thank you