SDPC Tech Tips: Pushrod Length
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- Опубліковано 23 сер 2024
- In this video, we go over the use of a pushrod length checker and why it is so important to do when installing an aftermarket cam or finishing up a fresh build. Don't leave it to chance, getting it wrong could ruin all of that hard work, damaging the engine, or it could possibly leave power on the table!
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What a great video. Everyone tells you to check length but no one shows you how to do it to this extent. Thank you sir. You made my build a bit less stressful.
Dude 3 years ago maybe you guys won’t see this but wow amazing video thank you so much!!!! I have been searching and searching and trying to understand push rod length and this is the only place that has given me any useful information!!! Thanks guys awesome video!!!
Dude, this is the most informative video I've ever seen.
I am in no way shape or form building an LS or will be in the future.
But still one of the most informative and easy to understand videos I've ever seen.
Nice work!
I just had my heads done, a 3 angle valve job and .030 milled off the heads, this helps to determine if 7.35 is what I need, where can I get the adjustable pushrod tool from. Great video!!!!!!
ive built many harley twin cam engines. typically most builders would use adjustable pushrods in them. I never did like them they are weak af. however getting the exact amount of lifter preload was extremely important. especially when using S&S lifters with limiters in them. they are still hydraulic but have a limiter in them that keeps the plunger from collapsing at high rpm. I used them in my engine when i built it and i probably checked and rechecked the lash a half dozen times before i was confident it was right. My screaming eagle instructor was a ahdra drag racer. knew his shit, when your setting zero lash on a lifter you should be able to spin the pushrod with one finger without and up and down movement on the rod or rocker arm. simple explaination and it worked. good content and thank you
Thank y'all for this channel really gonna help for my first LS 5.3 build!!
Very professional easy to follow great teacher. I watch a lot of engine building-tuning some guys got it some dont. Keep up the great work looking forward to more of ur videos.
Thanks
Josh
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.
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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.
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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.
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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.
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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.
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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
Great info, I’m kinda concerned though for someone who’s gasping for air while standing still. His health is pretty concerning.
You’d be surprised how much the microphone pick ups we wouldn’t normally hear
I appreciate the information lately I found that setting the lifter lower in the travel may be helpful if the lifter bleeds down pretty quick .
Great video. I rolled my pushrods on granite to see if they were straight before installing them. I found several that were bowed oquite a bit in the center.
I returned them until I had all straight pieces. Silly? LOL Like they say, a bent pushrod is just a stiff spring! LOL
Very informative and easy to follow along vid
I also have new stock push rods and rocker arms,rails ,which was going to be my next step ,would that help?
Excellent video!!
When you got your final measurement, you were checking for lash on the rocker, how come you went with that measurement if it still had that slight lash when you rocking in vertically?
Yeah, st2126lsr lifters with oem rockers took freaking forever.
thank you very helpful
Very helpful!!
Can you explain how you know you are at zero "lash"? Is that on the bolt or on the tip of the rocker?
Thank you very informal
Yes sir just watched a few of you videos,great references to watch,I have few questions. ,you said ask.3GCRKSE35AG111737 is my Vin on 2010 chevy gen4 5.3 vortec ,had a misfire on 8 and ticking .dissambled,found lifter clip cam off,ordered all GM parts ,lifters,holders, bolts head gasket ,intake manifold gaskets ,everything went together nice and torque to specs,new wires coils plugs. Now it runs fine but#6 is misfiring?? Truck driving me stressed,cam was fine, all rods and rocker arms labeled and installed in same spot, did I miss something?, any ideas that can help my truck?
Does the tool take into account that 7.400” pushrods, for example, don’t measure 7.400” tip to tip? In other words, does it measure 6.800” tip to tip when fully closed or different to account for that?
So I am doing a DOD delete on an L99. Based on what I just watched, the FIRST thing I need to figure out is what camshaft I want to use, right? Then from there, I can go down the list of the other parts I want to order.
Yes did you decided which cam?
I have a problem. I have a 98 4.3 V6 that I have put a comp cam 266HR cam. .500 lift. I used the stock hydraulic roller lifters and I feel like the lifters are not giving the valves the full amount of lift. I have comp cam LS Beehive Springs so there is more seat pressure as well as maximum over the nose. Are the stock hydraulic roller lifters adequate for this much lift and pressure? I did not think at the time I built the engine that this engine was that radical. thanks!
When I’ve done it, I wouldn’t rely on pushrod turns, I would measure the rod length.
I don’t think you can measure tip to tip though. Maybe I’m wrong, but a 7.400” pushrod doesn’t measure 7.400” tip to tip, for example.
I have Chevy 383 with solid roller lifters was going to deck the heads about .010 do i need new rods?
If is a SBC not a LS have to get the rocker and pushrod geometry correct on the valve tip and then use feeler gauge to correct lash as majority of SBC rockers are adjustable. .010 generally no you don't need new pushrods but if your trying to reuse the stock pushrods for any performance I would upgrade.
Great vids....I had someone put a stage 2 sloppy cam in my 6.0..new oil pump and chain,gaskets..he said I needed new pushrods so he got manleys 7.450 -7.500 ..he put them in and when I picked up engine he said 2 of new ones were to long ??? He measured them...do you think I have to worry ? I was going to do new spring kit....just dont want to have any problems Thx
Everyone uses this method. But what about rocker geometry. This method wont guarantee that rocker centreline is at 90 deg to the valve stem centreline at 50% lift. Has everyone forgotten about this important measurement with LS Engines ?
maybe mention the engine type? This wouldn't work for a sbc....
So were you at 7.400"? 7.350 + .050 preload?
Right.... that’s not confusing...
7.350 or 7.400 is with the preload. And both are within tolerance.
once you order pushrods and add in preload, then torque them down is there still play? i did mine and checked and checked and checked. then ordering them installing them and after torqueing them there is no play. So should the play still be there after installing them??
Once pushrods have been installed and the rockers are torqued down, there should be no play.
Hi guys my ls1 pushrod measurements range from 7.310 upto 7.315 Would I go with a 7.370 push rod length.
7.325 is what we would recommend with those measurements.
@@Sdpartscenter I have ls7 lifters, how much extra to allow for preload. Regards Darren
Thank you for your knowledge and videos USA 🇺🇸 TRUMP
how about a ls7 can in a 6.0
Don't bother get an actual aftermarket cam you're gonna lose a bunch of bottom end
7 L cam in a 6 L, i think the ls7 is physically bigger
there's an easier way to do this with a sharpie.
move your mic further away from ya face, use a boom mic,