AFR Tech: How to determine proper push rod length with Alex Taylor
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- เผยแพร่เมื่อ 16 ต.ค. 2024
- Alex Taylor demonstrates how to find the proper push rod length for your engine when installing new Air Flow Research cylinder heads. For this video we use a 6.0 LS engine that was pulled out from a local pick-a-part yard.
The information on this video doesn't apply to non adjustable rockers. Verifying the wipe pattern is part of setting up the valvetrain but on a stock rocker LS, lifter preload is the #1 reason for measuring pushrod length. Also, a tape measure to check pushrod length? A precision measurement where the tolerances are in the .005" range (depending on application) is NOT taken with a tape measure. Micrometer is best , cheap dial calipers minimum. Also, a ton of time & effort can be saved by setting the checker in place and threading it out until it sits in the rocker arm cup.
That was actually an easier to understand video than most I've seen. 👍
Great presentation--organized, methodical. There are two additional things I would have liked to see on this video.
1. Better closeups showing more clearly the white pattern on the valve stems.
2. Since some builders may be opting for roller rocker tips, it might be informative to see this demo performed using roller tipped rocker arms.
Use a dial indicator on top of the rocker to measure slack, then add the demension to the top of the adjustable pushrod. The dial indicator has to be measure right above the pushrod not the middle of rocker. Just help get a number closer to proper length pushrod.
Alex is a great spokesperson. Guys I am patiently waiting for AFR to make a head for my 440 dodge super stock clone. Hoping you guys might have something to go with Scat's stroker kits.
Just ordered some small bore enforcers for my stroker 5.3 turbo build...cant wait to get to the point of figuring out what size push rods I need. Very helpful video to prepare for that. Yee yee
Can't leave the stock valve springs in and pull a pattern on the valve stems with hydraulic lifters. The pushrods will be pushed down to the end of travel on every rotation.
This video is a mess! Didn't anyone from the AFR tech department double check this? The basic idea is solid, but with a bolt down non adjustable rocker all you are doing is adjusting lifter preload. You have to raise or lower the fulcrum (middle) point along with push rod length to make the pattern change like she was hoping. Most adjustable rocker systems use the stud and polylocks to do this, but I have seen a shim system for certain bolt down rockers like a 5.0 or Vw bug that can be used to raise the fulcrum.
Weird not hearing someone say,
"What's up,Guys"
Personally I would not use the checking pushrod to rotate engine with regular valve springs. I use light checking springs.
Good spokesperson!
This video does not even address valve train geometry. At all. The axis of the rocker needs to be 90° to the valve stem at half lift. On a pedestal rocker or shaft, that's done by shimming the rockers fulcrum height relative to the head. THEN you can select the proper length pushrod.
Or you can just bolt crap together. Either way 😆.
kool.thats where I'm at from replacing ol bent rodes caused by a timming chain😜
Great video Alex. No nonsense and perfectly spoken. It's a welcome change for this type of information. Keep up the good work!
simp
There is just a little bit of an easier way to do that how I do it is I put the push tube in there close to stock height and wrap a boot lace around it install The Rocker and then you just pull on either end of the boot case until you get all the slack out then measure it and send off for a new ones. It makes it easier than trying to get your fingers in there and it also makes it easier than taking the rocker off 50 times
how do you measure the pushrod?
I have a stock genv 454 that I’m putting 71 chevelle 454 bbl heads on will stock 3/8 push rods work ?
7.400 should be good on a stock deck LS3 ?
Not always cause if they used a small base circle cam then what?
Well.... Im confused. By installing a longer pushrod on this all your doing is changing lifter preload, nothing to do with rocker geometry. The rockers are fixed in position unlike a conventional rocker stud. I'm either missing something or this video is almost completely useless/misleading, which coming from AFR is very disappointing. Happy to be corrected.
Hi Damian, you are correct in that the height of the lifter is fixed because of the factory stand/pedestal. However, you still need the proper length push rod for valvetrain geometry. More specifically we are talking about the wipe pattern across the tip of the valve. On Hydraulic Roller setups, preload is important and the recommended amount can vary depending on which manufacturer you ask. But once the lifter is pumped up it acts similar to a solid lifter, which is why some folks will suggest using a solid lifter when checking for proper length on Hydraulic setups. This is because you don't want to collapse the lifter during verification, as it will give a false reading; another reason for using light weight "test" springs. I hope this answers your question.
Your comment comes across rude and the video explained it very well
@@Alexbuilt My comment does come across a little harsh but it's still correct. Im surprised one of the technical staff haven't quietly removed this video. By changing your lifter preload you will very slightly change the sweep but lifters call for a very specific preload so it's not really something you can control. Now if you start shimming the pedistal stands to 'fine tune' your preloads, something I've done before, then you will start to change rocker geometry but on such a small scale that it would be difficult to even see. Some correct methods are used in this video but on the wrong valve train/wrong engine.
I understand completely what he is asking. On a shaft rocker there is adjustment at the pushrod socket on the rocker arm but on this system the only adjustment is in the pushrod. In this instance, to get the correct witness mark on the valve stem, preloading the lifter is necessary.
@@Sluganaught666 You are correct. The technical staff at AFR should have removed the video and made a new one with better supervision. I am surprised that so few people know the fundamentals of how the rocker actually works. Forty one comments and just a handful actually grasp what's wrong here.
7.400 the lords length
What the heck was that she dont know what the heck she's doing what a mess AFR would be ashamed she dose not know how to do that.
I'm getting ready to swap to Mongoose heads !
I feel bad for the people who are going to attempt this at home with a hydraulic lifter with no oil in it.
you should prime the engine first to get the oil in the lifter right
Not to mention telling them that pushrod length will move the pattern on a non-adjustable valve train.
And that's ignoring the fact that the ''find the middle of the valve'' is NOT the right way to set up geometry.
Just the tip.. Am I right boys?
I guess so if that's all ya got
"Great spokesperson" and yet the video fails to convey correct information on the task at hand. Methinks viewers don't care about the content, just the appearance of the presenter.
🔧🎓🤝
Sorry I didnt hear a single word.
😂😂😂😂
hi
hi although pushrod length is great idea , time would be better spent on a chevy cyl head application advice . Surprisingly being heads are your main product your still giving the wrong advice for application . Multiple calls to your advice line b4 a proper calculation was done for the application
Try having a 195 comp head on 400cuin ,breathing thru a straw when should have been a 220 to rev a 400 to no more than 6500rpm .
Be cautious of the advice
a 195 comp head breathes 300 CFM on a 4.125 bore 400 and has 2.08 vales.
Youd think thats almost dead nuts for a pump gas 400 going to 6500 but you need at least a comp 294HR cam and 10.5:1 to do it....and an 850 and the single plane comp intake they sell. youre not gonna do it with the dual plane i would think on a 400
a 220 on a 400 should be like 7000+ man....those can breathe on a 434..
Airspeed thru the port MCSA minimum port cross section 195cc has to overspeed on a 400cuin
227 afr 400cuin 12.5 cr 260/270SR peak hp 640 at 6800-7000rpm .
220 best at 6500rpm with lesser cam /eng specs
@@paulthompson1654 skip white builds a similar combo with AFR 195 and a Howard's 245/253 cam and a single plane. 550 @ around 6000 and that's with non CNC enforcers and 2.02 valves. So about a 6500 rpm redline. I should make that clear. Those 220s are a about 7000+ rpm redline on a 400
Keith dorton also built a similar combo that made 550 with 195 heads.
A 210 AFR head would be really good on 400 with solid roller
@@KingJT80 Even AFR agreed , once they got serious and did some airspeed vs mcsa calculations . Even a restrictive head will flow if u give it enough camshaft . BUT you will make more tq and hp with the correct size cyl head mcsa.
Volume cfm is only one criteria for head selection .
@@paulthompson1654 well they tell you which heads work for what right on their page. Usually it's the redline of the engine. ILl concede a 195 comp/street heads have about a 6500 rpm redline on a 400 seeing is how there are a ton of people who run that combo for a pump gas street 400
A 210 would probably go to a 7000 RPM redline on a 406. A 220 would be nice on a 421/427
AFR 227 starts to get pretty big and the headers start changing
😍🥰🥰❤️👈🏻👌🏼😎
All wrong you have no idea how much pre load is on the lifter and if you use a real spring it will bend that pushrod checker.
Not the proper way to do this, couple key steps are skipped. Whos running things these days?
Please for the love of God. Don't measure push rods with a tape measure