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correlate the deflection to crankshaft degree's and you'll find it's less than 1 degree. not enough to worry about.

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many builders let the pushrod touch the valley wall to reduce that

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Are you referring to motion lost from the rockers sliding sideways on their shafts as they pivot? The stock springs that kind-of act as spacers seem to allow a lot of sideways movement, something I've noticed on mine. Decades ago Landy sold collars that kept the rockers in place fore/aft. If I ever take mine apart again I'll do something like that.

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Hey Daryl; Don't feel bad I'm seeing those numbers or more with my solid roller and production rockers. It is what it is. Try a set of stock pushrods, they flex like a wet noodle.Dave

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How are you measuring in a running environment? I have run those DLI stainless rockers and dont think its a problem. I was running 800 lbs open pressure too.
Id say it's worth zero to very little power, unless its making 1400 hp or something like that. I just dont see those rocker flexing that much. Id say its in the push rods... They are so long. I cant recall how long my custom Manton's were but they look like a ram rod from a muzzle loader.

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How are you measuring in a running environment? I have run those DLI stainless rockers and dont think its a problem. I was running 800 lbs open pressure too.
Id say it's worth zero to very little power, unless its making 1400 hp or something like that. I just dont see those rocker flexing that much. Id say its in the push rods... They are so long. I cant recall how long my custom Manton's were but they look like a ram rod from a muzzle loader.

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I'm measuring in a static environment. I would think it'll only get worse as RPM's increase.
I have broken down the deflextion between pushrods & rockers. This is real world numbers, as measured:
total deflection- .042" deflection,
pushrod deflection- .010" @ valve (approx.)
rocker deflection = .032"

I am running alot less spring pressure than you @ 600 on nose. I don't know how you can say it's not an issue. Loss of valve lift is loss of valve lift, whether it's a 400hp pooch or a 1400hp ball breaker. It's all relative, & more prominent on the higher HP stuff.

liteweight

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What size pushrod diameter and wall thickness are you using? What srping pressures? Those long puppys do deflect a lot, like most women will tell you, stiffer is better on some things Especially pusrods I used a set of Manton 7/16 thick .167 wall thickness single tapered pushrods on my 527 Indy 440-1 headed motor. PM me if you want some,I'm a Manton and Smith Bros. dealers, I give Mopar members a better deal than you can get when you buy direct, unless your W.D for them

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Any clearance issues with 7/16" in the block or head??

liteweight

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That is one of the things that must be checked, it may or may not be a problem. It depends on block and head castings, lifter cup hieght and many other things that we can't control Back in 1968 or 1969 Don Purdome(SP?) was one of the first racers to use and let it be known thhat the D&D tapered pushrods help his top fueler dragster 426 Hemi motor increase the useable RPM range by almost a thousand RPM by changing just the pushrods and tune up in the motor do to the increase in engine RPM caused by the stiffer pushrods revving higher BTW, be very caeful on letting the pushrods rub on anything, those tapered pushrods are not cheap and they will die young if the cups don't get any oil due to being held up and not releasing from the adjsuter to let oil into the cup Don't ask me how I know I bought three exhaust pushrods due to this I now make sure they spin easy and do drop down to allow oil into the cups, no rubbing ,even on the head gakets now, for me

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With rocker deflection your valve timing will be retarded

True, but only when the spring load reaches a critical level - it won't delay the opening ramp.
Unfortunately, the deflection is fairly stable in time units but the valve train is obviously working at engine speed.
This means that the deflection will occur earlier relative to the CL as RPM goes up. The deflection also unloads at some point, and adds the missing valve motion at a time the spring didn't anticipate. There is a "crack-the-whip" effect when this happens that unsettles all the VT pieces and it's scary to watch on a SpinTron. If actual air gaps occur (the parts are completely separated) something will break.
Some cam manufacturers factor in compliance (i.e., some lobe motion being used up in compressing or bending some parts above the camshaft CL, including the cam itself, pushrod, rocker, rocker stand, etc.) when designing ramps and accel data, but IDK which ones or how to tell.

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Hi Daryl !
While the DLI rockers were the answer back in the day and the finest there was , The Barton units will do away with all of the problems you are experiencing . They are pricy but would sure seem to be the answer. Not the answer you were looking for , but surely something to be considered .
chryco


Hey Rob
I know the Jesel ,T&D's are the best out there for many reasons, but dude, I just can't justify $5k for the application I'm going to use this motor for. I want to drive the Dart this year, & I have 2 more hemi's I need to finish. Plain & simple it's about the $$$$. It just don't go as far as it used to.
Did a bunch of measuring & comparisons today between stock, Indy & DLI. Not surprisingly, the stocks flexed the most, but the Indy's were not far behind. The DLI's had the least amount of deflection. What did surprise me was the amount of deflection that is occuring with less than .250" of valve lift. It is definatly affecting the valve timing in relation to the piston. Valves are opening later, your not getting the valve lift you might think your getting, & the valves are closing earlier. It's not 1 or 2 degrees, or .005 - .010" either.
With the numbers I'm seeing on my motor it has me thinking if I purchase a different set of rockers, I'll order them with more ratio, just to make up for the loss of lift from deflection. As far as timing, I think I'm going to start checking at the valve with the intended to use springs, instead of degreeing it at the lifter.
I'll post some measured numbers later

AND, Still waiting for some input from Stage V users .

liteweight