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Joined: Mar 2010
Posts: 1,371
B
Curmudgeon
" So, what I have is a fully rebuilt 261"
"This is a Canadian 261, so the hydraulics are OEM"

It would be divine luck to find new OEM hydraulic lifters, so are your lifters used originals that have been resurfaced or new reproduction?
Which leads to the camshaft. Reconditioned or new reproduction?

I hope this discussion doesn't spin out of control into a regurgitation about lifter design and cam specs.
It all been discussed here before and can be found by searching Stovebolt. Especially noisy hydraulic lifters.

Back on track now. I'm curious. Why do pushrods rotate? Maybe it's because the lifters also rotate?
I'm not a engine man like Jerry but I recall that you want the lifter to rotate a little bit for lubrication and to have and even wear.


"Adding CFM to a truck will only help at engine speeds you don't want to use."
"I found there was nothing to gain beyond 400 CFM."
Joined: Mar 2010
Posts: 1,371
B
Curmudgeon
I just now found this from jalopyjournal.com talking about a "F@rd":

New hyd. and solid lifters have a 96 inch spherical radius ground on them and the cam lobe has approx. 0.002" taper so that it contacts the lifter off center and spins the lifter.
Proper operation means that the lobe and lifter don't rub but roll together at the same surface speed.

Last edited by buoymaker; Sat May 21 2022 07:22 PM.

"Adding CFM to a truck will only help at engine speeds you don't want to use."
"I found there was nothing to gain beyond 400 CFM."
Joined: Feb 2004
Posts: 24,738
H
Kettle Custodian (pot stirrer)
Yep, you nailed it- - - -BUT- - - -the brand new milk can lifters we put in John's 261 when we assembled it were perfectly flat on the bottom (I checked). I'm not sure about stovebolt hydraulic lifters. The cam lobes on almost all engines contact the bottom of the lifter slightly off center so the lifter spins and equalizes the wear on the cam lobe and the lifter. Putting a slight radius on the lifter helps the spin action happen if a lifter happens to be designed that way. Yes, the pushrod spins because it's following the motion of the lifter.

I'm building a fixture for my lathe to allow me to use an electric die grinder and a Roloc grinding disc to resurface lifter bottoms and put the radius back into one that's worn flat. With the length of the lathe ways I have currently, I'll only be able to put about a 48" radius onto the lifter bottom. I do have an extra set of ways available that will double that length once I get them grafted together.
Jerry


"Freedom's just another word for nothing left to lose"
Kris Kristofferson

Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!

There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self.
Ernest Hemingway

WAG MORE- - - - - -BARK LESS!
Joined: Mar 2010
Posts: 1,371
B
Curmudgeon
Go it. Thanks Jerry.
So I take it that the rotation of the pushrods MAY be a source of concern but it's not the cause of the original problem.
I would think the engine needs to run, varying speeds, on the road (loading the engine), for an extended period of time (circulate the oil).
What I'm trying to say is that maybe the lifters lost their pre-load of oil if the valve adjustment was too tight.
Hopefully they will recover as the engine runs in the future. If they don't, there is information on Stovebolt on how to manually pre-load.
I would only do the pre-load NOW if a lifter sounds like it is going to self-destruct.
My 2 pennies.


"Adding CFM to a truck will only help at engine speeds you don't want to use."
"I found there was nothing to gain beyond 400 CFM."
Joined: Jan 2016
Posts: 719
G
Goach2 Offline OP
'Bolter
Adjusted a few valves again, seems to be quite a bit quieter. I think it might have needed more warm up time. Timing was on the triangle, until it warmed up and now it's around the ball-bearing, so 6-7 degrees advanced. I think road test is my best bet to dial it in now.


1948 Chevrolet Thriftmaster 3/4 Ton
There are only 10 types of people in this world, those who can read binary and those who can't.
Joined: Feb 2004
Posts: 24,738
H
Kettle Custodian (pot stirrer)
The preload is there to allow the inner plunger of the lifter to run in the center of its travel. That way, there is never any loss of contact between the cam lobe and the lifter, and the overall length of the lifter and pushrod is able to compensate for pushrod and valve stem stretch and shrink due to heating and cooling without rattling or holding the valve open. The internal alignment of the lifter body and plunger is also best with the proper preload so any seepage of oil can be replenished by the oil pressure when the lifter is on the base circle of the cam with minimum load on the valve train. Since each lifter operates 60 times per second at 2K RPM, there's very little refill time available with the cam lobe unloaded.
Jerry


"Freedom's just another word for nothing left to lose"
Kris Kristofferson

Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!

There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self.
Ernest Hemingway

WAG MORE- - - - - -BARK LESS!
Joined: Jan 2016
Posts: 719
G
Goach2 Offline OP
'Bolter
Preload is the amount that the valves are adjusted, which slightly compresses the lifter?


1948 Chevrolet Thriftmaster 3/4 Ton
There are only 10 types of people in this world, those who can read binary and those who can't.
Joined: Feb 2004
Posts: 24,738
H
Kettle Custodian (pot stirrer)
Yes, as you tighten the adjuster after taking out any slack at top dead center, the "preload" is the distance the lifter plunger is compressed. On a 20 thread per inch thread like the stovebolt adjuster uses, 1 turn of the adjuster after reaching the "zero-lash" point would compress the lifter plunger 1/20 of an inch, or approximately .050". That would allow the lifter height to compress or expand a little to compensate for length changes due to temperature.
Jerry


"Freedom's just another word for nothing left to lose"
Kris Kristofferson

Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!

There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self.
Ernest Hemingway

WAG MORE- - - - - -BARK LESS!
Joined: Mar 2010
Posts: 1,371
B
Curmudgeon
Pre-load with oil. Pre-load of oil.
The procedure with lifter in a container of oil, plunger pressed down to expel any trapped air then slowly release to intake only oil.
It's possible the valves were adjusted too tight squeezing the oil out. If so it may have lost it's pre-load of oil. There may be trapped air inside the lifters.
After some decent running time the trapped air may work itself out...fingers crossed.


"Adding CFM to a truck will only help at engine speeds you don't want to use."
"I found there was nothing to gain beyond 400 CFM."
Joined: Feb 2004
Posts: 24,738
H
Kettle Custodian (pot stirrer)
Since stovebolt hydraulic lifters do not lube the rocker arms with hollow pushrods, air can get trapped in the lifter body and be very difficult to purge. That's the reason for the grooves in the bottom of the pushrod, and a vent hole or groove in the pushrod seat if there's not a weep hole in the center of the plunger. Dave's blog gives us some very useful procedures to make the lifters self-purging. Wherever an engine stops, a few valves will be open, with valve spring pressure trying to collapse the lifter. There might be a little bit of rattle on startup when those collapsed lifters are refilling, but it should go away in a few seconds, or a minute or two at most. Once the small block V8's and the 3rd. generation sixes started using hollow pushrods and oil flow through the lifters and pushrods to lube the top end, most of the hydraulic lifter problems disappeared. Unfortunately, it's difficult to modify a 235 or 261 engine to use tubular pushrods. (Not impossible- - - -I'm doing it on one engine I'm building).
Jerry


"Freedom's just another word for nothing left to lose"
Kris Kristofferson

Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!

There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self.
Ernest Hemingway

WAG MORE- - - - - -BARK LESS!
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