Something I was concerned also was the input oil hole on the side of the lifter body getting blocked from the sidewall of the plunger when the plunger is positioned deep-down near the bottom of the lifter body. There may not be enough oil getting through to the rocker arm if this hole passage way was restricted, and it is likely the purpose for FORD to limit the preloading of the lower specification to .070" minimum (.050" @ the pushrod end).

One way to test that, of course, would be to run the plunger low, and watch for normal oil squirting from the pushrods.

Do you know from experience that the oil gets to your circle-track rockers when you've got the plungers nearly compressed to .005 ?

 

Your overthinking this, it's not a race engine. First remove all the springs and measure the valve tip heights, make sure they are all within .010 of each other. To get new pushrod length, put a checking spring on in place of the valve spring. Then get an adjustable push rod, put cylinder on tdc. Adjust pushrod to zero lash. Turn crank through a cycle watching to be sure the rocker's tip stays on the valve's tip through a complete cycle. Remove and measure pushrod then add .030 to that length and thats the length you will need.

 

I'm setting all my 351M positive stop valve lashes to .050 -.060" at the valve tip. The newly installed ELGIN valves have longer tips than stock - and this results in a smaller lash. FORD minimum spec. is .070", and they recommend something over .096". The lifter plungers will be around .035 - .044" away from the bottom before they go solid. When the engine sits a day or two and one lifter may bleed down, the pushrod should still be within the crown of the ball, and slide back into the rocker socket while the oil refills the lifter.

 

I was able to position all the lifters for .075 - 100" positive stop lash. The pushrods that come through the wide access in the head casting were jacked-up with the lash shortened to about .050", by inserting a .020" shim washer under the lifter plunger. Those eight lifters cannot collapse more than that now, but the .070" FORD minimum spec is maintained for proper oil flow to the rocker arm. The other eight pushrods feed through 3/8" guide holes in the 351 head, and still have the full 75-100 to potentially collapse. However, the little preload spring inside the lifter may prevent the pushrod from falling out after a bleed-down at startup when the plungers are positioned deeply into the lifter range as such. I would guess that little spring is there ...just to keep the pushrod in the rocker socket !! That little spring gets stiffer when compressed near the bottom range of the lifter - rather than the top range - and that stiffness is what is needed to overcome the oil viscosity and push that pushrod back up into the rocker. I think you would bend rods forever without that spring !

 

Well, you simply argued with me about overheating, you said the radiator did not need the coolant to be in there for long
Same now with the 1/4 VS 3/4 down from zero lash
You do it any way you want
Float those suckers with hydraulic cams all you want
A quarter turn down from zero lash puts the lifter plunger at the top of its travel
I run solids in all of my hotrods
Like I said before, "where is your masters cert and what did you do yesterday"
I still fix cars daily
Yesterday it was a 2014 F150 coyote for the dreaded low oil pressure lamp on
Today it is ball joints on a Silverado (talk is cheap)
It takes money to buy whisky

 

What's a "masters cert"?

Yesterday I worked assembling a set of GM 3.6 V6 heads, grinding the valve seats in a set of big block Chrysler heads. Plotted two cams that came in for regrinds to see what was going to work when I regrind them, worked on the surface grinder that I just got to see what settings are going to work best for surfacing the sides of my masters and my index plates. I also had quite a few calls for technical information.

Compare the car radiator to a heater core. If I slow down the flow using a water valve does it make more or less heat come out on a cold day when the water travels slower?

Hydraulic lifters do not work like you think. They tend to reduce high rpm performance, not because the "pump up" but because they collapse and this reduces the lift and the duration right where it is needed the most by the engine.

Try this experiment; run a flat tappet hydraulic cam using solid lifters set up as a tight lash. Run it with a spring that gives adequate loads on both the seat and open to some rpm above 6000, say 7000rpm, measure the torque and HP output. Now replace the lifters with a set of hydraulics with the standard travel that are adjusted to something like 1/8th to 3/4 turn down from the top. Run the engine to the same amount of rpm. Now adjust the same lifters to about .010 from the bottom of the travel, re run the test. What happens?

I'm not putting you down or knocking you I'm just trying to explain to you and others that the well known ideas about how things work are not always true.

 

Put a restrictor in your heater hoses and go to Alaska, see how long it takes you to remove it
Hell yes you will have less heat
A Masters Certificate and trophy is what Ford gives you after about 20 years of school (after you pass all the ASE ones first)
Why would I want to try anything using a solid lifter, and compare that to the clearance ramps and also the plunger in a hydraulic lifter application?
I have no idea what would happen in your thought experiment for me

 

The radiator works the same as a little heater core. The only thing that having a restriction in the system does to improve cooling which it tends to do is to allow the pump to produce more dynamic pressure inside of the engine. A friend of a friend worked for the Elliott racing team for many years and I discussed this with him about 10 years ago when I built a 383 Cleveland for a Pantera customer to run in the Silver State Open Road thing in Nevada and I had questions about cooling. He told me that they in their testing they found a certain pressure above the static system pressure that they wanted to see inside of the engine for best cooling. Too high wasted power and didn't cool as well, too low didn't cool as well either and tended to cause hot spots to happen which could force out coolant. They would vary the amount of restriction and or the speed of the pump to get it just right.

Using the solid lifter on the hydraulic profile and running lash makes the actual profile get smaller than it would theoretically with zero lash and a hydraulic yet it will make more high RPM power and have better stability. Put a hydraulic lifter on the same cam and give it a small amount of preload. Now the engine is getting the full size of the lobe yet it will make less high rpm power and be less stable. How is that possible? It happens because the lifters bleed down as RPM increases, the cam loses lift but more importantly duration right when the engine really needs it.

This collapse happens for a variety of reasons, oil aeration and lifter body distortion and the amount of clearance in the lifter itself which controls its bleed rate.

.030 is not an unreasonable amount for the lifter to shorten at high rpm so using a plot from a Comp 280H check out what that does to the duration:

Comp 280H 280H w .030 lifter collapse
.006 282 240
.010 271 236
.020 255 230
.050 230 203
.100 198 174

Now if the same lifter is used but adjusted to within .006 of the bottom of its travel the duration looks like this, still a loss but much better and basically the same as if it were run as a tight lash solid:

.006 267
.010 261
.020 249
.050 225
.100 194

To alleviate fears of the the lifter "pumping up" or getting taller due to valvetrain separation (shouldn't happen with the correct spring loads) what people do is run a reduced travel lifter. It is still a hydraulic lifter but it can only travel about .030-.050 or so. Usually they also have the heavy duty Tru arc retaining ring so that the lifter can't fly apart as easily if this happens. Lifters are adjusted to within about .006 or so of the bottom and they can then bottom out and run similarly to a solid at high rpm yet if there's a mishap they can't ever overextend and cause problems.

 

@DaveMcLain With all due respect this thread was started by a person who is having valve train geometry problems. If you feel a need to pontificate on other issues start your own thread. Or give the guy some real help without typing a book.

 

You're right and I apologize for taking the thread off track. None of this stuff matters in a low RPM(below 6000) application.

 

I went back and looked at F250C's posts. His first post in another thread in April with the original unmolested engine was bent pushrods. He blamed it on bad gas, but now it's August and after a bunch of parts he still has bent pushrods.
I think he needs an exorcist or a mechanic.

 

The first bent pushrod was caused by a stuck valve.
The second rod likely bent from being to sloppy with lifting shims and a large valve lash on the positive stop 351 type.

I have since set the lifter plungers deeper without the lifting shims on the pedestals, with the largest lash being about .140".
Most lashes are around .070" of play to collapse, and 1/2 of them now have a shim washer underneath the plunger so that they have an even lower effective collapsable lash of about .050". .050" play is not enough for the pushrod to slip out of the socket and hit the side edge of the rocker arm - thus bending the rod when it binds the spring.

So far after about 6 miles of test driving the engine, it has not popped a rod as yet.

Now, the truck has been sitting for about a week, and there should be at least one lifter that has bled down to a collapsed condition. So it will be "slack" when the engine fires up, and will try to fall away from the rocker socket during the first few revolutions. And with the .190" slack lash as it was with the pedestal shims, the rod had plenty of a collapsed lifter length to fall away and then push up against the side of the rocker instead of in the socket - binding the spring and bending the rod. This is what likely happened to the second rod...and it was not caused by a stuck valve as in the first instance.

There may be some other ways to bend a pushrod, but I dont want to know !!!!

 

Dave, I did make 8 of the lifters limiting by puting a .020 washer shim under the plunger. The original lash (without a washer) is .080, and .020 lowers that as an effective 050-60. The washer shims could be placed on top of the plunger also to prevent pump-up, but I did not try that in my application. (I only shimed 8 of the 16 that I could reach without removing the intake manifold - is why only 8?) The other 8 pushrods wont slip away because of the narrow rod passageway through the head casting - it serves as a "guide" to keep the rod in line with the rocker socket.

So far - so good. I can add 1 or 2 more .020" shims under those 8 if a rod slips out and bends again. Hopefully not.

Thanks for the info, ed