Just got my valves cut in with NEWAY. Got the 351M back together and bent another pushrod...damm-it!
They're collapsing as I predicted, and during a start-up, they'll fall out of the socket and ram the side of the rocker arm. The 351 heads are funky, that some of the pushrod guide holes are just big enough to see the pushrod through, and the rod cannot tip away from the rocker arm socket if that lifter has collapsed from sitting awhile. There's only four guide holes in each head that are like that, and the other four pushrods have wide and large cut-aways in the cast heads for those pushrods to fall away from their rocker sockets and become bent.

What I need is some fabricated pushrod guides that are made for the 351C or M, and either mount under the nearby headbolt, or mount under the rocker arm fulcrum bolt. I have .30" shims under the fulcrums at this time, so .30" - .50" thick metal guide material should work under either of those bolts for a mounting of the guides. If the lifter collapses, the pushrod will stay inline with the socket until the oil pressure pumps it back up.

Does anyone know where to find metal guides like this for the 351C or M ?

 

....... pfffffffft

 

Why are you using 0.30" shims under the rocker pivot studs? With the 351M/400 you put oiled but not pumped up lifters on the cam in the lifter bores, then put the push rods in and then just tighten the rockers down. When you space the base of the stud up 0.30" you likely created over half inch of free space at the push rods so the push rods will fall out of place. The ***** on the ends hold them in place and oil pressure pumps the lifters up eliminating excess room. With shims, you're creating space the push rods can't bridge. There is no need for guides rubbing push rods, the rocker arms will pivot on the ***** to a natural point and the push rods has to be free to move laterally with them. You are bending them when the cam is on low lobe base and the rocker stops at closed valve and the lifter drops away from the push rod and the push rod falls out of place either at the lifter or the rocker arm end.

You should have a copy of Tom Munroe's book. My copy is from the early 1990s, only the cover changed.
I recall something in it about guides, but it was maybe referring to something in the 429 or 460s? I've got a '77 and a '79 and have been in others, no shims under rocker arm studs.

 

Shimming a positive stop rocker arm is no good
Even if someone makes shims for them, what and why come into play
Machining those rocker pedestals down and installing screw in studs is the fix
Then the guide plates mount under the screw in studs
Do it now or later, you choose
Bend as many pushrods as you want
You got interference
Roughly the same thing happened on the first Boss 302 motor I built
I had interference and bent about 20 expensive pushrods before I figured it out
My machine shop had not milled the pedestals down far enough for a guide plate. They were planning on screw in studs only

 

I'm not finding anyone making pushrod guides for the positive stop 351, and it would have to be my own fabrication and design - it appears.

I am running the lifter "collapsed tappet gap" near the upper range .150" -.165" (.071"-.193" FORD '77 allowable / .096"-.165" desired), which is why I am using some .020" & .030" pedestal shims under the fulcrums in my newly machined heads (the new intake valves had slightly longer stem tips also).

Pushing the "lash gap" down to the lower limit of .070" may be enough to keep the pushrod from dropping out of the rocker seat during a bleed off, but then there's the potential problem of over-pumping the lifter when the engine is running (I may consider doing this with the four lifters that cannot be extracted with the intake manifold on.)

I can pull those 4 lifters out through the large cutaway without pulling the intake manifold, and installing washer shims inside the lifter body like I had planned and talked about in previous threads. This would prevent those hydraulic lifters from bleeding down when the motor stops on that particular valve in an open position.

The other 4 pushrod cannot ever bend regardless of how much beed-off occurs because they're guided enough to stay inline with the rocker ball seat. one or two pushrods may "tick;tick;tick" at startup though while the oil pressure builds up

I just wonder how things would work if I got longer pushrods and ran those hydraulic lifters way deep down near the collapsed point with about .040" of lash at the rocker tip ? There was a lot of clearance that I measured between piston and valves in my stock 351M...do you think there would be an interference if the said hydraulic lifters over-pumped their reach with oil pressure during engine operation ?

 

Ford racing sells a shim kit with shims of various thicknesses to help adjust the valvetrain if necessary. I've used them a few times when setting up a non adjustable valvetrain with an aftermarket roller rocker arm when I ended up with a bit too much preload. I've seen them come through on Ford 3.0 V6 heads and it looked like it was factory.

With that said for normal use where the plunger is placed makes no significant difference in performance, near the top, near the middle or near the bottom all works fine. Hydraulic lifters do not "pump up" at high rpm unless there is valvetrain separation happening. If the spring loads are adequate they collapse as the valvetrain actuates and they lose height. This is why on a hydraulic camshaft design the lobe usually has a ramp that's about .006 high. This is the amount that they are assumed to collapse in the running engine so it is high enough to allow the valvetrain to close the valves without causing noise.

For high performance it is generally best to have the valvetrain set up so that the hydraulic lifters are nearly bottomed out. Within about .005 or so from going solid. This way when they are run at high rpm and the collapse the hydraulic lifters don't have far to go so they tend to behave more like a solid and less duration is lost. I've got an engine set up like this for a circle track customer who's required to run a functional hydraulic flat tappet with a stock style wire clip. I run it this way to try to keep the plunger away from the clip so that it can pop it out when the engine is revved up. The lift rule is only .430 so I've got a spring on there with a pretty high rate. So far so good after a couple of seasons.

Are you trying to do something like that?

 

At high rpm the valves float, that makes / allows the lifters to pump up to maximum
The lifter plunger will be at the top (not the bottom) so at high rpm there is no more pump up to occur, they are already pumped up about to maximum
New valve seats will put the valve back where it needs to be for a positive stop application
You run into trouble when cutting / grinding valve seats too deep into the head

 

It used to be thought that it worked that way but it doesn't. The only time the lifter can ever get longer is if there is separation in the valve train. Having the plunger adjusted right near the bottom and then giving it more spring load so that separation can't happen allows the valvetrain to have better high rpm control and make more power due to having less loss of duration and lift at high rpm.

In applications where a hydraulic cam is really appropriate usually under about 6000rpm it doesn't make any real difference to performance.

 

Is that like the one where you swear the coolant does not need to remain in the radiator long enough to get cooled?
Respectfully, you are dead wrong again, Dave

 

Really? In what way am I not correct on either topic?

 

Yes. I have removed all the shims from under the fulcrums. I had .020" under the exaust valves that did not have the extra valve tip extensions (the new exaust valves were the exact same length as the old). I had .040" under all but one intake valve to account for the extra tip length that the new intake valves have (we talked about shimming the pedestal to account for this extra tip length before).

I was going to shim the lifter plungers solid nearly to the top where the clip is, but last-minute decided not to try that un-tested approach (to do that now means pull the damned engine out again) ..... so.....gonna try another approach first in locating the pushrod closer to bottom-out - which may be enough to prevent the "ball/socket" from throwing out and away to far after a bleed-off.

With the fulcrum shims removed, there's three intake valves with feeler gauge readings under the tip at .060, two at .075, two at .100, and one at .031. I could add a .020" shim for the 31

I don't remember, but am guessing the rocker arm is 1.7:1, which could result in a bleed-off lash of about .035" on the pushrod end when there is .060" lash on the valve tip, and .044 with .075" tip lash. I may cut the two .100" fulcrums down to .075.

I would guestimate that .044" would not bleed far enough to slip the pushrod out of the socket unless something else (like stuck valve) occurs.

The exaust valves are probably near .100 -.120 without the shims.
UPDATE: most of the exaust are .080" one at 120 and one at .100

I wont be running the engine at 6000RPM, so hopefully there will not be any pump-up issues to contend with.

What a pain in the *** sqeezing the oil out of those lifters to measure the new lash!!

 

I did not think of that condition that the pushrod could fall out when it all falls back down off the cam lobe. But that too would only occur at a start-up where the oil has bled down. Is that not so?

 

If you have the rocker properly torqued down (25fp I believe, no adjustment) and the correct preload the lifters should not be able to collapse enough to toss a pushrod.

 

The preload is the feeler gauge thickness at the rocker tip. It translates 1.5:1 (thereabouts) less at the push-end of the rocker - which translates the same as how far the lifter plunger can collapse before hitting bottom inside the lifter body. This also translates how far the pushrod can possibly fall away from the rocker socket and/or the plunger socket.

I had the preload set within spec's (.070 -.190), and more closely to .160" by using .040 & .020" shims under the fulcrums - and a pushrod slipped out somehow.

I'm gonna give it a try with the shims removed, which lowers the feeler gauge preload to about .060 - .100" on most, with just one of the valve preloads at a loose .120". If this still does not work, I'll get Melling's .063" over pushrods, and re-shim under the fulcrums again until I can get an even lower preloading - like DaveMclain said he does (.005") with his race cars.

 

I was looking for .020" oversize length pushrods of the older classic 9.500" x 5/16" hollow tube type with ***** at both ends.

The nearest size longer I have yet found is .060" over by CompCam, .063" over by Melling, and a .090" over by Melling also. I could not find a .030" over either that could also fit my needs. I cannot use the 3/8 type (interferes with the cast iron guide hole).

Anyone know where the lesser .010, .020, .030, .040" oversizes can be had ?