FE adjustable rockers

[Sid]

On the Ford FE 406 engine 1.76 adjustable rockers what is the desired # of threads showing on the bottom side of the rocker? Right now I will be at about 3 1/2 + or - with about 4 showing on the nut side. I have heard that some guys run as few as 1 thread showing on the bottom side. I would think the adjusted should be close to center in the rocker. This is a solid cam.

 

[40 Deluxe]

Solid or hydraulic cam? If solid, set at the specified lash. Number of threads showing means nothing. If hydraulic, I think the setting is one turn down past zero lash. Again, number of threads showing doesn't matter.
Now, if you have a reground cam, or different length valves, or a lot milled off the heads, you should check if the rocker arm is centered on the valve stem as it opens and closes. This is adjusted by changing pushrod length, not the number of threads showing wherever.

 

[scicala]

Good advice from 40 Deluxe. I never in my life heard of setting valve lash by counting threads showing ? Especially with solid lifters. Recipe for disaster.

Sal

 

[40 Deluxe]

Solid or hydraulic cam? If solid, set at the specified lash. Number of threads showing means nothing. If hydraulic, I think the setting is one turn down past zero lash. Again, number of threads showing doesn't matter.
Now, if you have a reground cam, or different length valves, or a lot milled off the heads, you should check if the rocker arm is centered on the valve stem as it opens and closes. This is adjusted by changing pushrod length, not the number of threads showing wherever.

Oops! Changing pushrod length only works on stud mounted rocker arms where the pivot point can be raised or lowered. On your 406 you have to change valve length or raise or lower the rocker stands.
I see you added that you have a solid cam. Definitely forget this thread count business and get out the feeler gauge!

 

[Sid]

I never stated I was setting lash by thread count. I may have been born at night but not last night. It is not uncommon that when you install an aftermarket cam,deck the block,or install new valve seats push rod length can be affected. It you pay attention to the rocker geometry on an FE you may notice that if the adjusting screw is all the way down (7 or so threads showing on bottom) as apposed to say 2 threads showing on the bottom it changes the angular position of how the adjusting ball rides in the push rod cup. I know that there is a recommended standard thread count below rocker arm for this especially when using aftermarket parts. I just need to find this recommended thread count. Also changing push rod length does affect the thread count above and below rocker arm.....

 

[40 Deluxe]

Thanks for 'the rest of the story'. I misunderstood. Sorry!
I think your next step should be to use Dykem or Prussian Blue on the valve stem tip , assemble the rockers and roll the engine over through one valve cycle. Check the tip to see where the rocker contacts the valve. It should be centered, not running off one edge.This contact pattern is affected by the length of the rocker arm from its pivot point on the shaft to the valve stem, and also by the angles formed by the valve stem vs. the rocker arm. If the valve and rocker form a 90 deg. angle with the valve closed, for example, the rocker may move to the edge of the stem when open. If the angle is 90 deg. with the valve open, the rocker may run off the other edge of the stem. This may put a side load on the valve stem and wear out the guides prematurely.
Changing pushrod length will not change this relationship between valve and rocker arm. I think keeping the rocker tip centered on the valve is more critical than the ball-to-cup relationship. This should take care of itself once the rocker/stem location is correct.

 

[TedEaton]

With the lash adjusted to spec, I would expect for an equal number of threads both above and below the rocker as being the ideal adjuster location. This is assuming that the rockers have the original 'friction thread' adjusters and have not been replaced with some that are longer than stock and/or have locking nuts on their tops.

 

[GOSFAST]

When working with ANY shaft-mount rocker setups you MUST establish the correct stand heights before you can check anything else.

The correct stand heights guarantee's the correct pattern on the valve tips during the opening and closing of the valves. This is your starting point, it's the same on any builds regardless of brands!

Once this is done you can begin looking for all the other dimensions, pushrod length, adjuster protrusion, etc.

When we do the shaft-mount Chevy's the stand setups come with shims for below the stands, this is extremely important for valve guide life among other things.

Below is a shot of the stands/rockers for a BBC, shows the shim pkge supplied with the rockers, this has been a "standard" procedure for any shaft mounts!

Thanks, Gary in N.Y.

P.S. The mfr of the rocker setup will have the amount of protrusion for the threads, in other words, where they want the pushrod contact to be. On a side note, be very careful with this particular rocker setup, just a few years back we had experienced a number of broken adjusters while dynoing the unit. Turns out there were a bunch of "defective" new pieces floating around, we got this info direct from the mfr of the adjusters.