my 68 f250 390 has the tapping under the valve cover described in other posts as lifter tapping. i pulled the valve cover and checked the rods. i did not see any bent or broken rods. the tapping seems to be in sinc with the #6 valves, and i saw one rod that was spinning as it went up and down.

i need some suggestions on what to do. i don't know anything about lifters or valves. to be honest, i really don't want to pull the intake manifold because i just got it sealed tight last fall.

a couple of notes: the heads were exchanged (stock) about 4K back, with hardened seats. when i took the manifold and rocker arms off last fall, i mixed the push rods up, not knowing they could be different lengths. however, they are old rods (not changed with the heads) and I suspect they are originals. i don't have the proper tools to measure them.

however, last fall everything was running sweet. then it pretty much sat over the mild winter (No. Cal) except for the past few weeks I needed it daily. the mild cold made for hard starting, so she would sputter. the more she sputtered, the rougher it idled, and then the tapping started after highway driving.

yesterday i tightened the exhaust manifold bolts and changed the plugs and wires. also changed the oil and ran some mystery oil for a short time. the tapping is still there.

thanks in advance
mike F250 CS 390 with petronix ignition

 

Push rod turn(spin) is normal.

Not keeping them in order is BAD.
They are supposed to stay mated to the rockers.

You need a metal straight edge to look for equal height on all the exhaust valves and then again on all the intakes with the rockers loosened.Using a feeler gauge is good for locating a difference.

Mark the push rods especially # 6 as you mentioned and remove them to measure them.

Before yo do this though ,with the engine running get a feeler gauge and measure the gap on the rockers to Valve stem.
*MARK THE RESULTS DOWN* one at a time on a piece of paper before
you shut it off and loosen the rocker nuts.




Dennis https://www.ford-trucks.com/user_gallery/sizeimage.php?&photoid=1733&.jpg



Please Don't Ask Me Any Tough Questions,
"I'm Saving My Memory For When I Develop Alzheimer's"


78 F-150 429CJ,Silver, Explorer Pkg.
641/2-Mustang 260,Pre-World's Fair Car.
64-Fairlane500 S/C waiting for a 390-4spd.
68-Mustang 289-Sunlit Gold 80,892Mi
78-Buick LeSabre 403 4V
84 Volvo DL Wagon

 

be patient with me, i'm sure this is simple to you, but valves are all new to me...
>You need a metal straight edge to look for equal height on
>all the exhaust valves and then again on all the intakes
>with the rockers loosened.Using a feeler gauge is good for
>locating a difference.

but i'm gonna place the straight edge across all the valve stem tops at once right? and just note on paper intake vs exhaust gaps?

i couldn't find a good breakdown of the valve system in my manual.. do intake and exhaust just alternate? is there a rule? (left is intake right exhaust looking from the side fender?)

>remove them to measure them.

i need a special high tolerance gauge? or a tape measure?

>Before yo do this though ,with the engine running get a
>feeler gauge and measure the gap on the rockers to Valve
>stem.

ok, does this mean, stick feeler guages under the rocker while its hitting the valve stem until i get one where the rocker stops moving?

alright, now the really stupid question...how do i use the info: tallest valve gets shortest pushrod?

thanks

 

>be patient with me, i'm sure this is simple to you, but
>valves are all new to me...
>>You need a metal straight edge to look for equal height on
>>all the exhaust valves and then again on all the intakes
>>with the rockers loosened.Using a feeler gauge is good for
>>locating a difference.
>


>but i'm gonna place the straight edge across all the valve
>stem tops at once right?

>>>YES<<<

I forgot to mention checking the torque on the rocker nuts first.
to see if any are loose.


and just note on paper intake vs exhaust gaps?

Make a diagram and label the clearance if any, on the corresponding valve


>i couldn't find a good breakdown of the valve system in my
>manual.. do intake and exhaust just alternate?

The exhaust valve is adjacent to the exhaust port into exhaust manifold


is there a rule?
(left is intake right exhaust looking from the side fender?)
>>remove them to measure them.

Just mark them ( front to back #'s 1-8 )each side


>i need a special high tolerance gauge?

Get An Automotive Feeler gauge set with various thicknesses.

>
>>Before yo do this though ,with the engine running get a
>>feeler gauge and measure the gap on the rockers to Valve
>>stem.

remember check the torque on the rocker nuts.

>
>ok, does this mean, stick feeler guages under the rocker
>while its hitting the valve stem until i get one where the
>rocker stops moving?

NO ,Until you can't put the feeler gauge in between the gap anymore.
>

>alright, now the really stupid question...how do i use the
>info: tallest valve gets shortest pushrod?
>
No stupid actually good..

Because you mixed the pushrods up, and the fact that the heads(valve seats) were done, we have to try and establish if they are all the same or not.

So, Don't worry about that until we know if all the pushrods match and how much gap the worst ones are.


>thanks

Dennis https://www.ford-trucks.com/user_gallery/sizeimage.php?&photoid=1733&.jpg



Please Don't Ask Me Any Tough Questions,
"I'm Saving My Memory For When I Develop Alzheimer's"


78 F-150 429CJ,Silver, Explorer Pkg.
641/2-Mustang 260,Pre-World's Fair Car.
64-Fairlane500 S/C waiting for a 390-4spd.
68-Mustang 289-Sunlit Gold 80,892Mi
78-Buick LeSabre 403 4V
84 Volvo DL Wagon

 

 

the good news is, after doing what you asked me toand putting it all back together, the tapping is gone!
for good? i don't know. like i said, i changed plugs, wires and oil.
Laying a straight edge over the valve stems, i measured the gap, if any:[table border='1'][tr][td] [/td][td]1[/td][td]2[/td][td]3[/td][td]4[/td][td]5[/td][td]6[/td][td]7[/td][td]8[/td][/tr][tr]
[td]Exhaust[/td][td]zero[/td][td]zero[/td][td].010[/td][td]zero[/td][td].020[/td][td]zero[/td][td]zero[/td][td]zero[/td][/tr][tr]
[td]Intake[/td][td].010[/td][td]zero[/td][td]zero[/td][td]zero[/td]
[td]zero[/td][td]zero[/td][td]zero[/td][td].012[/td][/tr]
[/table]
With the engine running, i tried to stick my smallest feeler gauge (.010) between the rocker arm and the valve stem. Granted, the rocker hits the stem at an angle, allowing the gauge to slide in about half-way, but i could not slide the gauge completely under any arm. (Maybe i did not do it right?)

I could not find a 9" outside micrometer to measure the pushrods, so i placed them between two straight edges on a table and tried to see if there was any difference in length; i don't think that was very accurate, but i could not measure any difference in their lengths.

I will tell you what i think might have happened. Usually when i discover some special placement of bolts, i will remember it next time or write it down. I do not remember ever noticing that one of the rocker shaft bolts is longer on the other to allow space for what i guess is an oil outlet on # 3 and #6. so possibly, even though i torqued the bolts to 40lbs, i may not have had them placed correctly, and so the long one may not have been flush to the shaft. i'm not sure.
but i am still interested in what these measurements tell you.

 

It just tells know how sets of rocker to rods are wearing.
If the numbers were worse and all the parts are the same ,to look at lot closer at other areas.

Dennis https://www.ford-trucks.com/user_gallery/sizeimage.php?&photoid=1733&.jpg



Please Don't Ask Me Any Tough Questions,
"I'm Saving My Memory For When I Develop Alzheimer's"


78 F-150 429CJ,Silver, Explorer Pkg.
641/2-Mustang 260,Pre-World's Fair Car.
64-Fairlane500 S/C waiting for a 390-4spd.
68-Mustang 289-Sunlit Gold 80,892Mi
78-Buick LeSabre 403 4V
84 Volvo DL Wagon

 

Thanks. I learned a little more today.
So, bottom line, the measurements look normal?

If this is becomes a recurring problem, would you recommend converting the rocker arms to adjustable? A mechanic suggested it, and I guess Crane has a set. $300 though.

 

Definitely !

I guess you feel pretty good now ?

Go have some fun !

Dennis https://www.ford-trucks.com/user_gallery/sizeimage.php?&photoid=1733&.jpg



Please Don't Ask Me Any Tough Questions,
"I'm Saving My Memory For When I Develop Alzheimer's"


78 F-150 429CJ,Silver, Explorer Pkg.
641/2-Mustang 260,Pre-World's Fair Car.
64-Fairlane500 S/C waiting for a 390-4spd.
68-Mustang 289-Sunlit Gold 80,892Mi
78-Buick LeSabre 403 4V
84 Volvo DL Wagon