Rocker arm stud nuts

[turbotim2]

Stock 69 302.

The book I have shows the the rocker arm stud nuts should be torqued to 17-23 ft-lbs. As I tighten them down (I can only get about 10 ft-lbs as the nut turns down), they just open the valves until the nut gets to the bottom of the stud. This is leaving all the valves open even when they shouldn't be. What am I missing here?

 

[crews44]

I believe that torque spec if for pedestal style rockers...if you have studs I usually go 3/4 turn after you reach zero lash

 

[turbotim2]

OK, well that makes a lot more sense! Thanks!

 

[.94 OR]

You might double check that the nuts have some "grip" left in them. I am working on my '71 302 and the nuts spin freely by hand so I know they will likely not keep the correct tension. I ordered locking nuts from Mr. Gasket, but the wrong size showed up. Until I can get the correct ones, I just ran some spare nuts down to act as jam nuts once I got the rockers set. My specs show to turn the nut 1/4-1/2 past zero lash. Not sure if there is that much difference between these as this is a fine thread stud.

 

[Scott C.]

There are 2 different types of studs. The early 289 and 302 heads have a straight stud and those are adjustable just like a Chevy. The later ones had a shouldered stud that you torque the rocker arm down to. You might have the adjustables valve heads. The later pedestal or solid fulcrum type used bolts to fasten them to the head and not a studs.

 

[Broncobowsher]

How far is the valve opening? If it is just a little, then you are OK. The lifter is fully extended, when you tighten the rocker the valve opens first, then the lifter bleeds down until the valve closes. Most of the small block Fords are this way. The nuts do not have "tension" on them, they spin on the threads freely. This is different then a small block chevy. If everything is factory and correct, you did it right.

It gets more difficult when parts start getting changed. Non-positive stop studs, screw in studs with guideplates and other performance parts can change the standard bolt down and run valve train into an adjustable valvetrain. That is when you need special nuts with the crimp on the end to hold the adjustment (or poly locks that use an allen set screw to lock the adjustment). But those should not be needed unless specific work has been done that requires them.

 

[broncnaz]

X2 on the different studtype there are positive stop and standard adjustable type sounds like you have the adjustable type. Which you dont torque. The valves shouldnt open any when adjusting the rockers if they are you are either adjusting while the cam lobe is in the lift postion or you have adjusted to far.
As was said positive stop type studs have a shoulder where the adjustable type are straight.

 

[Steve83]

X2 on the HLAs bleeding down after you tighten the nuts to the specified torque.

 

[turbotim2]

OK, the first one a tried to tighten all the way down opened the valve all the way and then bled down the lifter and the valve remained open with no cam lobe lift. This one has stock lock nuts, straight pressed in studs.

 

[.94 OR]

Hopefully something you don't have to deal with is uneven stud heights. I have 3 that are a hair higher than the others. With these the rocker assembly bolts all the way down until the nut runs out of threads and the rocker is still loose. I have had to get some washers to put under the nut to take up the extra room to get the rocker down where it should be. I'm hoping it isn't a problem, but I am watching those in particular to see if they fluctuate in their adjustment.

 

[broncnaz]

You have adjustable type rockers so the tighten all the way down and torque specs are not for you. Its you have to hit zero lash than adjust the nut about 3/4 of a turn more and your good.

 

[turbotim2]

Awesome, thanks. I just finished them up using your technique.

 

[.94 OR]

You might try something else while you are there. I pulled a valve cover off to see what I might find. I had the key off, trans in neutral, wheel chocked and a jumper cable on the starter solenoid. I was able to watch the rockers go through their motion.

As it turns out, I have the intake valve on #8 that is not working. It appears to be stuck in the closed position and all of the cam travel is absorbed in the lifter. Now I have to figure out what to do with it. The heads were rebuilt about 100 miles ago (rebuilt in 2003).

 

[broncnaz]

You might try something else while you are there. I pulled a valve cover off to see what I might find. I had the key off, trans in neutral, wheel chocked and a jumper cable on the starter solenoid. I was able to watch the rockers go through their motion.

As it turns out, I have the intake valve on #8 that is not working. It appears to be stuck in the closed position and all of the cam travel is absorbed in the lifter. Now I have to figure out what to do with it. The heads were rebuilt about 100 miles ago (rebuilt in 2003).

Most likely your cam has a flat lobe the lifter plunger doesnt travel all that far once preload is set there should only be about .200 or less travel left in the lifter while some cams dont have much lift you still should get some lift even if the tappet collaspes.

 

[.94 OR]

It might. Explains my habit of continually bending that push rod. I have to figure out where the valve is stuck. Not sure if it has slammed itself into the seat and lodged, or if it is stuck in the guide or bent. It acts like it has plenty of compression in that hole though.

 

[Scott C.]

.94 OR, your valve would not stick in the seat. It will stick in the guide. With no more travel then a lifter has to absorb, you might have a cam lobe worn down. If you have a lean burn problem you could suck the valve up into the seat from high heat. You would be able to see that as your valve stem would be higher than the others.

 

[.94 OR]

Thanks. I'm trying to dust the cobwebs off the grey matter. I had the heads rebuilt now 8 years ago. I just finally got the rig on the road 2 years ago and likely put at most 50 miles on it. I am now working on it again. If I remember correctly when I got the heads back I checked the valves and that one may have been stiff after being rebuilt but I had hoped it would run in over time. I guess not. I'm just wondering if I can unstick it without having to take the head back off.

 

[broncnaz]

You need to check the lobe lift on the cam for that valve to ensure that it hasnt worn down before worrying about wether or not its a sticking valve. Typically if its a sticking valve issue the valve will stay open not closed. If the valve is the issue then I would guess that the valve stem is bent.

 

[Scott C.]

If your heads set for 8 years, you should have taken them apart and lubed the guides beore trying to use them. They most likely rusted and stuck in the guide. Or, if the guides wre knurled, reamed or replaced, they could be lacking sufficient clearance. Then it would stick after it started building up heat. It sounds like you may need to pull the heads back off and check them out. Be sure to check your cam lobe and lifter too. You may need to replace the cam and lifters. Do not replace just a lifter on a worn cam. It will not work!!! The lifters are gound with a convex face. The cam lobe is ground at an angle. That causes the lifter to turn. This also creates the rearward thrust to keep the cam from walking forward and stretching the timing chain. If the lifter stops turning it will wear off really fast. Allways keep the same lifter on the same cam lobe when removing and installing used ones!!

 

[.94 OR]

Thanks.

I had fired the motor up several times a year to move out and back into the garage, so it wasn't like the motor was oil free.

I just put in a new cam and lifters last weekend. I am trying to get it fired back up and get the cam broke in. The stock lifter and cam lobe looked fine. With the valve cover off and the ignition off, I was using the starter motor to turn the motor over and noticed that valve not opening.

I'm tempted to knock the center out of a spark plug and braze a hose nipple on it so I can keep the valve up with compressed air while I pull the keeper and springs. I'm hoping I can decipher the issue without pulling the head, but may end up doing that anyway.

Edit: The spark plug trick worked excellent. I was able to hold the valve up while I took the spring off. With a little finesse it freed up. I oiled the shank and it floated nicely so I reassembled it. Now I have to wait until tomorrow to get another plug and I can fire it back up. Granted, the valve was stuck closed so I didn't need the air to hold it up the first time, but once it was free, you need the air to keep the valve up to get the spring and keepers back on.