I went to adjust the valves on my fresh build today and found something strange. The adjusters on the high ratio rocker arms are the jam nut type, but the adjuster is 1/2" and the jam nut is 16mm. That can't be right! Against my better judgement, I began setting the valves anyway. Well, the adjusters were all over the place, so when I was backing everything off to check the pushrods, again, I noticed that the threads on the adjusters are starting to pull! These rockers were in the trunk of the '54 Ford my son bought when we got it, so I have no idea where they came from. The rockers seem to be original Ford pieces, but quite obviously, the adjusters aren't. Can I just swap out the interference type adjusters from the original low ratio rockers onto these or do I need to buy new adjusters? Thanks for your time!

There is on going problems & mis information re rocker arms & adjusters.. On behalf of myself & another Y-Block engine owner,  I made enquiries here some time back. Unfortunately, the info posted at the time wasn't very helpful. And I certainly don't claim to have all the answers. The 16 mm thread info is new & I doubt it's correct .  However, in 1957 or late 1956 (?) I believe Ford made available the  xxxxx B2 rockers with one piece  "interferience thread" adjusters. When they work correctly & aren't worn so as to come loose in service, they are fine. However, when worn or apparently if re installed into earlier rockers, the problems begin.. I would like to hear a proper & accurate review of rocker arm issues, including parts availability, &  accurate info on the interference threads & so on.  For instance, is the interferience thread on the adjuster or is the thread in the rocker arm different?  Anybody?  Thanks  


Paul

16mm is almost 5/8", close enough that 16mm and 5/8 wrenches can be used for the same purpose.  That's not out of the ordinary since the wrench for the jam nut must fit over the hex for the screw.

From what I understand, you have to run a tap through interference fit rocker arms before using jam nut adjusters.  Maybe not doing that can result in the pictured thread wear.  Jam nut adjusters should thread easily, like a bolt into a nut.  If they don't, something is not right.  You can verify the thread pitch with a thread pitch gauge and measure the diameter to be sure it is correctly sized.  20 tpi is very close to metric 1.25mm pitch.


Lawrenceville, GA

I did verify the thread pitch to be 20 tpi, but a 5/8 wrench would not even go on the jam nut. The adjusters do screw in easily, so i don't know what's up there. I just don't want to get everything together and have a failure because someone replaced some adjusters with Chinese copies or something. I don't have the greatest luck in the world. Lol!

I’ve been purchasing adjusters from Titan Industries. I have not for a Y-Block since mine are fine but for others engines I race. Since they manufacture for high performance including top fuel engines I have found their parts top notch..

56 Vic, B'Ville 200 MPH Club Member, So Cal.

Watch out, some of those aftermarket rocker adjusters and or push rods have the wrong size ball or cup and will never stay adjusted.

The ball seems good, but there's too much going on with these for me to trust them. The pushrods are original Ford pieces, so I'm thinking they're probably ok.

FWIW, I'd like to know too.

I have both the earlier A2 (1956) and later B2 (1957) rockers here as NOS items.  The A2 rockers came with adjusters using locking nuts while the B2 rockers are using adjusters with interference threads.  I removed the interference fit adjuster from a B2 rocker and the threads in the rocker are the same as the threads in the A2 rocker.  The adjuster from the A2 rocker screws cleanly into the B2 rocker meaning it is only the B2 adjuster that has an interference thread and not the threaded portion in the rocker itself.

Lorena, Texas (South of Waco)

I have found the same as Ted.  I was missing an adjuster from one car (lock nut) so I took one  off my other car (also a lock nut)and put it on my TBIRD.    I found and interference adjuster and put it on the first car and it worked as it should (it held up for many miles).  So the interference is in the adjuster, not the rocker arm.

I don't recommend using a interference adjuster on the lock nut rocker as the added height of the lock type rocker gives very little wiggle room for adjustment.  When I did the swap above, I had very little room to make any further adjustment other than stock clearance.


54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ