I have a new little problem. I need to know the exact size of the threads on an original 69 351W pressed in rocker arm studs.
( what size bolt holds the rockers on? )
( what size bolt holds the rockers on? )
Brad,Are you sure?
All so far it you read the thread have said that they are 3/8.. Hmmmm
Wish I had a way to check for sure..like a thread size chart or something.
Bob, thanks for the reply. Sorry it hurts to type..Brad,
Some 351W (the non-adjustable type) had 5/16" fine THREAD studs, the shanks of the studs were 3/8" just like the adjustable ones, except the adjustable ones have 3/8" fine thread and 3/8" shank.
You know the difference on sight between 3/8" and 5/16", right? It really should be just that easy.
Another dead giveaway on the non-adjustables is the shoulder (stop) where the 5/16" thread ends and the transition to 3/8" begins.
Hope this helps (b/c it hurt to type it! ;-)
5/16" nut and shouldered stud = NA, 3/8" nut and non-shouldered stud = A.Bob, thanks for the reply. Sorry it hurts to type..
I don't think I ever knew that there were differences in the 351W. Of course I only have been dealing with the 69 heads. What do you mean by "adjustable" and "non-adjustable".. ?
My studs are factory pressed in, they are threaded down to a point and then not threaded, and the rocker nuts seemed to be tightened down until they stopped and then torqued. They are the "rail" type of rockers, you know factory ones like all the small blocks (289, 302, 351 ) I thought they were all the same.
Nice heads. Good info. thanks.. I might be interested in the heads as a back up set. what are the date codes on them and what condition are they in??? Of course shipping would be horrible, ???I just went to check they are 5/16 fine thread positive stop type
They came from a 1969 351 in a 1969 Mustang GT
Still have the motor wish I still Had the Car
My heads seem to be as all my other 351W heads were. Your NA.5/16" nut and shouldered stud = NA, 3/8" nut and non-shouldered stud = A.
A = adjustable lash
NA - tighten to shoulder and then torque
3/8" (A) nuts will run all the way down until the threads end.
I could be wrong, but if you have NA valvetrain, you may not have a 1969 engine (or at least heads). What are the casting #'s on the heads?
Not date codes but casting #'s (should be C9xx, i.e. C9AE)
NA to my knowledge did not appear until sometime after 1969 (70-something).
Earlier. I just thought that '69 was before the fixed setup, maybe I'm wrong. Anyone?...Maybe the bigger thread and adjustable type is for a later version??
Bob, your typing is getting better. Good drugs and an interesting "Cougar" question can do that for you. I appreciate all the input you have.Earlier. I just thought that '69 was before the fixed setup, maybe I'm wrong. Anyone?
The numbers I was was looking for are on the underside of the intake runners in the lifter galley area. If the heads are on the car, you would need a dentist mirror to see the numbers.
Still thinking '69 was adjustable, someone here must know when the switchover took place...
BTW, on the 5/16" NA valvetrain, poly locks are unnecessary as their purpose is to better retain adjustment on an adjustment of an adjustable valvetrain. Not even sure they make Poly Locks for 5/16" NA studs.
Sounds like you are all set then, just nags me as to when the switchover from adjustable to non-adjustable occurred. I could have sworn that the (original) 351W I took out of the vert had adjustable, but my memory could be wrong....The poly locks may be necessary as the rockers are a bit taller and thicker and the original factory nuts won't fit inside the rockers. The 5/16 polylocks should do the trick.. Any thoughts Bob.?
Bob, I have been on the phone with the manufacturer's Tech dept. and this is where we are at. What is available that is closest to right are 3/8" roller rockers. They come with the corresponding 3/8" poly locks. That is what I got. Fine. Now we know that the 69 351W are non adjustable 3/8" pressed in rocker stud with a 5/16" NF thread end and "positive stop" rockers with a "fulcrum" ball washer and 5/16 NF threaded nut. ( from this thread and much additional research ).Sounds like you are all set then, just nags me as to when the switchover from adjustable to non-adjustable occurred. I could have sworn that the (original) 351W I took out of the vert had adjustable, but my memory could be wrong.
About the PL's, why aren't you getting the right ones from the place you got the wrong ones from rather than buying them a second time? Just wondering.
So, all's well that ends well I would say. You have a solution and we may have learned something (would love a definitive answer on the studs though...).
Brad, I think you (and we) have put more than enough thought into this and I am sure it will be fine....I just can't see where if half of the approx. 3/4 to 1" of 3/8" internal bore of the roller fulcrum is over the 3/8" portion of the original pressed in stud that there will be any substantial play. I will adjust the lash on each valve as per the spects sheet that came with the rockers. Any thoughts???...
That would be good Bob.. I would certainly like an additional example other than my cats.. I suspect it will be the same.BTW,
Since we got nothing definitive on this (besides your data Brad), I will (when I get a chance) pop a valve cover off my original 351W engine from the vert and (if for no other reason) satisfy myself about the 5/16" NA or 3/8" A valvetrain in '69.
I will guess based on what we do know that mine will be NA too. Maybe the changeover was from 68 (A) to 69 (NA).