Mercury Cougar Owners banner
1 - 19 of 19 Posts

·
Registered
Joined
·
2,853 Posts
Discussion Starter · #1 ·
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? ):confused:
 

·
Contributing Sr Motorhead
Joined
·
5,470 Posts
Those should be 3/8 NF (National Fine) thread which is 3/8x24NF. Normal National Course thread is 3/8x16NC.
 

·
Registered
Joined
·
2,853 Posts
Discussion Starter · #3 ·
Those should be 3/8 NF (National Fine) thread which is 3/8x24NF. Normal National Course thread is 3/8x16NC.
Thanks so much.
:)I think I have a set of 7/16 poly-locks instead of the required 3/8.
I will get on it..
 

·
Registered
Joined
·
2,853 Posts
Discussion Starter · #5 ·
my 69 heads have 5/16 fine threads in. Anyone need a set of 69 Windsor Heads
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.:confused:
 

·
Premium Member
Joined
·
13,578 Posts
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.:confused:
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! ;-)

Bob
 

·
Registered
Joined
·
2,853 Posts
Discussion Starter · #7 ·
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! ;-)

Bob
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.
 

·
Registered
Joined
·
48 Posts
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
 

·
Premium Member
Joined
·
13,578 Posts
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.
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).
 

·
Registered
Joined
·
2,853 Posts
Discussion Starter · #10 ·
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
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 got an idea and don't know why I didn't think of this before:uhoh:
I checked the original rocker nuts on my tap set.. duh.. 5/16 fits and as Bob said, the 3/8 wouldn/t even go in..duh..
 

·
Registered
Joined
·
2,853 Posts
Discussion Starter · #11 · (Edited)
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).
My heads seem to be as all my other 351W heads were. Your NA.
5/16 nut with a very visible shoulder. The nuts seemed to be tightened down to the shoulder when I removed them. All rockers looked good and the valve stem tops looked good and were flat, no dish at all. Internally it looks like a good 45k motor should.
Both my original low mile cats ( the convertible and this XR 7 ) are original motors as well as most everything else.
Looking at the XR 7 there is the 351 cast into it, the big "WF", cast in and the date code of the drivers head is "8H27" and the passenger side head is "8H10". All 351W original.
I have never run into any other type of head configuration on any of my 351W motors but I am only dealing with the 69 stuff. Maybe the bigger thread and adjustable type is for a later version??
 

·
Premium Member
Joined
·
13,578 Posts
...Maybe the bigger thread and adjustable type is for a later version??
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.
 

·
Registered
Joined
·
2,853 Posts
Discussion Starter · #13 ·
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.
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.
Yes, my engine is mostly together. There were no leaks on all the original factory gaskets from 69 so I am lucky there. The low miles mean that I will only restore ( repaint) what is necessary and replace only what is needed to put it back together. So the intake, heads, exhaust manifolds, etc are all still in place. I removed the valve covers to re-paint them and to check the rockers and push rods so the date codes on the heads are very visible and clear. The intake is 351W of course and the date code is close to the heads.
Nothing changed here or on my other 69 which has the same type heads with the rail ( self aligning ) rockers and 5/16 studs.
I am so glad to have the stud size situation figured out. Much thanks to all who chimed in on this.
I am putting on the stainless steel roller rockers to make the head components last longer and cut down on heat and wear. Maybe get a horse or two more. I have kept all the original rockers and nuts for whatever..The new rockers are 1.6 ratio, 3/8 self aligning. Should work great. They just sent the 3/8 polylocks with the kit. I have found a set of 5/16 poly locks on e-bay..
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.?
 

·
Premium Member
Joined
·
13,578 Posts
...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.?
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...).
 

·
Registered
Joined
·
2,853 Posts
Discussion Starter · #15 · (Edited)
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...).
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 ).
So, all the benefits that can be had with roller tip and roller fulcrum rockers are at the center of this. The best fit ones available are the 3/8" rockers. They are thicker, well built, and the "roller fulcrum" is machined to slip down over a 3/8" stud; which the original 351W has except with the 5/16 machining about 1/3 rd the way down. The new roller rockers 3/8" fulcrum fits about 1/2 the way down on the stud. The rocker has about half of it's 3/8" fulcrum over the 3/8" stud and the other half over the 5/16" threaded part. The tech. guy says that there may be play ( left and right ) that could cause damage and then again there may be no trouble at all. He was just being cautions as he should. I believe that there will be no problems. They seem to fit fine. I have found a set of 5/16 poly locks and will use them and go for it.
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???
( I do not want to change the original studs as they are fine and the rockers are reversable for a concours car; besides, you have to remove the heads to machine for the studs and there is no need to do this on this original running engine..not to mention all the work )
 

·
Premium Member
Joined
·
13,578 Posts
...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???...
Brad, I think you (and we) have put more than enough thought into this and I am sure it will be fine.

I think most of us would have went back to and left the stockers, but if it makes you happy, why not?! I certainly have done plenty of things just to satisfy myself (and no one else).

Happy Thanksgiving to all. Got the temp cast off today and now have a velcro deal. Still hurts quit a bit and have limited movement, grip, etc... Still, I will be back to it after vacation.

Bob
 

·
Premium Member
Joined
·
13,578 Posts
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).
 

·
Registered
Joined
·
2,853 Posts
Discussion Starter · #18 ·
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).
That would be good Bob.. I would certainly like an additional example other than my cats.. I suspect it will be the same.
Yes, I have given this enough thought. On with the rollers. The originals are in a box saved just in case. I like many other Cougar owners who work on their cars, don't seem to ever get rid of any part even it is unecessary or in terrible shape. I have a big box of old bolts and odd parts etc..
I was looking for one of the unique flat bolts that holds the water pump plate on because while cleaning them, my son lost one. Any, I didn't find a spare in there but did find many interesting cat pieces and spent over an hour just rummaging. Strange the things I can find to entertain me for an hour.:uhoh:
Keep on healing and eat plenty tomorrow.. It is good for the soul.
 

·
Registered
Joined
·
1 Posts
Cougrrrman:

Realize this thread is a few years old, but am hoping you are still out there and can help me with a similar issue.

I am building a FFR Cobra MK4 and have installed a 1969 sbf 302 engine in it. I thought while I had the valve covers off I would change out the stamped (stud mounted) rockers for some PRW 0330202 1.6 3/8" self-aligning roller rockers. My pressed in studs are like yours - 3/8" shaft with 5/16" threads. The PolyLocks that came with the PRW rockers have a 3/8" thread, so wont work on my 5/16" threaded studs. Ordered SpeedMaster PCE255/1001 PolyLocks from two different vendors (specs say they are 5/16 threads with an OD of .55". However in both orders I received PolyLocks that had 5/16" threads, but had an OD of .595" -- which wont fit inside the slot of the PRW roller rockers that I have.

Again, if you are still out there, would appreciate your guidance to a solution. I totally agree with you on the roller rocker fitting down on the 3/8" unthreaded portion of the studs and want to try that approach if I can find a set of polylocks that are 5/16" threaded and have an OD less than about .57". BTW, my current stamped rockers have a 3/8" slot in them and fit nicely on the 3/8" unthreaded portion of the studs!
Product Automotive lighting Audio equipment Font Gas

Blue Green Door Wood Font


Thanks

AggieCobra
 
1 - 19 of 19 Posts
Top