312 Y Block valve cover studs

I thought I could just slide the bushing onto the stud and press it down with the valve cover. Not so.
The bushing was too loose and it just slide down the stud. I had to run a nut down and put a washer on top of that and than place the bushing on top.
I than had to run the nut up until the valve cover started to rock,and than back off until it stopped rocking.
I could see the bushing under the valve cover so I knew it was close.
Even then,the acorn nut just barely started on the stud.
Just one snag out of many.
 
Some of the 'replacement' style studs may(?) be very slightly longer than the originals, if that will help.
4.25 instead of 4.125 ???
Call the Parts or Tech Help phone numbers at these example places to confirm.

https://hillsresto.com/

https://www.classictbird.com/

http://prestigethunderbird.com/

The engine in photo 2 comment #19 above came up short one of the original studs and the machinist put in one from his personal collection of original parts. I paid him back with another original, because the new ones aren't the same.
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The engine in photo 2 comment #19 above came up short one of the original studs and the machinist put in one from his personal collection of original parts. I paid him back with another original, because the new ones aren't the same.
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It seems to me the problem is either the stud or grommet or a combination of the two. The stud should have a chamfer to stop the grommet. Most likely either late replacement stud/grommet is not made to original specs.

Same on valley pan grommets. Many describe having to cut the grommets to have the hold down bolts not to stick up too far.

Once upon a time and many GALAXIES away, the rocker cover and valley pan grommets were different. Now the manufacturers use the same grommet for both positions.

If having to use a nut on the stud to capture the grommet, it might be best once the proper height is established to run a pal nut under it if enough threads to keep the nut from running down the threads due to vibration losing the seal.
 
...the rocker cover and valley pan grommets were different. Now the manufacturers use the same grommet for both positions.
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Well, I stand correctd.

It seems the same grommet was used for both positions so the sizing problem(s) must be the aftermarket vendors.

Below are the specs to measure against the store bought -
 

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KULTULZ said:
It seems to me the problem is either the stud or grommet or a combination of the two. The stud should have a chamfer to stop the grommet. Most likely either late replacement stud/grommet is not made to original specs.

Same on valley pan grommets. Many describe having to cut the grommets to have the hold down bolts not to stick up too far.

Once upon a time and many GALAXIES away, the rocker cover and valley pan grommets were different. Now the manufacturers use the same grommet for both positions.

If having to use a nut on the stud to capture the grommet, it might be best once the proper height is established to run a pal nut under it if enough threads to keep the nut from running down the threads due to vibration losing the seal.
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I thought about the pal nut,however once I ran the nut, with the washer, down to where I could test the height of the valve cover to where it would stop rocking, there was less then the height of a pal nut left showing on the stud.
Amazing, short on both accounts.
I am not sure if there would be that much vibration with the rubber grommet compressed.
I guess back in 1957 it just stayed under the valve cover using the snug rubber fit. But ,back in the day things were made of sterner stuff.

Thanks all.
 
Patrick brophy said:
. . .I guess back in 1957 it just stayed under the valve cover using the snug rubber fit. But ,back in the day things were made of sterner stuff.

Thanks all.
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Under the valve cover? As shown in reply # 16 back on page 1 of this thread? I've never seen that before.
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I have seen some of the TB aluminum valve covers cracked around the bolt holes because they were over tightened.
 
Patrick brophy said:
Well now, don't I feel silly.

It appears that I am right back where I started.
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Don't feel silly as I am the one that showed the Ill. The more that I thought about it, the rocker cover has wells and that grommet should sit in there fairly tightly.

Like the poster said (THANX!), they may possibly be damaged from over tightening. I would look for a slightly longer stud.


How much more top thread do you think you might need?
 
KULTULZ said:
Don't feel silly as I am the one that showed the Ill. The more that I thought about it, the rocker cover has wells and that grommet should sit in there fairly tightly.

Like the poster said (THANX!), they may possibly be damaged from over tightening. I would look for a slightly longer stud.


How much more top thread do you think you might need?
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It would take at least 1/4 inch more.
When I put the valve cover on ,and the grommet (on top of ) the valve cover ,the stud is even with the top of the grommet. I still need to put the chrome washer on, and the thread the acorn nut on at least a thread or two in order to not strip the stud, or the acorn nut.
 
Study the chart - https://www.mcmaster.com/double-end-threaded-studs/setup-studs-5/

... and see what sizes you need. Then we can search further.

In the FORD MPC, it calls for a retaining nut (acorn style for the BIRD I presume) and a lock-washer. It seems to me that one would want a flat washer under the lock-washer to prevent galling. Maybe figure the additional needed length for a flat washer also.

OEM size is 5/16" x 18 & 5/16" x 24 x 4 1/8" total length (doesn't give thread lengths values). Figure your wanted additional 1/2" on the one side that accepts the rocker cover hold down nut.

Ain't this something? It may be that a large NAPA store has a selection of these studs. They are also used to hold full float axles in heavy truck.
 
Both of my Birds have never been messed with and have the grommets on top. I rebuilt the 56 312 and took those studs out. Thought I must of missed placed them as nothing fit back together. I think with the thicker cork gaskets for the aluminum covers and new grommets are just a bit thicker from the originals, but hard to say as they have been squished for 64 years. I just made new studs about a 1/2 longer as I remember.
 
My '54 Y-block manual shows 6570 on top of the valve cover. That other drawing that shows it beneath the valve cover just doesn't make sense.
 

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Consecrating on this, it seems the replacement rocker cover gaskets are too thick and the grommets are too thick. Many descriptions of having to reduce the thickness of the replacement grommets, especially on the valley pan cover. If you force the cover down to clear the stud, you may cause damage to the rocker cover ($$$) with too much torque. If the stud comes out too long, you may not get the correct torque value on the gasket as the acorn nut may run out of threads (bottoming out) before coming to the correct torque values.
 
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