Head Studs

[steammech50]

Had too change head gasket in my 31,found head studs not screwed down too the shoulder of the stud,some were quite loose in the hole.Should these be screwed in tight ? This was a fresh rebuild,mabey wanted to keep all studs same height ?Thanks fer the help !

[edmondclinton]

Originally Posted by steammech50

Had too change head gasket in my 31,found head studs not screwed down too the shoulder of the stud,some were quite loose in the hole.Should these be screwed in tight ? This was a fresh rebuild,mabey wanted to keep all studs same height ?Thanks fer the help !

Studs should be screwed all the way in to their shoulder and screwed snug but not tight.

There should be no problem with the height of the studs if they are original or a correctly made repo.

[George Miller]

Originally Posted by edmondclinton

Studs should be screwed all the way in to their shoulder and screwed snug but not tight.

There should be no problem with the height of the studs if they are original or a correctly made repo.

I disagree, they do not need to be in tight. That will cock them and you might have trouble getting the head on and off.

In the cylinder business we put them in until they were the right length. With long tie rods you did have to allow for stretch in the rods. They had to be thread in at least 1 1/2 there dia. as a general rule, but that depends on type of material and a lot of other things.

We made cylinders up to 24" bore, and they were high pressure hydraulic cylinders.

[Kahuna]

If you look closely at a cylinder block, you will notice a chamfer about 45 degrees on each stud hole (stock block, not surfaced). Each stud has a corresponding chamfer. Studs should be installed snug (some recommend 5-10 # torque).
In this fashion, no cocking of the studs will occur, thus, no difficulty in head removal.
If the block has been surfaced for whatevewr reason, each hole should again be chamfered.

[edmondclinton]

Originally Posted by George Miller

I disagree, they do not need to be in tight. That will cock them and you might have trouble getting the head on and off.

In the cylinder business we put them in until they were the right length. With long tie rods you did have to allow for stretch in the rods. They had to be thread in at least 1 1/2 there dia. as a general rule, but that depends on type of material and a lot of other things.

We made cylinders up to 24" bore, and they were high pressure hydraulic cylinders.

If you'll read what I said, I did not say tight. I said snug. Snug, by my definition, is just a little tighter than finger tight but not tight as in turned tight with a big wrench. Plus, if the studs are straight there's no reason for them to cock.

The bottom end of the Model A stud that screws into the block is made to a length of 3/4". The stud should be screwed all the way in to utilize the full strength of the 3/4 inch worth of threads in the block, as designed by Ford.

The original stud length of 3 1/2" for 11 studs, 3 11/16" for the ignition stud (on most Model A's) and 5 3/4" for the long front two are all the correct length so when screwed in to the shoulder, the height is correct to accommodate the thickness of the original gasket and the thickness of the original cylinder head plus the thickness of the original nut, with a little left over to protrude above the nut.

[George Miller]

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Originally Posted by edmondclinton

If you'll read what I said, I did not say tight. I said snug. Snug, by my definition, is just a little tighter than finger tight but not tight as in turned tight with a big wrench. Plus, if the studs are straight there's no reason for them to cock.

The bottom end of the Model A stud that screws into the block is made to a length of 3/4". The stud should be screwed all the way in to utilize the full strength of the 3/4 inch worth of threads in the block, as designed by Ford.

The original stud length of 3 1/2" for 11 studs, 3 11/16" for the ignition stud (on most Model A's) and 5 3/4" for the long front two are all the correct length so when screwed in to the shoulder, the height is correct to accommodate the thickness of the original gasket and the thickness of the original cylinder head plus the thickness of the original nut, with a little left over to protrude above the nut.

What ever you say, but they should be put in to the proper length. If you check some of the studs to day I think you will find they are a little short.

[George Miller]

if the studs are straight there's no reason for them to cock.

I have seen it many times. Some one re taps the treads in the block. You have lets say .002 clearance. You screw the stud in tight, it cocks the stud when it runs out of thread .002 at one 1/2 ". So lets say the stud is above the block 3" that means the top of the stud is off .012 or those who do not know just about a 1/64. Now do the rest of the studs they are leaning ever direction. You will end up with the tops of the studs off .024 you will have to force the gasket and head on.

There is no reason the screw them in any more than they were designed for. But do them any way you please. It is your car.

[barry022]

Originally Posted by 1930 coupe

I put permatex on the thread before putting it in the block, that will keep out the water and after it sets a couple of days it will hold the stud in the block but it can still be removed if needed.

Based on your comment, the stud holes are tapped into the water jacket, correct?

[larrys40]

George ,
I agree with you on them. I have put onany but i think that guys like herm konke , james , and rich falucca and j &m could shed more experience on it than most of us . I put a head I yesterday and have one stud nut with a few threads left without stud . I wish i had screwd it back out a thread ir two . I have done them both ways and have never had a problem
I do think with them in hand tight you will probably never have a hard time getting them out if need be . Not so sure if tighter . Some folks just have a tendency to argue.
When you think about it compared to the later 8ba flatheads which had bolts its the tension of the threads to bolt to torque that are critical . The bolt never bottoms out
Larry Shepard

[Bob Bidonde]

The joint of the cylinder head to the block is in tension. Therefore the strength of each stud-to-block connection is determined by the number of threads engaged. Tightness of the studs in the block is not a concern because the cylinder head nuts when torqued will develop the a preload.

[steammech50]

Thanks for the input,now just have too decide which way to go !

[James Rogers]

Originally Posted by edmondclinton

Studs should be screwed all the way in to their shoulder and screwed snug but not tight.

There should be no problem with the height of the studs if they are original or a correctly made repo.

There is no such thing as "correct" head studs and running them down to the shoulder WILL make them different heights. This is particularly true if any of the holes have been drilled in or had thread replacement.

[James Rogers]

Listen to George. My suggestion would be to use some permatex #2 and thread them in to 2 3/4" and let them sit overnight to tighten and put the head on. The #8 stud can be put in to the bottom and the front 2 that hold the water outlet are down snug.

[edmondclinton]

Originally Posted by George Miller

If you check some of the studs to day I think you will find they are a little short.

Yes, that's true if they are not made to the original specifications.

[edmondclinton]

Originally Posted by George Miller

if the studs are straight there's no reason for them to cock.

I have seen it many times. Some one re taps the treads in the block. You have lets say .002 clearance. You screw the stud in tight, it cocks the stud when it runs out of thread .002 at one 1/2 ". So lets say the stud is above the block 3" that means the top of the stud is off .012 or those who do not know just about a 1/64. Now do the rest of the studs they are leaning ever direction. You will end up with the tops of the studs off .024 you will have to force the gasket and head on.

There is no reason the screw them in any more than they were designed for. But do them any way you please. It is your car.

I see your point. But that does not apply to blocks that have not had hardware store taps screwed into them or blocks that still have good holes and threads.

In addition, many of the repo studs available from the vendors are often not completely straight. Just roll them across a flat table and watch them. The reason many are slightly bent is they are warped by the heat treatment process they receive. They are literally shoveled in. to the oven.

I have a fixture that I use to straighten them. Some people will bump them with hammers with them screwed into the block. That method makes me nervous.

Now if a person wants guaranteed straight studs then buy some for ARP. They are straightened and threaded AFTER they are heat treated.

[edmondclinton]

Originally Posted by James Rogers

There is no such thing as "correct" head studs and running them down to the shoulder WILL make them different heights. This is particularly true if any of the holes have been drilled in or had thread replacement.

Sorry, that's not true. If the studs are original or are made to Henry's original specs and the holes and threads are unmolested, studs of the same length will be the same height above the block after being screwed in to utilize the 3/4" length of threaded area at the base of the stud.

[CarlG]

Originally Posted by edmondclinton

...Now if a person wants guaranteed straight studs then buy some for ARP. They are straightened and threaded AFTER they are heat treated.

That is what I use.

[edmondclinton]

Originally Posted by Bob Bidonde

The joint of the cylinder head to the block is in tension. Therefore the strength of each stud-to-block connection is determined by the number of threads engaged. Tightness of the studs in the block is not a concern because the cylinder head nuts when torqued will develop the a preload.

Yes, the number of threads engaged is the strength.

With studs not screwed all the way in, I have seen studs turn slightly with the nut when torqueing to the final amounts. ARP recommends finger tight on their instructions for studs used with flat heads. I like to put a tiny bit extra with a pair of pliers gripping a rag around the base of the stud (with emphasis on the word tiny).

[MrBruce]

My dad build Model A's and flatheads all his career and the engines for our cars we used Chevy main bolts for my B and sure is nice. I don't have to mess with the studs and the heads come off nice. Doesn't work if your showing the car but for drivers it looks nice.

[James Rogers]

Originally Posted by edmondclinton

Sorry, that's not true. If the studs are original or are made to Henry's original specs and the holes and threads are unmolested, studs of the same length will be the same height above the block after being screwed in to utilize the 3/4" length of threaded area at the base of the stud.

My point is, none of the current suppliers of Model A parts stock or sell any studs of the correct size. I know there are studs somewhere in the world that are correct but most don't have that information or can afford those. I also believe I stated that the holes could not be molested for any kind of stud to work like you say.