Crooked head studs

D

denver9

Member
I am in the process of installing a 6.1 high compression head on my 31 Model A. I bought the specially hardened studs and all the appropriate gaskets. After installing all the head studs in the block the head gasket would not fit. The studs appear to be bent or non-concentric. As I turn the studs they appear to rotate in a non-concentric pattern (Bent?)
Is this a common problem? If so what is the proper fix? Bend the studs after assembly? Get another set and hope they are straight?
 
If the stud wobbles as it's screwed in, then the problem is a bent stud.

I've seen holes retapped crooked so the gasket and head don't fit properly, but I haven't seen new bent studs.
 
This sounding like a quality control problem for the studmaker.

Generally threads on high strength bolting is formed by the "thread rolling" process - as in no cutting of metal rather the threads are formed by force which causes the metal grain (and stress) to 'flow' around the curves.

Hardening strengthens the studs and by this they mean "heat treating" (not surface hardening.) This similar to quenching a chisel after forging and then annealing for temper (in the case of said chisel.) But this a process fraught with distortion. VERY hard to keep the metal from moving around in what amounts to a "controlled annealing" process.

Is it possible that you could put the gasket down and thread the studs through it? You might even have to play a game of putting the gasket AND head down and then winding the studs into the holes by the "two nut" method of installation?

Granted this is probably not what you were expecting - and neither would I. You pay good money for product and you expect good results in return. But it may be a product challenge which in today's world is at best difficult to provide.

Other than my dodge above, you may have to send these back to your source and hope for better replacements? If you bought these from any of the mainstream providers they likely would be glad to help. Perhaps if you made your difficulties known they might be able to do some "quality assurance" and give you studs that will work first try.

The mainline three providers are VERY good on things like this. One of these parts houses would likely send you out the best set they have on the shelf immediately and wait on your honesty to send the defective studs back. And they pay the return, of course.

Replacement VW diesel head studs of the high strength sort are of this ilk, and don't seem to have this difficulty. But they run $140 a set and are glued in place with special locktite.

Anyway good luck with this. Let us know how you get past this.

Joe K
 
Many of the holes in the block have been heli-coiled. At first I thought the helicoils were to blame. However, even if the helicoil was installed on an angle the stud should still turn in a concentric manner, not with visible run-out.
I will call the supplier in the morning, they have always been fair in their dealing. Maybe they just got a bad batch?
I just thought maybe someone had already crossed this bridge before. I guess it is good that my case is rare, which points back to bad studs. Thanks for the good replies.
-Denver
 
Denver 9, remove the studs and lay them on a flat surface and roll them. This will tell you if they are true. I have an engine that has a crooked helicoil and I had to bend the stud a little to line up the hole in the head. I also had to put some gasket sealer in the hole to keep the water from leaking up out of the block.
 
I have to tap the studs many times to get the gasket on. This is not unusual. The studs don't have to be off much to make it hard to install the gasket. If more than 2 are off the whole gasket will be off. I just use a long 1/2" round brass drift to spring them to fit. Normally it only takes a light hit to move the stud and if 3 or more are off it will only take slight adjustments on each. I have heard of using a 1' piece of pipe that fits over the stud snugly to bend them slightly. If the stud is off drastically you have a bad hole but this is more often than not, only one hole.
 
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Most likely a poor job of threading the studs. The stud was not running true when it was threaded. It does not matter if it was rolled or cut thread. They still have to run true. Just another example of the poor workmanship we have to deal with. It is just as easy to make parts right, you just have to pay attention to detail.

Rolled threads are stronger than cut threads, not sure which ones you have. If rolled the dia where the thread is will be turned smaller for the rolled thread. Cut treads would be the same size as the rest of the stud.
 
I often leave the studs about a 1/4 turn out from tight, this allows them to move a bit when installing the gasket and head.
 
Thanks for all the good input. The studs are the hardened type from Snyder's. I talked to the main guy there this morning. He said that since the studs are hardened (Grade 8) that bending them was out of the question. He also said that they use them every day in their shop with no problem. He also said they routinely turn the studs a half turn or so to alleviate the problem, which to me verifies that there is a run-out problem. He is sending me a new set out to try.
I am tempted to re-install the old, non hardened studs. I bought the new ones because they are guaranteed not to stretch and cause a gasket leak.
-Denver
 
Hi Denver,

In learning things from very older full time trained mechanics born at the turn of the 20th century, who used high compression Police B heads often since the 1930's, they installed same with regular Ford studs with about 55 foot pounds of compression as opposed to the modern religion of providing hardened studs with 65 foot pounds.

Heads & block were "flat" at gasket surface & remained "flat" because in their ancient religion, one never removed a head when hot or even warm which warps same a few thousanths of an inch, & one followed head tightening sequence at about 15 foot pound intervals so as not to place torsional stress on the level head. Overtightening heads meant warped tops of blocks at thin critical block points.

Appears you may have helicoils provided by a novice who just did not know how to maintain 90 degrees on studs & had no idea of how to use an existing head to center newly tapped studs.

If it were mine, I would not hesitate to:

1. First lay the head gasket on the block, insert studs & screw studs in only about 3/4 turn to see if existing stud hole positions are centered & tolerable for fitting a new head gasket or "your" head; and if so,

2. Insure that head & block are "flat", & if not, have same milled "flat", or do what I witnessed & did years ago: Carefully flatened the head & block with my 30" long x 2-1/2" wide blacksmith's file. Provide same motion as using a hand plane to fit (2) planks together with a "straight" line for a watertight boat bottom joint , i.e., start file with light pressure on front & end file movement with light pressure on back to maintain a "straight" line -- just another unwritten lost art from the last century learned from craftsmen who did everything with hand tools in lieu of digital power tools.

3. If every thing checks out thus far, install new non-hardened studs, only hand tighten same with lots of anti-seize on threads, place nut on stud, & carefully tap each stud until 90 degrees is obtained in "all" directions. Carefully check tops of studs occasionally with new head gasket.

4. Install head & do not exceed 55 foot pounds.

5. Last high compression head I installed has the new silicone gasket with only 55 foot pounds of compression & it has not leaked in three (3) years. Before that we used head gaskets with copper on both sides with Perrmatex No. 2 non-hardening gasket sealant which was readily available & known to trained mechanics in the 1930's.

6. Not trying to fight the religion on head installation currently preached today, but just relating different past experiences which may help if one has:

a) A "flat" joint on both sides of the head gasket.

b) A totally screwed up helicoil installation that possibly can be corrected by slightly bending regular head studs as opposed to hauling the block off to the dump.

Hope this helps.
 
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Hi Denver,

Noticed your contemplation of maybe using your existing studs.

Another point is that Model A heads were removed often not only because of no air filter, no oil filter, but also sandy streets & dusty rural highways everywhere; hence, during early years engines went about 8 to 10 thousand miles before embarrassing exhaust smoke became intolerable.

Another part of the ancient religion of ancient trained mechanics was to use new "unstretched" studs & new nuts every time the head was changed to avoid exceeding their stress level, thus reducing breaking of studs.

Hope this helps.
 
DENVER,
Had the same problem yesterday, also got studs from Snyders. They are junk China crap!!!!! I threw those studs in the creek.
 
I had the same problem with my Snyder studs. (And I like Snyders) They are not concentric. Had to back off/screw in to get them centered. No, the studs were not bent. Kinda like rolling an egg end over end!
 
James is right, I have never replaced head studs yet in a block that you don't have to tweak the studs.

Start with the head gasket and get the two front goose neck studs right first, and then hold the gasket to the top of the bolts, and tweak the ones that will bind.

When your done, the gasket should drop to the block surface with little, or no resistance.

If you try to put on a head gasket on with the studs out of alignment, you will also have trouble with the head.

It should slip on also with no resistance. I have seen guys pound them down with a lead hammer, when used a while, they are real tuff to get off again.
 
"If you try to put on a head gasket on with the studs out of alignment, you will also have trouble with the head."

Ya, and then try to get that head off someday down the road....
 
I always use a small carpenter's square to ensure that the studs are at 90 degrees to the head. Makes getting the gasket and head on much easier.
 
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