Closed chambered head bolts

It depends what bolts you have. If they are modern replacement and Torque to Yield then the correct answer is they are single use as they are torqued beyond their spring back point and permanently stretched the first time you use them.

OEM bolts should be okay for reuse, but give them a thorough inspection, paying particular attention to any distress in the threads near where they would tighten in the block.

you want my honest opinion ? Once used ... REPLACE ... you'll be sorry if you don't

How much do the screws cost and how much does a new head gasket, head refacing and labor cost to replace it? You have your answer!

Appreciate the reply

There is no limit on the original Ford head bolts. If in doubt go to the ARP head bolts but it isn't really necessary.

On condition of being certain that during the 50 years of life of the car, no mechanic has tightened these screws with his biceps as any measuring instrument and has not exceeded their elastic limit.

A set of screws costs less than $100.

A couple of years ago I reinstalled the heads on my Euro Pantera with a new set of ARP head bolts after they had a valve job and the bolts worked great.  After that I had to pull the heads two more times to fix some problems.  During the last reinstall I could tell that the bolts are pretty much done and will get a new set of bolts if I have to pull the heads again.

@stevebuchanan posted:

.....  During the last reinstall I could tell that the bolts are pretty much done and will get a new set of bolts if I have to pull the heads again.

was Your indication they were "done", increased head rotation to reach set torque?   or necking at the top threaded section?

I have done more then a few rebuilds in my time. The bolts that I have had the least issues with are the original equipment Ford supplied bolts.

If someone is in the situation of tearing down a lot, it is just logical to predict that something is going to get to the point that it should be considered worn out?

The flanged grade 8 head bolts that Ford originally used are at a level of, or better then the ARP's.

The amount of torque applied is not to a point where you need to measure bolt stretch. Much of that is going to be absorbed in the compression of the head gaskets used.

If you get to the point of stretching the bolts, then you had better start looking at stretching the block. For even a serious vintage road racer, that simply isn't a necessary consideration.

At this point, this discussion is simply an over reaction to "a little knowledge is dangerous".

The only way to be certain that a screw has not exceeded its elastic limit is to measure it as precisely as possible with a micrometer when it is new with an accuracy of a few hundredths of a mm, carefully note this length and check when it is dismantled again the length has not increased? Everything else is just speculation that has no place in a technical discussion.
Now, as almost no one does this (personally I only do it for connecting rod and crankshaft bearing screws), especially on a 50 years old car, I no longer take the risk of refitting screws which I don't know life to save less than $100. I did this on the first engines I rebuilt a long time ago when I was young, inexperienced and had little money........ until I destroyed an engine because of a screw that broke.

I am of course only talking about the main engine screws which support significant forces, not the screws which hold the oil pan or the cylinder head covers or.....

But everyone does as they want their knowledge, their experience and their means.

@Sonas posted:

How often can I use the same Head Bolts? On my 351c? Closed chambered heads.

...FOREVER!!!

In My Experience, the Thead in the Block, will strip-out before the Bolt ever Fails. If the Bolt is Not up to par...You'll Know It! Use a High Quality Torque Wrench. 90 Ft/Lbs Is NOT Enough!! You Will be Blowing Head Gaskets, as Soon as You Pull Higher Revs!

I'd Go to ARP Head Studs, it's good Insurance. Head BOLTS, Confirmed...BOSS 351 Iron Heads on a Iron Block 125 Ft/Lbs, by the Manual. The ARP Techs say, on their Studs, "135 Ft/Lbs!!" and that's on a FINE Thread, NUT! You want to Talk Block Stretch....Studs GO DEEPER!! Installed 'Snug', and use a Sealant, and Take Care, Not to Break Into the Water Jacket! And NEVER!, Bolts on a Aluminum Block!!

MJ

The threads in the block are often overlooked. Make sure that you run a tap through them, clean the threads on the bolts and use a thread assembly lube.

Studs can be difficult to use on a Pantera because of the difficulty of raising the head high enough to clear the top of the studs.

Ford used a special "Reintz" head gasket on the Boss 351 because of the additional torque used on the head bolts, but they are the same head bolts, not special ones..

Many of the Cleveland race engines that I have seen over the years and back in the day were using head studs, It certainly won't hurt to convert to them or use ARP bolts, but generally speaking the Ford head bolts have never had issues.

WRONG!!! Never run a Tap down Threaded Bores! No Two Taps cut the Same. A second Tap will remove MORE Metal and make the Threads LOOSER!!

To Clean the Threads out from debris, take a Sacrificial Bolt and Grind 'Teeth' Into the Nose, and use that to clean out the Bore and Threads. With a 'Different Tap', Once Loosened the Threads will Be Forever Sloppy! "Listen to Me Now, Or Believe Me Later".

...I used a 'Second' Tap to clean-out Block Threads, ONCE, Decades Ago, and Regretted It Ever Since! The Bores were 'Sloppy' Forever! Never Again! It was a 400 Pontiac.

If You havn't already 'RE-Tapped' the Threads...Take a Bolt, screw it down one inch and try to wiggle it, for Play. Tight? Great! Leave it that way! Clean it with a Bolt, Only. Bolts as Critical as 'Head-Bolts', You want them as Tight as Possible!!

MJ

...'Thinned' Threads are Weak Threads. And are More Prone to Stripping Out. You would Realize this, when You Torque Your BOSS Heads to 125 Ft/Lb!! Rip Them Right Out! That's why Most DIY'Rs Stop at 90!

P.S. NO Assembly 'Lube'. The Bolt will Rotate Too Easy and never Torque UP. You'll Keep Going and Strip the Threads. Sealant Only at the Bottom of the Bore. Bolts and Studs Install DRY! And My Heads Clear The Studs Just Fine...But I have The Arms for It, and 6'6" Leaning way in over the Fender. Just have to Move the Pressure Bottle. And Last, Remember...NO Belt Buckles, NO Zippers and NO Levi Rivets!! Even when using a Fender Blanket.

Using a tap, mine have always remained "snug".

In comparing clearances of known bolts, the numbers that I have seen on clearances is approximately .007" on hardware store, off the shelf bolts and .003" on ARP bolts. The ARP bolts therfore are made to better tolerances.

Good Ford bolts are around the ARP number. Maybe +.0005".

In any case you need to clean out the threads in the block. They will often have remnants of thread locker of some kind in the bore. How you do that is up to you.

You can always start checking od's on the taps. You for sure do not want to start repairing threads in the block.

@marlinjack posted:

WRONG!!! Never run a Tap down Threaded Bores! No Two Taps cut the Same. A second Tap will remove MORE Metal and make the Threads LOOSER!!

To Clean the Threads out from debris, take a Sacrificial Bolt and Grind 'Teeth' Into the Nose, and use that to clean out the Bore and Threads. With a 'Different Tap', Once Loosened the Threads will Be Forever Sloppy! "Listen to Me Now, Or Believe Me Later".

...I used a 'Second' Tap to clean-out Block Threads, ONCE, Decades Ago, and Regretted It Ever Since! The Bores were 'Sloppy' Forever! Never Again! It was a 400 Pontiac.

If You havn't already 'RE-Tapped' the Threads...Take a Bolt, screw it down one inch and try to wiggle it, for Play. Tight? Great! Leave it that way! Clean it with a Bolt, Only. Bolts as Critical as 'Head-Bolts', You want them as Tight as Possible!!

MJ

...'Thinned' Threads are Weak Threads. And are More Prone to Stripping Out. You would Realize this, when You Torque Your BOSS Heads to 125 Ft/Lb!! Rip Them Right Out! That's why Most DIY'Rs Stop at 90!

P.S. Sorry Doug! NO Assembly 'Lube'. The Bolt will Rotate Too Easy and never Torque UP. You'll Keep Going and Strip the Threads. Sealant Only at the Bottom of the Bore. Bolts and Studs Install DRY! And My Heads Clear The Studs Just Fine...But I have The Arms for It, and 6'6" Leaning way in over the Fender. Just have to Move the Pressure Bottle. And Last, Remember...NO Belt Buckles, NO Zippers and NO Levi Rivets!! Even when using a Fender Blanket.

Completely agree with you about cleaning the threads, never a tap.

On the other hand, for lubrication, I would not be so categorical, it depends on how the tightening torque was determined by the manufacturer. ARP for example clearly specifies that the torques they indicate are to be applied with their super lubricant.

The objective of tightening is to apply a tensile force to the screw, an effort sufficient to obtain a solid assembly but corresponding to a stress lower than the elastic limit.

The torque corresponding to this effort was calculated as a function of the slope of the thread and the coefficient of friction between the threads.
If the coefficient of friction used takes into account lubrication and we do not lubricate, the force applied will be less than that desired and the assembly will not be sufficiently strong. Conversely, if dry tightening is planned and lubrication is used, the force will be greater than expected and risks exceeding the elastic limit.

There is therefore no general rule, you must follow the recommendations of the manufacturer who made the calculations.

...You are correct! ARP Recommended THEIR Lube be used UNDER the NUT (NOT on the Threads) as in the case of their Studs**. I presume a Drop of Lube under the BOLT Head wouldn't hurt. But, 'Assembly' Lube is for Camshafts and Rockers to Valves.

And, It's Not so much the Diameter of the Tap as it is...NO two Taps are EXACTLY* the Same, on the FLANKS of the TEETH! And There Exist, at Least, 3 Mechanical Types of Taps...Tapered Tap, Plug Tap, and a Bottom Tap. Which tap did FORD use? And which Tap Did You Use??

Use a 'Sharpened' Bolt, to Clean.

*Different Taps? You won't Know this until After you have Ruined Threads. Just in My Experience of Over 50 Years as a Master Machinist. I AM the Master of Threads! I AM the Master Splines. I AM the Master Of Tapers. If Your Bores remained 'Snug'...You were Damn Lucky!! Anybody Else?

** ARP also recommends THEIR studs be Installed 'Hand Tight' with the fingers...nothing More. With a Sealant on the Bottom few threads of the Stud, just in case the Bore gets Cracked into the Water Jacket. I Installed My Studs, with sealant using the 'Jam-Nut' Method, NO Lube On the Threads, A Few Drops Of ARP LUBE Under The NUT ONLY! I 'Snugged' The Studs in with a Very Light Pressure with a Wrench, just to Make sure they were 'In all the Way', and with the Greatest Respect to the Water Jacket! There is a 'Stud Installation' Tool...I Never Needed One. BOLTS Should always have a Sealant on the Bottom few Threads. I Never used a Lubricant on ARP Threads! The Torque is Proofed on the Fine Thread NUT, NOT the Studs Course Threads!! So why would You Lube Those? My Recommendation is, BOLTS INSTALL DRY!!

MJ

I have never been lucky. I just knew what I was doing.

The variance on a bolt is going  to be more then on a tap. The Ford bolts are really very good. I have had more issues with ARP then the Ford although not enough to form a significant negative pattern.

We all learn from our own mistakes. With the amount of mistakes that I have made, I should be a genius by now and yet, I am not? It is a good thing that we share information. It comes from different experiences and shouldn't be arbitrarily dismissed?

I feel like we are a bunch of surgeons debating how to do the sutures?

...Sure Doug! Your a Genius!!

And I'll Leave it There!

You're still My Friend...Hugs and Kisses! LMAO

Marlin

"No Man is as Blind as the Man who WON'T SEE"

You guys are funny!

I reuse the Toyota Head Bolts on my Land Cruiser.

I chase the threads by taking an old head bolt, and using a hacksaw to cut a slightly angled longitudinal groove across the threads.  The groove gives all the “gunk” a black to go as you run the “chaser” in and out.

Rocky

@rocky posted:

You guys are funny!

I reuse the Toyota Head Bolts on my Land Cruiser.

I chase the threads by taking an old head bolt, and using a hacksaw to cut a slightly angled longitudinal groove across the threads.  The groove gives all the “gunk” a black to go as you run the “chaser” in and out.

Rocky

...Right-On Rocky!!! Exactly What I was Talk-n-Bout!!

Thank You

Marlin