8ba head studs

[cuzncletus]

I'm a great believer in studs, both in bottom ends and heads. However, when I read the specs on commercially packaged head studs it seems they're beyond overkill. 170,000 psi tensil strength studs and grade 8 nuts just don't seem to make sense when you're torquing the heads to only 45/50 lbs. I think I can get correct thread studs through a local fastener supply a lot cheaper than the $100 they sell for nationally. I was able to buy all stainless bolts for my last engine at about 1/4 the cost of buying them at one of the big box hardware stores.

Am I missing something here about cylinder pressures or anything else?

[D. Jones]

Since I am building a driver rather than a show piece, I used grade 8 bolts when I built my 59 ab. They cost a fraction of what the Ford suppliers wanted for head bolts and I'm quite sure they are more than strong enough.

[BILL WZOREK]

Hey guys , other's may Chaim in, But I think the thread in the block is a little different then what you get at the big Box store. That is why the Big $$$ for ford correct Head studs & Bolts. Supply & demand.

[rotorwrench]

I'm not sure what FoMoCo specified for fit on studs but my experience with aviation applications has been that they are set up tight. They drive in to a specific torque. If they are loose they are replaced with the next oversize. By oversize I am refering more to stud fit measured in thousandths of an inch. I don't know if FoMoCo ever used this type of application or if oversizes in .003" or larger were ever available or not.

Where a person may run into trouble with less than grade 8 bolts or studs is when you try to remove them after they have been in place for a good bit of time. Some extend into the water jackets a bit and the tips get crusty. A soft bolt or stud would likely snap off when you go to remove them. I've busted my share of bolts & studs off and I know they don't come out as easy as they went in there for sure.

[Bruce Lancaster]

On flatheads with studs (I am not sure about the 8BA type blocks) the threads are a very tight fit spec and the top of the hole in block is countersunk a bit to seat the original stud. With good original block threads and studs the studs will seat vertically and so not fight you when head goes on and will not leak. If a standard fit tap with common class three threads (meaning any normal tap you can buy without serious searching) is run into block, studs will then require sealant and you will have to go through the ritual of pre-assembly to seat the studs straight while your thread goo dries.

[Ronnie]

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What will a stud provide that a head bolt torqued to spec could not provide?

50 lbs torque on a bolt is all that you need with such low compression ratios you won't have any problems whatsoever.

R

[Bruce Lancaster]

I think the actual chief benefit of studs is reduced wear on block threads...as with all production engines, deck is thinner than ideal and the threads have been marinating in dirty water for 60 odd years as well. Flatheads need routine re-checking of tightness while they run in, and aluminum heads add to the need. With studs all the real violence is happening on a replaceable part upstairs. And of course if the studs are properly sealed and set, they stay that way...you aren't going to disrupt a shaky sealing situation by turning a bolt.

[JM 35 Sedan]

I prefer using studs over bolts on these flathead engines for all the reasons that Bruce has given. I like to clean the threads in the deck (not by using a tap) and then set the studs in place with a good non hardening sealer on the threads. I prefer the fine threads on the studs/nuts for better control of torquing the nuts. I also like the final appearance of the studs/nuts over the head of a bolt. If you have any weak or otherwise questionable threaded holes in the decks it is much more likely that you will strip these threads while torquing bolts. It is also more likely to raise the first threads above the deck surface when using bolts. I am not concerned about saving a few bucks on head studs or bolts when it comes to building a FH engine if I already have many bucks invested in machining, components and assembly labor.

[GOSFAST]

For the guys who believe in re-torquing the head fasteners, one definite advantage to studs is once you've got the unit broken in and have no leaks you can safely back off the nuts from the studs and do the re-torque. This becomes questionable with bolts unless you reseal the bolts again one at a time.

The chances are you will not lose the "seal" on the deck threads with studs! The stud should stay in position. Newer ARP studs come with an allen head end if it were necessary to "hold" the studs while loosening the nuts!

Also all correct about the deck threads not liking the bolts being taken in and out/loosened that many times.

Thanks, Gary in N.Y.

P.S. In any event, on any fresh builds, do not install any type anti-freeze until the unit is "broken-in" and totally finished. The anti-freeze will slow any leaks from stopping on their own. 100% fresh water only during break-in. We are in a more fortunate position to be able to use the dyno for running/testing.

[Bluebell]

On the subject of studs .
The stud has a fine thread at the top, and a course thread into the block.
The stud "seats" into the counter sink in the deck. They are not wrung up tight. I think rumbleseat said no more than 10 ft/lb, to seat them. and that you should be able to run them in with your fingers, once you have cleaned the threads out. He does not recommend running a tap through them.
The stud should not move at all in the course thread when the head is being torqued down, only the fine threaded nut should move on the shallow ramp of the thread at the top end of the stud. The idea of the high tensile stud is that it never stretches in the thread of the deck, which means the load is spread over the entire length of the tread. If you like, the high strength stud is supporting the weaker cast iron thread in the block. This makes for a much more reliable engine block, a known weak area, of the Ford flathead v8.
Is that useful?

[Ross F-1]

Originally Posted by Bluebell

...The idea of the high tensile stud is that it never stretches in the thread of the deck, which means the load is spread over the entire length of the tread. If you like, the high strength stud is supporting the weaker cast iron thread in the block. This makes for a much more reliable engine block, a known weak area, of the Ford flathead v8.
Is that useful?

Sorry, that is just not true. There can't be tension in part of the stud but not the rest.

What is different about a stud is that there are no torsional forces to speak of in the stud as the nut is tightened, it is in pure tension. With a bolt you have the entire length of the bolt twisting as you crank the head of the bolt, so you get some spring-back when you let go of the torque wrench. Friction in the threads also muddies the torque reading.

In all but the very tightest class of threads, no more than 3 threads are carrying the load.

[Bluebell]

Sorry Ross, Which bit is not true? So can try again, to be more clear.

[Ross F-1]

The idea of the high tensile stud is that it never stretches in the thread of the deck

The threads in the block do stretch on a stud, but they don't have to rotate as they are picking up tension.

[Bluebell]

Sorry Ross, Which bit is not true? So can try again, to be more clear.
Of course the stud is under tension.

[Ol' Ron]

I think studs are over kill, so did Ford in 49. Never used them in my street engines. NOw are they better? yes, but at 45 ft lbs, just an added expense in an already too expensive hobby.

[JM 35 Sedan]

I believe Ford changed from the use of head studs to bolts as a material, labor and service cost savings. Also an obvious savings for professional and amateur engine rebuilders.
After Henry Ford passed away many things began changing at the Ford Motor Company, some were not in the best interest of Ford nor their customers.

[Bruce Lancaster]

Ford hired an army of beancounters from GM as soon as Henry was in the ground, and lots of nice but expensive features started going away starting during 1947...

[John R]

Originally Posted by Ol' Ron

I think studs are over kill, so did Ford in 49. Never used them in my street engines. NOw are they better? yes, but at 45 ft lbs, just an added expense in an already too expensive hobby.

2x what Ron said.

[Bluebell]

Bishops book said something to the effect of "you might need to go through eight blocks to find a good one".
At home, that could be $400 to $800 each.
They might be common in the good old US of A, but I wouldn't be going to all the trouble of a full rebuild to risk pulling threads, at the late stage of trying to torque a head.
I hate doing things twice. with mine, I'll be playing it safe.
Just my opinion.

[russcc]

What did we learn from this great post. More seem to prefer studs for thread & deck life. Don't run a tap into a head stud thread, it's a different class of thread, and will weaken an all ready marginal system. I learned a lot, and just this afternoon replaced some missing studs in a 60 lock deck. Maybe I should have not run the studs in to the block so tight.