Ol´Ron,Pete,Gosfast and other experts ....

[vilanar]

Hi guys,
There has been this conversation about head bolt vs. studs.
Most of you prefer Ford bolts.
What I have missed is , the reason why ?
Besides that Ford bolts are great quality...
Doesn´t studs usually clamp better ?

And thank you all who share your knowledge here.

Ari

[Kahuna]

Studs

[rockfla]

At face value, studs with Heavy Pattern Nuts (Which is what the Early Flat Heads used) has more clamping force and higher torque values than comparable diameter hex bolts. Material and heat treating play a big roll as well as to torque and clamping pressures. Also (Generally speaking) the Average commercial bolt is a Finished head NOT a Heavy head so your loosing surface area contact there as well.

[51 MERC-CT]

Gee, I wonder if the studs were so much better, why from '48 on, to my knowledge did all flatheads as well as later OHV engines successfully use bolts?

[GOSFAST]

Originally Posted by 51 MERC-CT

Gee, I wonder if the studs were so much better, why from '48 on, to my knowledge did all flatheads as well as later OHV engines successfully use bolts?

Cost a hell of a lot more to make a stud, nut, and washer than a single bolt!! This is the crux of the matter!

The clamping force is determined by the fastener mfr. There are head bolts from vendors like ARP that will clamp much tighter than many aftermarket studs/nuts. On a Flathead this is really a "moot" point so to speak!

(Add) I really appreciate being included in that group above in the title!! Some good company there.

Thanks, Gary in N.Y.

P.S. There is one advantage to studs over bolts, if you seal the studs in position during assembly chances are they will NOT come loose at the bottoms while re-torquing, technically only the nut and washer should see the movement!

[jetmek]

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bolts are probably cheaper to produce. Studs provide better/more accurate tightening but Id rather use bolts especially with aluminum heads.

[Ken/Alabama]

When using cast iron heads I like the studs better . But when using aluminum heads I prefer bolts, makes it easier to get the heads off without damaging the heads should the occasion ever arise.

[rockfla]

To Gosfast point, the torque values used on the flathead heads, your not in the range where its critical with either one as long as the material is quenched to handle the heat range/cycles.

[russcc]

Vern Tardel has built a few flatheads, and seems to prefer the head bolt as I read in Ron & Vern's new book. Makes sense that with the flatheads low torque values, and w/almn heads. I would think that if you used original Ford head bolts from the era, if they are long enough, you would be good to go.

[40 Deluxe]

At what point will too much torque on the bolts distort the deck surface?

[34PKUP]

Originally Posted by 40 Deluxe

At what point will too much torque on the bolts distort the deck surface?

Probably at the same point as when using studs.

[Cheaterpete]

I like bolts, with 24 good bolts, no need of studs IMO

[JWL]

I am not one of the experts but I do have an opinion---If the stud and bolt are each stretched to the same value and are of similar elasticity there is NO DIFFERENCE in clamping force. The advantage studs provide is in the reduction of thread wear and easy on and off alignment for those engines requiring frequent maintenance.

If torque is applied above 50 lbs. (45 is better) the deck is moving up to the head in various locations.

[rockfla]

IMO
I have been selling commercial/industrial fasteners now for the better part of 30 years, the long and the short here is that for the torque value used on the Flathead Heads (as long as the correct material is used) either the stud & Nut or a bolt will do what is asked of it to do. BUT....In "MOST" instances, a bolt uses a Finished pattern head which is one wrench size smaller than a Heavy Pattern Nut (Which is what the Early Flat Heads used) and even in equal materials I think that having the extra bearing surface of a heavy nut spreads the load overall a greater surface for more equal clamping load across a surface. Case in point, Pipe Flanges.....Use Heavy pattern Nuts to spread more equal pressure on the Pipe Gasket for better sealability. Just my .02 cents.

[rockfla]

And I preface my above statements based on ignorance of what type or form of bolt an 8BA uses.

[scooder]

John,
I have to disagree with your first point, you are an expert, plain and simple!
In theory studs are better, a lot of the super dooper race stuff uses studs. The big blown hemis for instance, with thousands of horse power.
On a flathead? Don't make a difference really, other than ease of removing heads, the bolts arnt taxed at all.
So down to choice in my opinion.
Martin.

[rockfla]

Scooder
When looking at the torque values and clamp loads for like materials that are commercially available to the general public, you are wrong......the clamp load values and toque values are virtually identical. Case in point is I use B7 material which is a Heat treated Grd 5 material (Available in both studs and Hex Head Bolts) and one can compare that to a B7 Hex Head Bolt and when you do......say for 7/16 diameter the value is as follows bolt- 11,150 stud-11,162 clamp load value.

[rockfla]

Two things to your point with regard to the Top Fuel Boys
I would submit that they use studs specifically designed and treated for their specific use and most of all they use studs for quickness of alignment and for just sheer quickness. Having to try and hold those heads in place and align bolts would be a pure pain in the ass and moving and sliding that head around while trying to do so would play hell on the head gaskets.

[flatheadmurre]

Studs have a lot of good aspects as you can move wear from the block to the stud and youre able to get a better controlled seal between block and stud.
Load and clamping force is a non issue in this case.
Start counting a modern high performance motors numbers of headbolts !
Think it in this case is down to the taste of the wrencher.
A flanged bolt will do as well or better then the large nut distributing load.

[flat 39]

fwiw. A higher clamp load can be obtained with a stud of equal material than a bolt. When installing a bolt there is torsional stress in addition to tensional stress. The stud only sees tensional stress so a higher torque value can be applied to the nut. This may be of value in high stressed racing engines, but of no value in flatheads do to deforming the thin topdeck at the high torque numbers.