Engine: Source for NOS or replacement Champion head bolts (cap screws)?

[Lothar]

They aren't listed in SI's catalogue, at least I can't find them. I couldn't find anything on eBay, either. I find three different part numbers for different length screws (longer screws for battery ground 519141 and spark plug wire bracket 520182), with the main cap screw part # 194459. Anybody out there have a source or a few they can spare?
I would appreciate any help as I have two Champion engines that I'm planning to re-build. I recognize that I shouldn't need to replace a full set, but I suspect that at least a few could be corroded or overtorqued.

Thanks!

[TrickyRick]

Please clarify.

In my mind screws dont have hex heads and are usually not bigger than 1/4".

If you cant get them from an old motor you may have to order them from a performance parts mfgr like ARP.

[jnormanh]

They aren't listed in SI's catalogue, at least I can't find them. I couldn't find anything on eBay, either. I find three different part numbers for different length screws (longer screws for battery ground 519141 and spark plug wire bracket 520182), with the main cap screw part # 194459. Anybody out there have a source or a few they can spare?
I would appreciate any help as I have two Champion engines that I'm planning to re-build. I recognize that I shouldn't need to replace a full set, but I suspect that at least a few could be corroded or overtorqued.

Thanks!

I suppose it's a dumb question, but why can't you just buy generic good quality (grade 8) bolts which are readily available everywhere from Lowe's to Tractor Supply?

[PackardV8]

Please clarify.

In my mind screws dont have hex heads and are usually not bigger than 1/4".

If you cant get them from an old motor you may have to order them from a performance parts mfgr like ARP.

What are the differences between a hex cap screw and a hex bolt?

These terms are often incorrectly used interchangeably. The variations between these fasteners are fairly significant both from a manufacturing perspective and application standpoint. Generally speaking, hex cap screws are used in precise applications like an OEM setting where tight tolerances are required.

Hex bolts are often specified when the mechanical properties are more important than dimensional tolerances, like the construction industry. For example, for fasteners having the same diameter and hex head, SAE J429 Grade 2 is a hex cap screw, whereas ASTM A307-A is a common hex bolt specification.

So yes, on a low-stress application, such as a Champion head bolt, a grade-8 hardware hex bolt would probably work.

But no, a grade-8 hex bolt is not the same as a cap screw.

jack vines

[Skip Lackie]

Thanks Jack. That clarifies my previous (partially correct) understanding.

[rockne10]

That also addresses Rick's question. When a screw is referenced, it is very rarely a "cap screw" but, when the reference is to a "cap screw", it is a particularly unique type of screw.

[Lothar]

Wow, Jack, thanks for your thorough answer of the differences between cap screws and bolts. I mentioned the term cap screw simply because thats the term that the Studebaker parts book uses.
So, to answer my question, you (Jack) concur that grade 8 bolts would be acceptable replacements for Champion head bolts...er, I mean cap screws? If so, can someone give me the lengths of the three different head cap screws used? The service manual tells me to use a 7/16" 14 pitch tap to clean out the holes, but it doesn't give me the specs of the bolts themselves.

[jnormanh]

What are the differences between a hex cap screw and a hex bolt?

These terms are often incorrectly used interchangeably. The variations between these fasteners are fairly significant both from a manufacturing perspective and application standpoint. Generally speaking, hex cap screws are used in precise applications like an OEM setting where tight tolerances are required.

Hex bolts are often specified when the mechanical properties are more important than dimensional tolerances, like the construction industry. For example, for fasteners having the same diameter and hex head, SAE J429 Grade 2 is a hex cap screw, whereas ASTM A307-A is a common hex bolt specification.

So yes, on a low-stress application, such as a Champion head bolt, a grade-8 hardware hex bolt would probably work.

But no, a grade-8 hex bolt is not the same as a cap screw.

jack vines

McMaster-Carr calls all the higher strength bolts "Cap Screws" from grade 8 through 12.9

Grade 8 is rated maximum tensile strength of 150,000 psi, and Grade 9 is rated minimum tensile strength of 180,000 psi, certainly enough for any production engine.

I don't know the dimensions of the head screws in question, but grade 8. 7/16-14 x 4" are $11.57 for a pack of ten. Grade 9 in that size are $3 ea.

http://www.mcmaster.com/#hex-head-cap-screws/=120w4gu

[rockne10]

The service manual tells me to use a 7/16" 14 pitch tap to clean out the holes, but it doesn't give me the specs of the bolts themselves.

Here's where the Chassis Parts Catalog comes in handy. The '53 catalog says 7/16"-14x2 5/16" for the Champion engine part # 194459. You will need to check the appropriate chassis catalog, not service manual, for your application.

[Dan Timberlake]

On some engineering forums Cap Screw vs bolt gets responses similar to "oil" threads here and elsewhere.

There is some evidence that, at some level above water cooler conversations, it would not be wrong to say a bolt is a screw that uses a nut, and a screw is a bolt that is installed in a threaded component, like when securing a cylinder head to a block.
Hence Studebaker's not calling head bolts head bolts, but cap screws.

[Lothar]

Brad
Thanks for finding the screw length for me. I have a chassis parts book, but I didn't think to look there. Since you gave me that tip, I went ahead and I looked it up myself. The "distributor cables bracket" aka spark plug loom to head bracket screw is 7/16" -14 * 2 11/16". Factory torque spec is 46-50 Lb.s for these screws.
Since these screws are non-standard lengths (7/16"-14* 2 5/16" and 7/16"- 14* 2 11/16") I would need to cut standard hardware to length... UNLESS other manufacturers (Chrysler, Ford?) used these same size and length bolts. Does anyone know if there is any chance that they might interchange with a more common application?

[dpson]

Hi John,

I show all three part numbers; 194459, 519141, 520182, in inventory (NOS).

Send me a PM and let me know how many of each you need.

[Lothar]

Great Dan, Thanks!

[garyash]

There are important differences between hex head cap screws and hex head bolts.

Philosophically, a bolt is designed to pass through two or more parts and is secured by a nut on the end, perhaps with a washer and/or lockwasher. The nut gets turned to tighten the assembly and provide the clamping force, and the nuts have smooth faces. The bolt head is allowed to have die marks on the under side, and a washer face is not usually included. The bolt provides non-precision alignment of the parts. Bolts can have an unthreaded body diameter that is greater than the nominal size and a minimum diameter equal to the thread minimum diameter. So, on a 7/16-14 bolt, the maximum body diameter is 0.452" and the minimum is 0.421". The bolt's head height can be from 0.272" to 0.316".

A hex head cap screw is usually (but not necessarily) used to pass through one piece and thread into a piece on the other side. That is, it is secured without a nut. To tighten it, the bolt head must be turned. Hence, a smooth washer face with minimal circular runout is provided under the hex head. The washer face also prevents the hex corners from digging into the surface below it so that tightening torque is controlled. The maximum body diameter of a cap screw is the same as the nominal size and the minimum diameter is only slightly smaller. For a 7/16-14 cap screw, the maximum diameter is 7/16"=0.4375" and the minimum is 0.4305". This provides precision alignment of the parts. The cap screw head height is more tightly controlled, as well, so a 7/16-14 cap screw has a height of 0.272"-0.291". In addition, a small radius is provided on cap screws where the washer face transitions to the body diameter to reduce stress where the head and body join.

Places like Fastenal carry, or can special order for you, cap screws in a wider range of lengths than the big box stores, though you may also find them at "real" auto parts stores.

If you want to get into how bolts work - or not - take a look at http://www.boltscience.com.

[jnormanh]

7/16" -14 * 2 11/16". Factory torque spec is 46-50 Lb.s for these screws.

I see you have found a source for the correct cap screws.

For future reference:


Recommended tightening torque for grade 8, 7/16-14 is 70 ft-lb dry or 50 ft-lb lubed.

That would indicate to me that the factory original cap screws are no stronger than grade 8.

http://www.americanboltcorp.com/tech/techtorque.pdf