Bolts for engine stand
- Thread starter '29 Pickup
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Bruce of MN
Well-known member
'29 Pickup
Member
Thanks for that.
Would that be UNC, UNF or BSW?
Would that be UNC, UNF or BSW?
jack wingard
Senior Member
pretty sure all the info given in the link is all you need to order bolts. 7/16" - 14, the 14 indicates, 14 threads per inch
1" block depth should work, the pic shows washers. just don't bottom the bolts out
1" block depth should work, the pic shows washers. just don't bottom the bolts out
'29 Pickup
Member
Thanks....please excuse my ignorance....never got taught imperial at school....it was like it had never happened.
Looking at a chart for threads....UNC and BSW both are 14 threads per inch @ 7/16 and it's unclear to me when the US changed from the British standard.
I'm assuming these bolts are UNC
.
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johnneilson
Well-known member
The UNC and BSW refer to the thread form or shape of the thread
Not sure when Us standard came to be both listed in 1919 machinery handbook
J
Not sure when Us standard came to be both listed in 1919 machinery handbook
J
'29 Pickup
Member
I read that it mostly happened when bolts went from iron to steel, with some exceptions.
Phil Brown
Well-known member
7/16 - 14 is considered a coarse thread bolt, might say NC for national coarse. The one that you need
A 7/16 - 20 would be what would be the fine thread of that size and might say NF for national fine thread
A 7/16 - 20 would be what would be the fine thread of that size and might say NF for national fine thread
katy
Well-known member
UNC and BSW have different thread angles, they're not interchangeable.
Bruce of MN
Well-known member
The OP should get a thread chart like this or another:
https://www.machiningdoctor.com/charts/unified-inch-threads-charts/
https://www.machiningdoctor.com/charts/unified-inch-threads-charts/
'29 Pickup
Member
Are the bolts on the Model A mostly UNC or are they a mix of UNC and UNF?
Phil Brown
Well-known member
A mix of both
Look a a head stud, fine thread on one end and coarse on the other end
updraught
Well-known member
Yes. It's a different world over there. They will tell you they cannot give up the 10 yard line or something.
A mix of both
Look a a head stud, fine thread on one end and coarse on the other end
Typically coarse when screwing into a casting, fine when screwing into forgings and nuts. Note the “typically”, lots of exceptions.
'29 Pickup
Member
I'm thinking I might order a selection box or two of UNC and UNF bolts and nuts. My local hardware store has limited sizes in high tensile UNC/UNF (zinc) and it's a fair drive every time I need a bolt and that's if they have it.
Synchro909
Well-known member
Over here in the SE corner of the continent, imperial threads have disappeared from hardware stores but you can still het them from nut and bolt specialist outlets. I grew up with Whitworth threads and it it weren't for owning a Model A, I would have forgotten all about them. I recently sold a 1928 French car I restored over the past couple of years. Nuts and bolts were a breeze - all metric.
As has been said above, BSW and NC have the same thread count (up to 1/2") but different thread form. BSW is 55° thread form but NC is 60°. Why they changed things for 5° is a mystery to me.
'29 Pickup
Member
I find that the fastener suppliers are a bit sniffy about posting out small quantities....minimum order size or it's a flat out no...or they have big minimum charge for posting a few bolts. Plus it can take a week to get post from the nearest city.
So I'm looking at the mixed selection boxes....do you think that this sort of thing would be of much use, or am I likely to find only a few bolts which are what I need given the sizes? $70 each box. (seem to be grade 5 but I thought only grade 8 are high tensile?).
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'29 - my $0.02 USD worth.
Assortments are fine for washers and nuts, but I suspect that you will find that bolts are a different story. And Grade 5 is "normal" for automotive fasteners, but there are certainly areas where Grade 8 would be appropriate.
Here in the USA, I have run into three issues with typical industrial fasteners available in boxed assortments or even quantity boxes such as you show as applied to the Model A.
1. Most industrial fasteners are now plated (either zinc or cadmium), whereas on the Model A few were. Model A fasteners were typically either bare steel or finished in a black oxide or "raven" coating. You can acid-strip the zinc and do your own phosphating, but it's a pain. Some specialty suppliers like Grainger or McMaster-Carr do offer oxide-coated fasteners, or you can order them from the Model A suppliers.
2. Again, maybe this is a USA thing, but nowadays each bolt head (and increasingly, washers) has a three-letter identifying mark stamped into it. The mark is unique to each bolt size, thread pitch and length. This is so that minimum-wage cashiers can simply punch in the code rather than know anything about what they are selling. Model As never had these marks. Again, if it matters to you those can be filed or ground off, but in turn that destroys the plating.
There are also sometimes radial lines on bolt heads indicating grade (e.g., three radial lines for Grade 5, six for Grade 8), which again were not present in the Model A era.
3. I've found that a typical assortment like you show will give you a few examples of each bolt length. It's a crap shoot whether there will be enough to do what you want to do. For example, if you wanted to replace the bolts holding the axle housings to the banjo in your rear end, that takes 20 bolts, and it's unlikely that you'll find 20 bolts of the correct pitch and length in a boxed assortment.
This discussion does not even touch that some Model A bolts (e.g., timing cover bolts) have special thick or rounded heads, that some Model A bolts are drilled for castellated nuts, and that some have the heads drilled for safety wire.
Having said the above, having a good assortment of bolts, nuts and washers around would not hurt. There is always something falling loose on a Model A that you need to fix NOW, and there are also the accessories that you might want to install. But if you're interested in having a good supply so that you can replace what you need to replace as you go through and maintain your Model A, you might want to consider specific bolts sets available from the Model A vendors. It might be worth a call to Don Snyder (Snyder's) or Steve Becker (Bert's Model A Store) to see if they have any suggestions.
Yes, I know that shipping is a significant issue with USA parts to Australia, both cost and time. Perhaps some of you other Oz Model Aers can suggest something.
Another aside - the Model A is almost completely Unified National (UN) either coarse (UNC) or fine (UNF) standard thread pitch, 60 degree included angle. There are a few tapered pipe thread fittings (NPTM or NPTF), and I believe a couple of metric threads in the Zenith carburetor. A few of the thread sizes are not common any more (for example, there are a number of #12-24 screws like the floorboard screws, those are available but typically in a hardware store you would jump from #10 machine screw to 3/16").
Good luck.
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'29 - forgot to mention. You may find that with your engine stand you need to make some tubular spacers, and get much longer bolts, to allow you to get the arms of the mounts around the end of the installed crankshaft. I did. My recollection is that I had to add about three inches. An alternative would be to bolt your engine stand to the side of the engine at the water inlet using this engine stand adapter.
'29 Pickup
Member
Many thanks for that assessment JayJay....just what I was hoping for.
My plan is to get the car mechanically sound and as reliable as it can be.
I'm not looking to win at Pebble Beach, so it's not for any sort of competitions, except perhaps, best jalopy.
Not bothered by marks on bolt heads or the look of zinc but it seems the choice here is either zinc or black in UNC/UNF which I think is about the same as Raven....rusts in a few months unless you paint it. So perhaps we're not as badly supplied as it could be bearing in mind the ubiquitous metric system.
For special bolts such as drilled etc there is a Snyder's agent here who sell a lot (but not all) of Snyder's gear.
Thanks again.
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