concours
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"Chuck" them in the bin
Head bolts cracks -stretch marks
- Thread starter Ian James
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lcrken
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Thanks. You are probably right. Like Eddie, from the text of Ian's post, I assumed the pictures were of the old bolts that were going back in. My mistake. On closer inspection, it does look like those are the ss bolts. And the overall machining and surface finish quality is pretty bad.
Ken
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Can you expand on the FullAuto bit please?
concours
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What was wrong with the original carbon steel through bolts?There is high strength stainless steel and there is regularr SS. Here's what can happen with regular SS cylnder through bolts in a large displacement high compression race engine.
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There is nothing wrong with the original grade 8 allen carbon steel 850 cylinder through bolts. They are strong enough. But Carbon steel will rust when exposed and that is why Maney uses SS bolts - because the through bolts are exposed with Maney cylinders (500 - 1007cc). The broken bolts I showed were in Maney cylinders.
BERT
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I think they are chuck marks from the manufacturing process. After turning the blank, it would be logical to chuck the blank where those lines are to make the threads.
Bolts won't look that way (those scratch marks) from stress failure especially more than one showing the same pattern.
I wouldn't hesitate to reuse any original bolt any where on these machines after proper inspection and fine filing and thread chasing because replacements may be inferior quality.
Bolts won't look that way (those scratch marks) from stress failure especially more than one showing the same pattern.
I wouldn't hesitate to reuse any original bolt any where on these machines after proper inspection and fine filing and thread chasing because replacements may be inferior quality.
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concours
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There is nothing wrong with the original grade 8 allen carbon steel 850 cylinder through bolts. They are strong enough. But Carbon steel will rust when exposed and that is why Maney uses SS bolts - because the through bolts are exposed with Maney cylinders (500 - 1007cc). The broken bolts I showed were in Maney cylinders.
I understand the jewelry trend, I guess. Form before function. I understand it, but can't agree with it.
In the olden days, we'd just shoot some black spray paint on them before assembly, call it good.
I understand the jewelry trend, I guess. Form before function. I understand it, but can't agree with it.
Fast Eddie
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Steve Maney products do not fall into the form over function category!
These bolts were probably over torqued, and / or replaced with inferior.
But all that said, due to the expansion of the alloy barrel, waisted stem bolts are an improvement in this setting IMO.
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All Norton head bolts, head studs and cylinder through bolts should have reduced shanks so they can stretch to compensate for heat expansion instead of loosening or pullling out threads. You see reduced shank head bolts being offered by several suppliers for various engines. See the difference in the two bolts below.
The broken bolts were Maney bolts on an Alky burning 920 engine with extra high compression and about 100 races on it and that was just a little too much strain. ARP bolts are stronger than either regular stainless or the stock grade 8 allen bolts. So the 920 race engine now has reduced shank ARP SS cylinder through bolts. It was a very expensive failure because once the through bolts gave up the load was transfered to the short front case stud and the front of the case broke off.
The broken bolts were Maney bolts on an Alky burning 920 engine with extra high compression and about 100 races on it and that was just a little too much strain. ARP bolts are stronger than either regular stainless or the stock grade 8 allen bolts. So the 920 race engine now has reduced shank ARP SS cylinder through bolts. It was a very expensive failure because once the through bolts gave up the load was transfered to the short front case stud and the front of the case broke off.
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I wonder if the waisted bolt is roll formed to produce the smaller diameter.
I am not talking about roll forming the theads, but roll forming the reduced diameter.
In Jim Comstocks video, where he appears to be prototyping the waisted bolts, he is milling them, not roll forming them.
Matt from CNW commented earlier in this thread, but it sounds like the ARP bolts have roll formed threads, not roll formed reduction in diameter. In which case, I don't see why you can't just modify the stock bolts, kind of like in Jim's video.
Or is it that the original bolt alloy will not function with a reduced diameter?
I am not talking about roll forming the theads, but roll forming the reduced diameter.
In Jim Comstocks video, where he appears to be prototyping the waisted bolts, he is milling them, not roll forming them.
Matt from CNW commented earlier in this thread, but it sounds like the ARP bolts have roll formed threads, not roll formed reduction in diameter. In which case, I don't see why you can't just modify the stock bolts, kind of like in Jim's video.
Or is it that the original bolt alloy will not function with a reduced diameter?
cNw
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Stephen,
The head bolts that ARP makes for me have rolled threads and the waisted portion is also formed, not milled. This ensures consistent strength throughout the bolt.
When Jim was prototyping the head bolts, they were milled/machined.
As far as modifying a stock bolt, not sure about that. If it’s a used one, I would say definitely not. It’s been under load for 50 years. To then machine it and make it smaller diameter and then torque it again, you would be asking for a failure to happen.
If it is a new stock bolt, you would still be taking a risk. You would essentially be reducing a 3/8 bolt to a 5/16. Then torque that to 3/8 spec. Without knowing exactly the actual material the bolt was made from and how it would do in regards to being machined and torqued to a certain load after it’s been made smaller, that’s a lot to be guessing about and with possible bad consequences
Matt
The head bolts that ARP makes for me have rolled threads and the waisted portion is also formed, not milled. This ensures consistent strength throughout the bolt.
When Jim was prototyping the head bolts, they were milled/machined.
As far as modifying a stock bolt, not sure about that. If it’s a used one, I would say definitely not. It’s been under load for 50 years. To then machine it and make it smaller diameter and then torque it again, you would be asking for a failure to happen.
If it is a new stock bolt, you would still be taking a risk. You would essentially be reducing a 3/8 bolt to a 5/16. Then torque that to 3/8 spec. Without knowing exactly the actual material the bolt was made from and how it would do in regards to being machined and torqued to a certain load after it’s been made smaller, that’s a lot to be guessing about and with possible bad consequences
Matt
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Of course you can modify your stock bolts. But if you reduce the diameter its a lot of machining and the stock material is not the best available. The only two drawbacks are:
1, machining marks (you can polish out).
2. reducing the diameter makes them "twist" more when tightening (springy feel - especially with long bolts).
Ken the pics I posted later are of the ss bolts not the originals ,no need to feel stupid I should have posted them with the first post apologies Ian
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