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| Small Bore Main & Big End Bolts https://ausmini.com/forums/viewtopic.php?f=2&t=95410 |
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| Author: | timmy201 [ Wed May 17, 2017 5:42 pm ] |
| Post subject: | Small Bore Main & Big End Bolts |
Hi All, I'm after some suggestions for my 1098 engine. At the moment I've got a set of standard main and big end bolts, although the I got the engine as a non-runner with unknown history. So the choices are: Old standard ones (castellated head for the main bearings e.g. http://russellengineering.com.au/project-68mm-part-1/ ) New standard ones Upgraded - ARP etc bolt or studs? Locktabs or Loctite or neither? Cheers, Tim |
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| Author: | drmini in aust [ Wed May 17, 2017 10:44 pm ] |
| Post subject: | Re: Small Bore Main & Big End Bolts |
ARP rod bolts (or Unbrako SH cap screws), std castellated mains or ARP mains. Oil the threads, no Loctite or tabs. |
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| Author: | timmy201 [ Thu May 18, 2017 7:55 am ] |
| Post subject: | Re: Small Bore Main & Big End Bolts |
Thanks Kev. The ARP ones aren't too expensive... http://www.ianboettcherraceparts.com.au ... -6207.html http://arp-bolts.com/kits/ARPkit-detail ... cordID=794 Do the main studs for the 1275 fit the 1098 too? |
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| Author: | drmini in aust [ Thu May 18, 2017 8:05 am ] |
| Post subject: | Re: Small Bore Main & Big End Bolts |
Same diameter but different length. Could probably shorten them? I will compare 2 this morning. |
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| Author: | drmini in aust [ Thu May 18, 2017 8:46 am ] |
| Post subject: | Re: Small Bore Main & Big End Bolts |
1275 main bolts are 5-6mm longer than 998 bolts. But they have the same plain shank length above the thread. So cut 5-6mm off, deburr the end and they will fit fine. Note the castellated bolts are fine without washers or tabs, but the hex head ones or ARP main bolts need ARP or similar hardened washers. [edit] This because the castellated head ones have more contact area under the head. As I said above, oil the threads and under the heads. But if ARP, use their moly lube and torque settings. |
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| Author: | timmy201 [ Thu May 18, 2017 1:45 pm ] |
| Post subject: | Re: Small Bore Main & Big End Bolts |
Is there anyway to check to see if the old bolts are OK to go again? |
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| Author: | drmini in aust [ Thu May 18, 2017 2:34 pm ] |
| Post subject: | Re: Small Bore Main & Big End Bolts |
Look carefully at the threads with a magnifying glass, if not stretched they should be OK on a road motor. Main bolts are Grade 8. I have broken only 1 main bolt in my life, and that was back in 1967...! But if you intend to buzz it to 7500+ I would fit new ARP rod bolts. |
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| Author: | timmy201 [ Thu May 18, 2017 5:30 pm ] |
| Post subject: | Re: Small Bore Main & Big End Bolts |
Looks like a small bore ARP stud kit is out there, and also bolts. http://www.7ent.com/products/arp-main-c ... n0119.html http://www.7ent.com/products/main-cap-b ... 148-1.html |
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| Author: | drmini in aust [ Thu May 18, 2017 7:40 pm ] |
| Post subject: | Re: Small Bore Main & Big End Bolts |
Ask GR about using the studs. Personally, I would stick with bolts. Except on a Cooper S where the studs locate the bearing caps. |
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| Author: | ba_dm_tsh [ Fri May 19, 2017 8:46 am ] |
| Post subject: | Re: Small Bore Main & Big End Bolts |
If you plan to fit anything but standard bolts it is essential you check your main tunnel and rod bores for size. ARP bolts/studs and the like have different clamping loads which can change the shape of all your bearing bores. |
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| Author: | hpal [ Fri Jan 31, 2020 7:16 am ] |
| Post subject: | Re: Small Bore Main & Big End Bolts |
timmy201 wrote: Hi All, I'm after some suggestions for my 1098 engine. At the moment I've got a set of standard main and big end bolts, although the I got the engine as a non-runner with unknown history. So the choices are: Old standard ones (castellated head for the main bearings e.g. http://russellengineering.com.au/project-68mm-part-1/ ) New standard ones Upgraded - ARP etc bolt or studs? Locktabs or Loctite or neither? Cheers, Tim Hi Timmy, I'm Building a 1098 at the moment and have been pondering which way to go regarding engine bolts, and wanted some advice on how you did yours. I've got the castellated main bolts which I'll reuse (lock tabs? washers? loctite or oil?), but have one big end head rounded off and will either replace it with a good used one or use the unbrako SHCS's. I'm not keen on buying the ARP bolts due to the price, I'd use the cap screws if anything. So, which way did you go with the big ends? Original bolts? Loctite or oil? lock tabs? I kinda like the loctite idea if not using lock tabs.... Cheers |
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| Author: | timmy201 [ Fri Jan 31, 2020 7:28 am ] |
| Post subject: | Re: Small Bore Main & Big End Bolts |
Mains were castellated stock bolts, and I bought 200-6207 ARP for the big end bolts. The ARP bolts were cheaper than stock replacements actually - about $125 for the set delivered. No locktabs, I used the ARP lubricant (you can also buy it separately). |
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| Author: | Fallingbrick [ Fri Jan 31, 2020 8:56 am ] |
| Post subject: | Re: Small Bore Main & Big End Bolts |
Pop over to MED's website - their AFS main studs and nuts are excellent, and they do kits for the small-bores. timmy201 wrote: Hi All,
I'm after some suggestions for my 1098 engine. At the moment I've got a set of standard main and big end bolts, although the I got the engine as a non-runner with unknown history. So the choices are: Old standard ones (castellated head for the main bearings e.g. http://russellengineering.com.au/project-68mm-part-1/ ) New standard ones Upgraded - ARP etc bolt or studs? Locktabs or Loctite or neither? Cheers, Tim |
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