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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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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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

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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Same diameter but different length. Could probably shorten them? I will compare 2 this morning.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

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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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Is there anyway to check to see if the old bolts are OK to go again?

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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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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

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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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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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

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.

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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1972 Mk3 Mini 1000, 1150cc supercharged.
https://www.ausmini.com/forums/viewtopic.php?f=3&t=95872

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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Pop over to MED's website - their AFS main studs and nuts are excellent, and they do kits for the small-bores.