Um, i was putting a 998 engine together last night, and i snapped a rod bolt
Through overtightening due to torque wrench issues, anyway, its got me thinking, if i can snap one, whats the enging going to do to the rest?
these were not stock bolts, stamped with 10 lines and "FX".
so do i try find another, or revert to stock rod bolts.?
998
lightened rods
wade cam.
going for nice revvy smallbore.

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speed costs....how fast do you want to go...

Best rod bolts for a quick smallbore are `Unbrako' brand socket head capscrews, that's what GR uses. Lube em with oil or a smear of molygrease, do up to 40lb/ft, with no lockwasher.
Alternative is go buy ARP race ones from Minispares etc.
I don't trust the standard rodbolts, particularly if S/H. They make an awful mess of the motor and box if they let go. I bought a ventilated one last year.

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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.

Yea, i have a ventilated 998 block at home also, thats why im woried! worst thing is it was smeered with loktight so i had to get the broken half out fairly quickly!
its been a while since bolt grade school, what does 10 dashes mean?
what are a set of "unbrako" 's worth?

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speed costs....how fast do you want to go...

And I guess, just as importantly, where do you get them?

See http://www.americanfastener.com/technic ... _steel.asp
can't see any bolts there with 10 marking.
Unbrakos are grade 12 I think. But don't buy Chinese made...

see http://www.unbrako.com/
download the catalog

<edit> I'd avoid ANY fasteners that are plated.. I once peeled the threads off some plated Grade 8 (7/16 UNF) diff bolts before they got up to the torque setting.....

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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 two rod bolt sizes from factory

The smallbores all run a 3/8" UNF hex bolt. Don't have one handy right now but I think were all the same.

The 1275s with S rods (ie small journal crank) use a 3/8" UNF `shaped head' bolt, and nut.

The 1275s with big journal crank (both A series and A+) use 11/32" UNF `shaped head' bolts and nuts.

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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.

Interesting. S has bigger diametre rod bolts than big journal ones. mmmmmmm yummm

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1964 Morris 850, 1330 Supercharged - 81.8hp atws.
1975 Leyland Mini S 1100S powered - Nice and reliable.
1977 Leyland Mini LS - Project LS-T

That also means they have less meat in the conrod...
6 of one 1/2 dozen of another

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Miniworx Centre 0883741299
Sooperdooperminicooperexpertengineering
Online BMW Mini Shop

Bugger!!

Less meat = lighter. Less meat also = more chance of break!

To quote the Blues Brothers, or close enough

Ah that's ok. My motors not a race motor.

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1964 Morris 850, 1330 Supercharged - 81.8hp atws.
1975 Leyland Mini S 1100S powered - Nice and reliable.
1977 Leyland Mini LS - Project LS-T

All Cooper S rods are made of EN24V, the good stuff.
Big journal rods for the 1275 A series were 50g heavier than S rods and made from EN19 and later EN16.
A+ rods are nice and light, made of EN15. In spite of this Vizard says they are fine for a 7500 rev limit.

Weakest point on all these 1275 rods is the bolts- if S/H you don't know how old they are or how used. Buy new ones, preferably ARPs.

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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.