Ok i seem to have two different types of crankshafts, one has (did have) small brass plugs in the oil holes but have been rubbing and one fell out when the bearing came apart. What should i do with them if we end up using this crank?



This crank doesnt have them, looks better condition but haven't measured them yet.

Do the part numbers stamped in the cranks tell you anything?

_________________
Cheers
PeterN
3x Leylands
1x 850
Mildura,
Victoria.

It is a 1098 (1100) Crank. Long stroke small bore. Speak to an engineer that "Knows Mini Cranks" (ie G. R.) and that Plug might be able to be re fitted back in the hole or a new one made up and fitted. Do not use without it.

_________________
DID I MENTION THAT I AM THE BEST SUPPLIER FOR MINI ELECTRICAL PARTS AND REPAIRS?
"Let us remove your "SHORTS"

These are both 1275 cranks. The brass plug in the big end journal indicates this is a cross drilled crank and the plug is used to plug off that oil drilling. A new plug could be made but best bet all round is to have the hole(s) tapped and have grub screws fitted. A 6mm grub screw does the job. Take it to an engine shop to have done, don't try it at home.

All my race cranks are done that way and had to have it done to a 1100S crank (same as yours) recently as well.

_________________
Steve

Can you explain this a bit further? I had my crank cross-drilled on the mains and was told by someone to watch out for loss of oil pressure? Mines an A+ crank.

Many small journal 1275 cranks (including Cooper S) had the big ends drilled as normal then cross drilled, and the original outer hole plugged with these brass plugs.
The idea was not to get more oil up there, but to put the oil into the bearing at a lesser radius from the crank axis. This reduces oil throwoff due to centrifugal force.

With A+ engines the designers thoughtfully(!!??) put a plain bearing into all 3 main bearing caps, with no oil groove. This was ostensibly to give greater load bearing capacity for turbo engines. Unfortunately, as the mains only have 1 drilling to the big ends, the big ends all get starved for 1/2 a revolution (from 9 o'clock to 3 o'clock, where the load is greatest..
There are 2 ways to fix this:
1. Use A series bearings (cheaper, too). You just need to provide an offset tang slot for the bearing shells. or,
2. Cross drill the mains so there are 2 oil pickup points to the bigends.

_________________
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.

I don`t like cross-drilling cranks,,, it weakens them considerably (IMO)

_________________
No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

When I do A+ motors I fit A series bearings. The last 1293 A+ I did up, all 4 crankpins were worn oval and the big end shells stuffed.

_________________
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.

The crossed drilled crank is the one in best condition, the mains on the other have grooves worn in them. The brass plugs have a small hole drilled so they dont actually completly blank off. As you can see they have been rubbing and one was missing altogether. So which is the best to use, get new plugs fitted (assuming the journals all pass) or get the second crank's, journals ground done a size?

_________________
Cheers
PeterN
3x Leylands
1x 850
Mildura,
Victoria.

I'd put grubscrews in the crossdrilled one.

_________________
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.

The plugs still had small holes in them, drill holes in the grub screws as well?

_________________
Cheers
PeterN
3x Leylands
1x 850
Mildura,
Victoria.

If you want, doesn't matter really.

_________________
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.

Yep I get you. So what do the G.R. mini cranks have? Are both big ends and mains cross-drilled or just the mains?

I'm not sure what drillings are in his smick 8 counterweighted race cranks from Melbourne..
But I know he prefers using A series bearings too in an A+ block. They eliminate the lube starvation problem without any crank drilling.

_________________
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.