can somebody please explain to me how to determine a large journal crank from a standard cooper s/GT journal crank??

Also are all 1100S cranks large journal??

Also can any large journal crank be stroked or they have to be a non-touched crank

AS i want to start colecting bits and peiced to build a go hard stroker motor

Thanks for you help

Brenton

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Large journal cranks are just that, the big end journals are much bigger than a std 1100 S or Cooper S crank. 1.625 for the little one & 1.750 for the big one.
The main bearing journals remain the same size between the two.

1100S cranks were both small and large journal

Only large journal std size cranks can be stroked, there offset to the desired stroke & macnined down to the smaller journal size, requiring S rods.

Also, if you want to use a 1100S small or large journal crank in a S block you will need oversize thrusts that are no longer made. I have a few sets if you need them.

Regards
David

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850man,

are you sure that only a standard crank can be offset ground to increase the stroke? I don't see why a reground crank cannot also be stroked using the same process. Of course, the amount that the stroke is reduced will be less, but not much so.

It really is best" to use a std/std large journal for increasing the stroke,,, (if you can find them) .... it is, after all, the whole point of doing it... altho you can go further past std small journal size when doing it to gain some back if you use an already undersized large journal, but it starts to get weaker the smaller you go & you also end up with less to carve off (if need be) at any later stage for repairs.

I`ve made .080 undersized cranks for 2 of my road engines , takes them to about 86mm stroke (makes them 1510cc-ish) with 74.7mm bores


I have a big one

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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.

They ARE still made in Oz, by ACL.
p/no is 2T2204+.030. I'm looking at the packet...
I got them from www.minis.com.au

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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.

I was at a mates and he is getting rid of some of his stuff and he has two cranks there (that i saw amongst others) that are 12G1505A in raised lettering. By veiwing with the naked eye one has larger journals than the other.

* Is the one with the larger journals a large journal 1100S crank??
(or i really have to measure it ?)


* How likely is it that it would be cracked (ie was it a common fault?)


* Also i have been told that 1100S blocks are better for performance than S blocks because they are stronger without the removable chest covers.
(plus my mate doesnt want me to use an s block because it is an S block)

* Do i have to use S conrods to stroke it?

* So what would an appropriate price be to pay for the 1100S block and journal with and without rods??

Thanks everyone for your help because this is a learning curve for me, and something i have little knowledge about, but am keen to learn


Thanks Brenton

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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 Kevin, Very much appreciated.

Just what i wanted to know

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Bubba,,,, If/when you decide to go the stroker cranky route,,, you will need those "S" con rods yes,,, but you also need to skim about 15thou of each side of them...K?

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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.

ok why do i need to do that???
are the journals smaller in width?


Do you have the tools do that?

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Mini man,
so the answer to my question is that you CAN offset grind a non-standard crank. Maybe it's not the best, but given how hard it is to find a standard crank, most people would find it much easier to use a 10-under crank. Since you are grinding from a 1.75 inch diameter to a 1.625, the amount of .010 is insignificant in terms of weakening the crank or reducing the amount of stroke change. Once you have your 1.625 journal, you can grind it undersize as needed to rebuild the engine after crank wear. I really don't see any problems with offset grinding an undersized crank unless you consider losing .005 in stroke length to be a problem.

mini7boy,,, you`re perfectly correct, yes.

the strength part i was getting at was more to do with grinding it down further than std small journal size like i have with my .080 undersize cranks,,,, very "iffy" indeed,,,

edit--> but you could grind it down to .010 or .020 to gain back the extra stroke without tooo much compromise of integrity.

& Bubba,,, just about any machine shop or engine reco shop can mod the rods for you, easy-peasy... & yes it`s cause they`re narrower in the journals than the small journal cranks.

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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.

Unless you are making a stroker, I reckon the small journal 1100S ones are a better crank. Most were tufftrided (surface hardened), unlike the 12G1505 ones which were all soft over here.

BTW I've been told nobody is doing tufftriding any more in Oz (even in Melbourne), you would need to send the crank to UnZud to get it (or similar process) done.

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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.

cryogenic treatment is the go these days i hear,,, havn`t tried it yet, i`m still old skool & nitride them

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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.

ACL thrusts are NOT made anymore. The last production of +30 thrusts ACL made were a special order through a mate i have that works there and was a once off. I had them produced as i was sick of hunting around trying to find old stock and when they did turn up they cost a fortune. The sets that Linsey sells he got from me.

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Have a Nice Day.
If already having a nice day please disregard.