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| Cooper s crank in an 1100s Block... is it possible? https://www.ausmini.com/forums/viewtopic.php?f=2&t=98167 |
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| Author: | nickprocter [ Tue Jan 15, 2019 11:52 pm ] |
| Post subject: | Cooper s crank in an 1100s Block... is it possible? |
Hey all, I have a late 1100s 1275 block and caps that I finally managed to acquire... problem is it did not come with a crank and I’m struggling to find one that doesn’t cost the earth Have an opportunity to buy a relatively cheap Cooper S crank but wondered if they would be comparable. I understand they are small journal? Unfortunately I have no idea wht this means.. I’m a serious novice when I comes to engine builds so please be patient with me! Is it possible to use the cooper s crank in the 1100s block? If so what would this entail? Cheers Nick |
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| Author: | Ian_B [ Wed Jan 16, 2019 7:20 am ] |
| Post subject: | Re: Cooper s crank in an 1100s Block... is it possible? |
Pretty sure you need different thrust washers.Im sure the Doc will confirm |
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| Author: | simon k [ Wed Jan 16, 2019 2:13 pm ] |
| Post subject: | Re: Cooper s crank in an 1100s Block... is it possible? |
yeah, Dr Mini will say that it needs the thrust bearings surface ground thinner as the S crank is thicker in the centre journal, otherwise no problem small journal means that the 'big end' journals where the conrods mount are the smaller of the two sizes that were available. This is a good thing as the conrods are lighter. I believe they went to the larger size when they went to an inferior steel for the cranks |
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| Author: | Ian_B [ Wed Jan 16, 2019 3:14 pm ] |
| Post subject: | Re: Cooper s crank in an 1100s Block... is it possible? |
Simon I know that there is a case where lots thicker needed and they are available. |
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| Author: | drmini in aust [ Wed Jan 16, 2019 6:27 pm ] |
| Post subject: | Re: Cooper s crank in an 1100s Block... is it possible? |
You need to take about .016" off standard thrusts to fit an S crank into an 1100S etc block. [edit] I run one. To fit an 1100S crank into an S block you need thicker ones as Ian said. Use +.030" ones and surface grind to fit. Approx .016" needs to come off. These thrusts are each .030" thicker, not total .030" for the pair. Don't use the shop manual's .003" end float if going to rev it, the crank webs will flex and grab the thrust washers at high rpm. A recipe for overheating the centre main. As I found out once at Wakefield Park on a 1000 mile fresh rebuild. I use .007" now. |
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| Author: | Ian_B [ Wed Jan 16, 2019 7:17 pm ] |
| Post subject: | Re: Cooper s crank in an 1100s Block... is it possible? |
My local man that could do the machining has sadly closed down due to the bitch that is cancer |
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| Author: | drmini in aust [ Wed Jan 16, 2019 8:27 pm ] |
| Post subject: | Re: Cooper s crank in an 1100s Block... is it possible? |
Ian, PM sent. |
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