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| Mk2 Cooper S engine rebuild https://www.ausmini.com/forums/viewtopic.php?f=5&t=99866 |
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| Author: | Screamin [ Sun Apr 12, 2020 7:44 pm ] |
| Post subject: | Mk2 Cooper S engine rebuild |
Hi Folks I have done a bit of searching to no avail hence this post. First the engine. The car is 1970 matching numbers Cooper S I am in the process of doing a full resto on. Body work (shell) just started. Engine underway also. The motor was bored to 1380 and has some clearance wear so it is being resleeved back to standard 1275. I have bought a Cooper S rebuild kit from Minisport. They advised the kit pistons give a reduced compression back to 9.3:1 which they advised is a good option given our lower octane fuels in Aus. Any thoughts on this? Secondly I have ordered a 266 Kent cam kit. The original rockers and shaft have got wear and a i am wondering if I should purchase new bushes and shaft for about $100 or go with the forged 1.5 ratio set they sell or the more expensive roller type. With the 266 cam are the 1.5 rockers worth looking at or should I rebush/new shaft the original set? I am not fussed on originality in this case as under cover! One of many questions to come I am sure. Hope you are all having a nice Easter weekend. Cheers Richard Perth |
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| Author: | Screamin [ Sun Apr 12, 2020 9:55 pm ] |
| Post subject: | Re: Mk2 Cooper S engine rebuild |
Well I pushed the button and bought a set of the C-AHT436 Cast high lift 1.5 rockers. Hopefully I have made the right move to work with the Kent 266. The rocker feet? looked a tad worn so cheapest option i think. Feel free to let me know if I should have gone another way. Richard |
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| Author: | simon k [ Sun Apr 12, 2020 10:25 pm ] |
| Post subject: | Re: Mk2 Cooper S engine rebuild |
Screamin wrote: They advised the kit pistons give a reduced compression back to 9.3:1 which they advised is a good option given our lower octane fuels in Aus. Any thoughts on this? I don't agree - most happily run > 10:1 on 98RON which minisport - UK or South Aus? |
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| Author: | Screamin [ Sun Apr 12, 2020 10:43 pm ] |
| Post subject: | Re: Mk2 Cooper S engine rebuild |
South Australia. |
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| Author: | Screamin [ Sun Apr 12, 2020 10:46 pm ] |
| Post subject: | Re: Mk2 Cooper S engine rebuild |
This was the kit I purchased. They were not sure if they had the standard bore 1275 pistons in stock then found some. They quoted the 9.3:1. Might these be lower compression pistons or all they all the same given the crank in the Cooper is a longer stroke. |
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| Author: | Screamin [ Sun Apr 12, 2020 10:47 pm ] |
| Post subject: | Re: Mk2 Cooper S engine rebuild |
https://minisport.com.au/engine-rebuild ... s-oil-pump Apologies link above |
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| Author: | Scoop [ Mon Apr 13, 2020 8:27 am ] |
| Post subject: | Re: Mk2 Cooper S engine rebuild |
The long stroke cooper was a 997, not the 1275 cooper S that you are building. The 1275 engines all had the same stroke. |
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| Author: | Screamin [ Sun Apr 19, 2020 4:49 pm ] |
| Post subject: | Re: Mk2 Cooper S engine rebuild |
Thanks for info (and correction!) on my cooper 1275 build. will be running standard 9.75 comp more than likely. My Kent 266 and 1.5 mini sport cast rocker set have arrived awaiting the resleeve and minor head work to be fitted. I have researched the hell out of the suitability of the 1.5 rockers to my 1275. I am just chasing confirmation by members who are familiar with this set up as to whether to keep the 1.5s or get a standard or 1.3 set. I have read some posts stating a loss of mid range but very slight increase in top end on a higher spec cam but more on a standard cam. So do I return them and swap out for another set or throw them in? Thanks Richard |
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| Author: | FNQ [ Sun Apr 19, 2020 5:21 pm ] |
| Post subject: | Re: Mk2 Cooper S engine rebuild |
I don't know the cam, but believe it is at the milder end of scale. ( There are other 266 timed cams that offer a bit more particularly in low to mid range), Having the 1.5 rockers will make it behave more like a 276 duration. I have run a 1310cc with 260 cam and paired it to a minispares 1.3 rocker. The last part of the equation is that it runs a only slightly tweaked head, ( basically cleaned up around a larger input valve). The drive is fun, the noise is endearing but the performance is not really spirited...... think more Mr Bean rather than Nick Swift. Next build on that motor will involve some proper head work. That motor runs CR 9.75 just fine. In terms of carbies, that motor ran twin HS4s with number 6 needle ( similar to more common CP4),,, but right now it is running a single HS 6,, and this set up is fractionally better than the twins. I think you will be able to pair those parts together quite well and be well pleased with it. ( but don't expect a fire breather) |
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| Author: | Chris.Williams [ Wed Apr 22, 2020 8:38 pm ] |
| Post subject: | Re: Mk2 Cooper S engine rebuild |
I’m just coming to the end of this Cooper S build. Taken a bit of time, but I think my customer will be happy with the results. Attachment: F4BD9E20-57C1-461C-96C3-C84DB9ECAE5A.jpeg
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