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| 1100 Crank into 850 Block https://www.ausmini.com/forums/viewtopic.php?f=2&t=95382 |
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| Author: | AJ [ Fri May 12, 2017 6:15 pm ] |
| Post subject: | 1100 Crank into 850 Block |
I know this has been discussed before , but I couldn't find it . What mods do I need to do to the 850 block to fit an 1100 crank into it and how far can the 850 block be safely bored to  . I want to keep the original 850 block looking stock but want more power
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| Author: | drmini in aust [ Fri May 12, 2017 8:34 pm ] |
| Post subject: | Re: 1100 Crank into 850 Block |
I fitted a 1098 crank to 3 motors back in the 60s. It involved machining each side of the centre main block web and cap by .062". Whilst keeping the thrust washer recess depths. Also removing .085" from the end webs for crank clearance. This was when 998 or 1098 blocks cost money and I had the machining setup to do it. You could narrow the crank webs instead but this will weaken it. These days, I'd save yourself all the grief, fit another block. 998 or 1098. |
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| Author: | IndigoBlueCooperS [ Fri May 12, 2017 8:49 pm ] |
| Post subject: | Re: 1100 Crank into 850 Block |
Google AC Dodd, as he was doing one of these recently. Looks like he is aiming for 1150cc, with an increase in stroke and bore. |
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| Author: | simon k [ Sat May 13, 2017 3:31 pm ] |
| Post subject: | Re: 1100 Crank into 850 Block |
AJ wrote: I want to keep the original 850 block looking stock but want more power is there any obvious external difference between the blocks? other than the engine number stamping.... |
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| Author: | drmini in aust [ Sat May 13, 2017 4:00 pm ] |
| Post subject: | Re: 1100 Crank into 850 Block |
simon k wrote: AJ wrote: I want to keep the original 850 block looking stock but want more power is there any obvious external difference between the blocks? other than the engine number stamping.... 850 block has 850 cast into the back where the 1275 etc badge goes on other blocks. From the front, no way to tell. |
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| Author: | GR [ Sat May 13, 2017 4:11 pm ] |
| Post subject: | Re: 1100 Crank into 850 Block |
Hi AJ I'v done a few of these mods now apart from machining the centre main down and the two end bearing caps as well as the block the four corners of the block have to be machined away to clear the counter weights. The one I just finished was 1100 pistons +40 202 head my valves 266ss cam and 2 1 1/4su's on the dyno it went well made just over 80 hp, but the thing that was interesting was he wanted to run the 997 cooper air cleaners (after market) they really killed the HP could not pass enough air through them. Hi SIMON They also have 850 cast on the side of the block. Graham russell |
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| Author: | AWOODY [ Sat May 13, 2017 5:27 pm ] |
| Post subject: | Re: 1100 Crank into 850 Block |
And with M needles can achieve great MPG , what needles did you use GR ? |
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| Author: | AJ [ Sat May 13, 2017 7:15 pm ] |
| Post subject: | Re: 1100 Crank into 850 Block |
Thanks for the replies guys . Hi GR what is the cost to machine the 850 block ? |
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| Author: | John Smidt [ Sun May 14, 2017 1:59 pm ] |
| Post subject: | Re: 1100 Crank into 850 Block |
drmini in aust wrote: simon k wrote: AJ wrote: I want to keep the original 850 block looking stock but want more power is there any obvious external difference between the blocks? other than the engine number stamping.... 850 block has 850 cast into the back where the 1275 etc badge goes on other blocks. From the front, no way to tell. It is important to note , a lot of 998 1098 blocks are much thicker on the bottom of the block, where it bolts to the gearbox. |
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| Author: | GR [ Sun May 14, 2017 6:36 pm ] |
| Post subject: | Re: 1100 Crank into 850 Block |
HI AJ To machine the block $350, what I failed to say was the sides of the block where the conrods go round has to be ground away as they hit. Graham Russell |
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| Author: | drmini in aust [ Sun May 14, 2017 10:28 pm ] |
| Post subject: | Re: 1100 Crank into 850 Block |
GR wrote: HI AJ To machine the block $350, what I failed to say was the sides of the block where the conrods go round has to be ground away as they hit. Graham Russell And once done, the conrods will probably hit the gearbox casing on an 850 box. More grinding to clear. |
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| Author: | Phil 850 [ Mon May 15, 2017 8:19 pm ] |
| Post subject: | Re: 1100 Crank into 850 Block |
drmini in aust wrote: GR wrote: HI AJ To machine the block $350, what I failed to say was the sides of the block where the conrods go round has to be ground away as they hit. Graham Russell And once done, the conrods will probably hit the gearbox casing on an 850 box. More grinding to clear. Depending on how original you want it to look, you could bolt a later 4 synchro box on with the 850 diff and gear lever. I have a 1100S in my 850 with this combination so it looks original inside the car. |
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| Author: | AJ [ Tue May 16, 2017 7:52 am ] |
| Post subject: | Re: 1100 Crank into 850 Block |
Thanks for all the info , looks like a bit of a challenge 
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