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| 1275 A series in Mini and Sprite/Midget differences https://www.ausmini.com/forums/viewtopic.php?f=2&t=86644 |
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| Author: | Fat Boy Dave [ Fri Jul 25, 2014 1:42 pm ] |
| Post subject: | 1275 A series in Mini and Sprite/Midget differences |
Other than the gearbox and sump, what are the differences in the 1275 that they put in the Mini and the one that they put in the sprite/Midget? Can I put a 1275 engine from a Mini into a Sprite? |
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| Author: | Mick [ Fri Jul 25, 2014 3:12 pm ] |
| Post subject: | Re: 1275 A series in Mini and Sprite/Midget differences |
Certainly the crank..it is flanged instead of having a tail. So you will need the crank (and rods if different big end journal sizes). Kev will be up later on, he describes the conversion thus from sprite to midget, but I'm unsure what specifically he is describing to the rear main caps: drmini in aust wrote: It's an easy job to fit it to a Mini. The bolt holes of the Sprite/Midget sump line up with a Mini or A/A box. I did this with a 1098 AH Sprite motor years ago.
Work needed: 1. Machine the return thread housing bottom half from the rear main cap. 2. Undo the return thread top half from the rear of block block and discard. 3. Unscrew and remove the oil Midget pickup pipe. On a 1098 Sprite the Mini O-ring seals OK to the block there, but check size. If the O-ring is too small to seal, screw a threaded bush in there and make flush. 4. Obtain a 1275 primary gear to fit your crank. 5. Cut the 2 engine mount wings off the front engine plate (not needed in a Mini). [edit] Of course you need big journal rods to suit that crank, otherwise grind the crankpins down to 1.625" (stroke it too if you want) and use slightly narrowed 1275 Midget or Cooper S rods. |
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| Author: | drmini in aust [ Fri Jul 25, 2014 3:17 pm ] |
| Post subject: | Re: 1275 A series in Mini and Sprite/Midget differences |
It's easier to put the Sprite engine into a Mini than vice versa, I've done that (with a 1098 Sprite motor) back in 1967. 1. The crank tail is different, Midget one is shorter and has a flange. You need a Midget crank. 2. The oil pickup hole in the block is threaded on a Midget, not so on a Mini. Should be able to tap it out. 3. The rear main cap on a Midget is wider and has an oil return function. This bit gets machined off when you stick it in a Mini. You would need to duplicate this somehow with a bolt on piece to use a 1275 Mini rear cap.. might be easier to buy or make a new Midget rear cap and line bore it with the block. 4. The top 1/2 of the Midget rear main's oil return channel would need to be bolted onto the 1275 Mini block. Will need to drill & tap some holes. Have fun... [edit] 5. The Midgets all had small journal crank & rods so you can't use late 1275 big journal rods. |
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| Author: | simon k [ Sat Jul 26, 2014 10:36 am ] |
| Post subject: | Re: 1275 A series in Mini and Sprite/Midget differences |
My dad has a mini 1275 in a morris minor, complete with the original mini crank. Been in there for 25 years and used almost daily along with trips through central Australia Crank tail machined off, keyed and a boss (RX7 automatic I believe) fitted, along with other mods I don't know about. His mate did it for him. |
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