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Mini Engine Re-build - Small Bore Advice Wanted
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Author:  justincase42 [ Wed Jun 30, 2010 3:37 pm ]
Post subject:  Mini Engine Re-build - Small Bore Advice Wanted
Howdy,
Just starting an engine rebuild and not sure what direction to head with it. I have a tonne of small bore stuff so I am going to stick with that, I am after a Fast Road Donk that can sit on the highway.

Engine canidate number one.
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This engine has been build from Ausmini user parts by previous owner.
It has an Aaron cylinder head, doogie gearbox and lillie's old short motor. As per second pick, the gurgon pin c-clip has gone walkies and left a nice score in the bore. It is a 1100 block and crank and at 60 thou at the moment. Hopefully a re-bore will clean it up with GR 100 thou pistons

Engine Canidate Number two.
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It's a 1100 block that has been pocketed and at 60 thou. Bore appears to be in exellent condition. It has had a 12G940 head fitted in the past. I don't have a 12G940 Head so will have to source one if I go with this option. Cam bearings appear to be brand new, looks like it allso has new oil gallery plugs. Good chance this motor has had a re-bore and left to sit on the garage floor for a little while

So do I go with Engine one, hopefully 100 thou pistons, Re13 cam grind and maybe a 12G202 cylinder head with some work done on it.

Or do I go with engine number 2, maybe 60 thou pistons, Re13 cam grind, 12G940 Cylinder head.

Not sure what carby to run with or dizzy, any advise would be great.
Author:  mini-dunger [ Wed Jun 30, 2010 4:12 pm ]
Post subject: 
I have an 60. over 1100, cam, pipes, etc etc

I have a 1 3/4 su with all the Vizard stuff (pointless) done to it on a Minispares manifold.

It screams and pulls nice basically right from the bottom all the way to 6.5grand.

It idles with around 500rpm slop either way but its consistently inconsistent. .

I will rebush the su one day//
Author:  VulcanBB18 [ Wed Jun 30, 2010 4:55 pm ]
Post subject: 
Measure everything. While bores, crank, etc might look fine to the eye, when you measure them you really find what condition they're in.

As for the engine build itself, I start with what I want it to be (eg, road or race or something else?) then choose a cam & head combination, and then on from there.

Once you have use, cam & head worked out, the rest is just is what is needed to make that combo work out.

cheers

Jacob
Author:  1310/71 [ Wed Jun 30, 2010 7:35 pm ]
Post subject: 
Given you would want to re-bore and put new pistons in, I would take both blocks down to graham russell's and see which one he feels would clean up best.

I'd like to see engine 1 back on the road as a small bore screamer personally :D

That may well be the most economical rebuild if you don't have a head to suit engine 2.

Do you have the articles from Mini Experience on small bore engines?

KB
Author:  drmini in aust [ Wed Jun 30, 2010 7:36 pm ]
Post subject: 
S/H bores are never as good as they look. If it's pre-loved, I would rebore and fit oversize pistons as a matter of course. And of doing that you may as well give it some cubes- I'd bore it +.080" or +.100".
As for the head, I had a 940 on my 1220 motor way back when, it went bloody hard. But you will get better torque with a ported smallbore head.
As for rockers- I'd not go bigger than 1.3:1.
Author:  justincase42 [ Wed Jun 30, 2010 7:50 pm ]
Post subject: 
Quote:
Do you have the articles from Mini Experience on small bore engines


Sure do and the power tune 998 Donk book.

Looks like a trip to GR tomorrow ;-)
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