In the "good old days" the outer diameter size of the new sleaves were 73mm (or .095thou over) & therefore any bore bigger than that would not be able top be sleaved "UNLESS" special sleaves were made to suit in a larger diam.
all this is possible these days tho & there`s some pretty wacky (good) gear around now days, we had some special (Honda) sleaves made up to suit one engine we did & they had special flanges on top & special this & that & were of some "special" material etc etc etc ,,,lots of specials there hey?
But,,,very very costly ...& in my books just aint worth doin (YET)!!!!!!!!!!!!!!!! when good cond 2nd hand 1275 blocks become harder & harder to find, then that`ll be the time for "Mr Bulk Sleaving" to make some up.
anyways,,,the thing to do would be as the good Doc says & keep it as small as you can (within reason) & the best that we`ve found over the years is the 1412cc combination,,,still small enough in the bore to keep bore flex at a minimum, yet way big enough for decent grunt to be produced with the aid of a stroker crank,,,may dad designed some pistons to suit this exact combination & they have prooven to be bullet proof over the last 20 odd + years.
The stroker cranks commonly used are then (again as the good Doc suggests) a large journal ground down offset to small journal size & then narrow some "S" rods to suit & Bob`s your Aunty
we`ve been building those exact engines since 1969 for both road & race, easy-peasy
we`ve built many many an engine at bigger than 73.5mm bore in "offset" guise & some break through some don`t,,,not worth the muck around if you only have one block to play with,,,& yeah, i wouldn`t recomend the A+ blocks at all, YUK!!! but hey,,,you takes your chances some times,,,heck my own roady donks (2 off) went out to 74.7mm
YEAH!!!!! add the 86mm crank what do you have???yeah YUMMY!!!
,,,but,,,not really suited for forced induction that well,,,
& Andrew,,,it`s not really a matter of just boring it really big & stroking it really long as there`s other issues,,,avaliability of the correct piston for one,,,the need to skim/machine down the dist drive shaft in some cases is another,,,piston deck heights , gudeon pin sizes & thicknesses & strengths & piston ring suitablility,,,etc etc etc
homework is needed to be done before you just make up your own engine size
we`re currently building a road going turbo charged, 1460cc (bored & stroked) suzuki pistoned engine for young Stew, he`s the one with the Arden crossflow , 6speed dog box, 1600cc powered sports sedan mini shown at the Qld Mini Muster show page in Mini world magazine recently & his new roady turbo engine has had to have the block deck shaved down dramtically to bring the comp ratio back up to reasonable point even with the forced induction, simply cause he got the low deck pistons cheap, go figure,,,:-) we all try to build a donk around what we want as an end result & he goes trying to build one cause he got some pistons & rings cheap, we had some homwork to do there i can tell you
It`s often best to go with a "Known Quantity" rather than trying to make something up from nothing with no experience ,,,& all i can say there is that we`ve allready done the homework on the 1412cc donks,,,we`ve allready done the R&D over the last 30 + years with piston design ...& they`ve been tested for all that time too,,,now that`s a dam good "Known Quantily" in my books
but then,,,i am a little bit biased towards those motors
if you havn`t noticed
But ,,,all that said,,,there`s plenty of combos that work quite well,,,don`t have to do what i say, just do you homework first.
I just hate seeing/hearing of waste,,, waste is wasted goodness.
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