The Duckmeister wrote:
BUMP!!!
A little OT from the previous posts (but this fits just as well here as anywhere else).... I've been trawling around a little bit, and just curious about the different numbers for apparently very similar engines.
I'm inspired in this by the 1275s as much as anything (not the least 'cos I have one) - 12YTaH (Morris 1100S), vs 12H902 (1275 LS) vs whatever was in the Cooper S, as well as whatever else is out there. Basically, what are the differences that determine the different engines?
Morris 1100S up to 12YD/Ta/H10487 were small journal, after that (and in the 12H902 etc 1275LS motors) they used the big journal crank and big heavy rods.
Nothing wrong with the small J ones, (or a Cooper S, which has the same rods) but if you are going to rev a big J one, it's a good idea to either lighten the rods & caps, or fit A+ rods. People also offset grind the big J cranks and use small J rods to build a stroker (you get another 45-50cc).
If you do this it's also a good idea to get the big J crank wedged; this alters the balance factor to reduce uneven main bearing loading & wear.
Cooper S motors are sought after by the Cooper S flat cap brigade and are worth more $$$, so IMO if you are going to build yourself a big HP motor, a non-S block is the one to use. Preferably A series... they are better castings.
[edit] M 1100S automatic and 1300 automatic blocks are fine too, and often can be picked up cheaper, as people think they are just doorstops.
But to work on a manual box they need some oilway mods- see my sticky thread at top in the Mini mods forum:
http://www.ausmini.com/forums/viewtopic.php?t=1461_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.
Like I said, I'm just curious about the differences. Thanks.