Morris Minor Owners Club

hi folks, although me and dad both have 1275's, there are two 1098's down the side of the house that he keeps pondering over. some questions he would like answered...
1.what is the biggest oversize you can take a 1098 block to?
2.do other pistons fit in? ie-do 1275 pistons fit?
3.what really is the power gain of a 12g940 head on a 1098 with suitable carb.
bmc...go ahead...

Before the 1275 came into play they used to put Hillman Imp pistons in the 1098 You had to offset some of the bores to fit them in. However I have spoken to a few people who said they smoked badly. Can't really understand why. New bores, new pistons and new rings??

Try finding Hillman Imp pistons at a sane price! From what I could find out, precious little else fits. Ie: All modern engines seem to start around 74mm. Think I decided that the old Skoda 1100 pistons were close, but you aren't likely to find them either! Going for the 1275 head would appear to give you an easy increase in power, coupled with the torque associated with the 1098 crank stroke. That seems a good way to go unless you're looking for a screamer.

It's not going to be worth overboring a 1098 these days - that was done in the old days when there was no 1275 to play with! Obviously you can go to +60 but I doubt it's worth the effort. The 940 head with an HIF 38 and decent inlet manifold will do about 55 bhp - and pull well all through the range - but don't attempt to rev over 6000.

okey dokey! thanks guys, we will soon have two 940 heads spare aswell you see, and also a 1 3/4 su on alloy manifold in the cellar, so it could be a bit of fun!!

I've got a 1098 with an HIF38 carb, 12G295 head and K&N filter fitted. It does give a really useful increase in oomph over the standard engine - so much so that ragging it around Dartmoor earlier today I was continually cooking the brakes squirting the car from corner to corner. A decent exhaust would liberate even more power, making it even more enjoyable to drive.

Chris -when I changed my well worked over 295 head for a 940, I was amazed how much better it went on the 940 ! Yes - the 295 is an excellent head - but the 940 has bigger inlets, bigger exhausts and much better flow in the ports. Bonus - it doesn't need skimmed, down side - it does usually need the exhaust valves sunk into the head by 40 thou.