Morris Minor Owners Club

Hmmm - if the rods are 'way' to loose - then maybe you have an early crank - possibly even an EN40B nitrided crank - look for the markings - with Cooper S style conrods. These cranks had the smaller diameter big ends. You NEED to measure the big-ends - for this purpose a digital caliper gauge will be fine. Come back with the size - inches if possible !! It is VERY difficult to move the gudgeon pins in the con rods. I have taken old pistons off rods - where I wasn't too bothered about damaging the pistons cause they were scrap anyway. But to try to fit new pistons to rods - quite a job really. I have heard of it being done with gudgeon pins in the freezer - and the little end of the rod heated up to just short of 'cherry' red - and then the pins pushed through. But I have not done this myself - although I have got hold of a press to have a go in the future - but first trials will be with old pistons.

the crank has the markings "12G1321 EN16T" on one of the webs. The big end journals measure just under 40mm with a cheap caliper. the inside of the bearings fitted to the mini rods appear to be suitable for journals that are 44mm diameter.

There seems to be some contradiction from a bit of googling as to whether the crank is nitrided or not. I assume the "T" suffix is significant in some way?? The problem I have with the pistons that came with the engine is that one of them is different!! it has large oil gaps either side, whereas the other three pistons look the same.

Ok - well 40mm is the smaller diameter all right (was 1.625" but may have been reground slightly) and the 44mm is approx = 1.75" (just under) which is the correct big-end size for most 1275 engines (except the S and some Spridgets). The EN16T is NOT nitrided - that needs EN40B crank - but it may be 'tuftrided' which is a cheaper less effective process. You will certainly need to use the smaller big-end rods !

(except the S and some Spridgets).

I must have one of those engines then. I suppose to upgrade to a crank with 1.75" big ends would be worthwhile? cant see any on ebay though, they are all mini ones.

There are some about.

well the two auction sites im registered on havnt given me any luck. care to shed any light on your last comment bmc???

PM sent!!

and received