entire engine rebuild kit

[picky]

I have a midget 1275 engine that needs completely rebuilding, with new gaskets bearings and rings, is there anywhere that sells the whole lot? Im hoping this would work out cheaper than buying a top engine gasket set, bottom engine gasket set, bearings set and rings set etc...

[bmcecosse]

MOSS will sell you everything. www.moss-europe.co.uk They have a place in Bradford. Look under the Sprite section. But are you SURE rings and bearings will do it (and don't forget a new oil pump) - does it not need reboring and/or crank grinding ? At least if you do all that, it will be like new!

[picky]

there is no noticeable lip in the bores, they are not scored either. The centre main bearings is only just starting to touch the copper, and the big ends look fine. It is probably not required to replace them all, but as I am fitting the supercharger, I want to fit new rings and bearings just to be sure. I have a high capacity pump from minispares to fit also.

I have look in the minispares website, and they have two types of bearings, one being twice the price of the other. Worth investing in "competition" bearings in a road going engine? will they last long enough for a rouad engine... Im not sure.

[bmcecosse]

Well -I used to make engine bearings at Glacier (now Federal Mogul). The cheaper bearings are made of recticular tin/aluminium material - roll bonded to the steel backing. They are perfectly ok in a normal engine. The more expensive bearings are leaded-bronze which is sintered (I developed the induction sintering process) onto a moving strip of steel. These are much more expensive to produce (the leaded bronze powder has to be 'blown' first) - but they are much higher load bearing capacity. They are also 'harder' and so should really be run against a hardened crankshaft - ideally nitrided (as was the Cooper S crank) or tuftrided - as was the MG Metro Turbo engine. That engine also has a redesigned main bearing design - with plain faced shells on the cap half of the bearing - ie there is no oil groove in that half. This increases the load bearing capacity considerably - it was carried over into all 1275 Mini/Metro engines but I don't know if it was carried into the 'in-line' 1275 engines. The way to tell is if the caps have centre 'tang' locations for the shells - while the block will have the normal offset tang locations. To use the harder bearings against a non-hardened crank will tend to invite short wear life of the crank. I think some of the earlier Spridget engines had tuftrided cranks - but I understand this was later dropped as an economy measure. You really must size up the crank very carefully before deciding to just fit new shells. If there is any ovality it will soon knock the bearings out on a high power engine. Budget also for at least a 13 row oil cooler - and lift the oil pressure by adjsuting the spring on the relief valve. And of course - top quality oil !! ASDA oil is ok for normal engines- but if you are s/charging it - spend the extra on the good stuff!

[Kevin]

We have a local company that does all sorts of reconditioning and will also sell you anything from a gasket to a valve you need to find someone local that will offer this sort of service, try these for a start
http://www.autoinsider.co.uk/local/engi ... ing-57.php

[bmcecosse]

That's an interesting site Kevin!

[picky]

back to the bearings for the moment, I have the offset tang type of bearing shells, Is it a worthwhile modification to cut a small notch into the bearing caps to take the 1275 bearings that have a centre tang? the engine is from a 1970 midget so I assume that the crank is not hardenend in any way so to go for the standard bearings will mean the engine lives longer I hope..

How easy is it to check the crank for ovality, I think I can borrow a et of calipers that have 0.1mm accuracy. Put this on the bearing and turn the crank to see how it changes??

[bmcecosse]

You really need to use micrometer - you are looking for 1 thou variation! caliper will tell you nothing. The better bearings will be worth having - if you think you can file the extra notch then go for it!

[RogerRust]

I had a 1275 sprite with a nitrided crank, but I can't remember the part number.

[bmcecosse]

These were few and far between - EN40B steel.

[picky]

I think to use the standard material bearings, the ones with the centre tang and modify the caps to accept them is a good compromise, as hardened cranks are expensive. My micrometer is not big enough to eat the crank bearings Is ovality likely? The centre main bearing was just starting to rub the copper lininng, but the big ends and other main bearings look smooth.

[bmcecosse]

The fact that you are seeing 'copper' lining means they were the stronger leaded bronze shells. It does sound as though all will be well - but it would be nice to have it measured. No-one near you got a big enough micrometer ? Is there any noticeable wear showing - with an unworn path where the oil groove was on the old shells ?

[picky]

if the old bearings were the harder type, and they were starting to wear through doesnt that mean I should see excessive wear on the crank?? if the crank has not been hardened.

[bmcecosse]

Well - it might! Which is why a size check for ovality could be a good idea. But if the crank was hard - (and i dunno how to tell except it's supposedly 'darker') then it should survive ok - which was the point of the hardening of course. Nitrided crank is marked EN40B - yours should probably be EN16 - but not sure if they were marked so.

[Kevin]

You really need to use micrometer - you are looking for 1 thou variation! caliper will tell you nothing.

Agree totally, as a matter of interest if you happen to have a model engineering show near you at any time its worth a visit as they often have tool stalls where the prices of micrometers and the like are much cheaper than elsewhere and it often includes excellent 2nd hand items.

[picky]

I could check whether its darker by comparing it with a spare 1098 crank i have somewhere. the college where I did my A levels (the place where I can borrow the lathe) might have a micrometer big enough. when I go to sort out my pulley I will take the crank and check all the bearing journals. Is 1 thou variation the limit, or too much?

did some googling and read that "most" inline 1275 cranks were tuftrided, "EN16T". Next time Im in the garage I will look for any numbers on the crank.

[bmcecosse]

The cranks will indeed be EN 16T - but by no means 'most' were tuftrided! If this was my project - I would use the crank 'as is' - provided no noticeable ovality - with al/sn bearings - and make sure the oil pressure is kept up by using an oil cooler and a nice new pump - with the relief valve packed up slightly to give 70/75 psi at any decent revs.

[pskipper]

Possibly a daft couple of questions but I'll be starting to strip/rebuild rosies old engine soon so want to make sure I get the right tools. How wide does a micrometer need to stretch for checking the crankshaft and is one which has an accurancy of 0.001 inch suitable?

[bmcecosse]

Oh yes - 1 thou is fine. You will need a 1 - 2 inch micrometer - the 1275 (and some ex late Spridget 1098s) have 2 " main bearings (actually 2.0011/2.0017 ") and big-ends at 1.750 (actually 1.7497/1.7504) - while the 948 and normal 1098 are 1.750 mains (1.7505/1.7512) and 1.625" big ends (1.6252/1.6259). But reading to 1 thou will tell you all you need to know.

[picky]

just bought a set of pistons and rods from a 1979 mini 1275 GT. Tried fitting one of the conrods on my crank and they are way too lose. how difficult is it to swap a set of pistons over to another set of conrods?? I have a strong vice to push the pins in/out. I have a set of pistons with the correct conrods, but I dont want to use these pistons. if that all makes sense