17 replies to this topic

[firefox]

Hi Guy's i have had my head off again and took it to another engineer same result nothing the matter with the valve guides but still blowing a lot of smoke light blue smell oil'y so i am going to strip the engine and have it re-bored never had an engine to bit's before but what the hell, anyway the question is i have a chance of a block the has been re-bored +20 new core plugs and cam bearings
on ebay there are some 1275 rings + 20 thou do you think i can use my old pistons crank cam shaft and conrods ect into the new block it has the same engine code 12HA83AA penny's are tight as i have just been made redundant i have read on here that a new oil pump should be fitted that is not a problem and advice please i am at my wits end

[sledgehammer]

Sadly you need new pistons as well as rings , even thou +20 doesn't seem much the old pistons will slap like mad in over sized bores
and the new rings won't be in their grooves as much as they should be

you can still used the crank , con rods , camshaft , ect - providing both engines are a series , or both are A+

while you are there , check the shell bearings as well

best of luck

[firefox]

ohhhhh poo thats not what i wanted to hear but never mind if it has to be new pistons it has to be, have you any idea where the best place is to buy them from, will i need to get the crank re-grinded or will i be able to fit standard shells

[bmcecosse]

Almost certainly it will need a crank grind - but check it all out when you strip down....

[firefox]

Almost certainly it will need a crank grind - but check it all out when you strip down....

Ok bud thanks for that, i am going into the unknown ha ha

[Ethel]

Do your sums, you may be as well off with a replacement engine, but that could be a bit of a gamble too.

[firefox]

Do your sums, you may be as well off with a replacement engine, but that could be a bit of a gamble too.

Yeah thought about that bud, but that is how i have been caught out i bought this one off a friend he got it with a mini he had bought all newley painted nice and shiney put it in and turned out to be a load of crap so its start again time

[Cooperman]

Do your sums, you may be as well off with a replacement engine, but that could be a bit of a gamble too.

Yeah thought about that bud, but that is how i have been caught out i bought this one off a friend he got it with a mini he had bought all newley painted nice and shiney put it in and turned out to be a load of crap so its start again time

Oh, how often do we hear that. There is no short cut or cheap route to a reliable replacement engine. As always, the best advice is to re-bore, new pistons, crank re-grind, new oil pump, timing chain and cam followers, etc., then put it all together very carefully, with help from this forum. Don't be afraid to ask, even if you think it might be a silly question - we are all here to help in any way we can.
Good luck with the re-build.

[firefox]

Do your sums, you may be as well off with a replacement engine, but that could be a bit of a gamble too.

Yeah thought about that bud, but that is how i have been caught out i bought this one off a friend he got it with a mini he had bought all newley painted nice and shiney put it in and turned out to be a load of crap so its start again time

Oh, how often do we hear that. There is no short cut or cheap route to a reliable replacement engine. As always, the best advice is to re-bore, new pistons, crank re-grind, new oil pump, timing chain and cam followers, etc., then put it all together very carefully, with help from this forum. Don't be afraid to ask, even if you think it might be a silly question - we are all here to help in any way we can.
Good luck with the re-build.

Ok Cheers bud, i will and i may as well do as you say i dont want to have to take it out again, the engine is a 12HA83AA mini spares do 20 thou oversize pistons part number P21253-20 i will ring them but your opinion of them would be appreciated

[Cooperman]

The P21253 is an excellent piston. The -xx number is the oversize, so P21253-60 is a +0.060" overbore. It's a high-ish compression piston capable of comp ratios of up to around 11:1 in normally-aspirated engines and will take high revs of up to 6700 rpm or thereabouts. There will be those who have revved them hight and I've used them in a 1330 engine which I revved to 6800+. You can get a cheaper piston, say a P21251, but unless the block is 'decked' the comp. ratio with standard head size is a bit low for good performance. Also the max safe comp ratio and revs will be lower, but they are still quite good pistons for the price.

[sledgehammer]

From my experience at the moment ...
Slightly off subject - but when ordering parts -
look on internet , locate parts you want , then phone them up , and make sure the parts are in stock ,
are the parts they say they are & are ready for dispatch
I've had a mare of a time , with 2 big company's sending out the wrong parts , A's sent out as A+'s
and Item in stock - then waiting 2 weeks , only to be told on back order
best of luck

[firefox]

The P21253 is an excellent piston. The -xx number is the oversize, so P21253-60 is a +0.060" overbore. It's a high-ish compression piston capable of comp ratios of up to around 11:1 in normally-aspirated engines and will take high revs of up to 6700 rpm or thereabouts. There will be those who have revved them hight and I've used them in a 1330 engine which I revved to 6800+. You can get a cheaper piston, say a P21251, but unless the block is 'decked' the comp. ratio with standard head size is a bit low for good performance. Also the max safe comp ratio and revs will be lower, but they are still quite good pistons for the price.

Thats nice to know bud my engine is a high comp 10.1 out of a metro so i will ring them today need to get the block tested first see how much the oversize will be, engineer told me pistons would be about £500 i think he saw me fall on the floor, but he did say that another customer they did a rebore for, not a mini,supplied his own pistons for £80 so he was honest with me so at about 200 dont think thats bad

[firefox]

From my experience at the moment ...
Slightly off subject - but when ordering parts -
look on internet , locate parts you want , then phone them up , and make sure the parts are in stock ,
are the parts they say they are & are ready for dispatch
I've had a mare of a time , with 2 big company's sending out the wrong parts , A's sent out as A+'s
and Item in stock - then waiting 2 weeks , only to be told on back order
best of luck

cheers for the heads up bud

[firefox]

This is a really stupid dumb question, dont laugh to loud, well if you can replace the clutch in situ and you can remove the crank pully and replace the timing chain sprockets ect in situ can i lift the block off and leave the gearbox in, i have got this in my head and need to know if it possible, see with the engine out do you drop the block onto the gearbox or the gearbox onto the block ???

[sledgehammer]

I removed the block on a metro 1300 and left the gearbox in situ years ago - but the engine bay is so much bigger

the worst part is the bonnet slam panel on the Mini - It can't be removed without cutting it , so the block has to be lifted over

putting the block back on the gearbox is really hard as you are so off balance , your feet will want to slip

I would say use an engine crane - you only have one back and even the block on its own is heavy to lift so far away from your body

no easy way out I'm afraid