10 replies to this topic

[Phaeton]

I have a 1275 MG Metro block, bought some 1380 pistons & was going to have it offset bored to take them. However the block has sleeves in do they all have sleeves or do I need to get another block?

Cheers

Alan...

[miniboo]

depends what size the bores are without the sleeves i suppose

probably best to use a different block though to be honest

[ginigwunkle]

is it std 1275?

they should just bore out the sleeves aswell right?

my 1430 has linings inserted......

[Sprocket]

The question you have to ask yourself is why the sleaves were fitted in the first place. It is very unlikely that it has been sleaved to keep the original pistons due to the original bores being worn, this is a costly exercise and a new set of +20 pistons and an overbore is usualy cheaper. So, to the real reason liners/ sleaves are fitted. They are fitted at the factory to recover what would normaly be rendered scrap due to porous castings.

It is a gamble if you use these blocks as once bored the porous flaws may still be present, and you have then wasted your money. Either it bores fine or it doesnt, and personaly not worth the risk or money.

[alexcrosse]

i went to southam and they said max you can go is 1293 with liners in. Because you have it offset i expect it buggers up all the thermic properties ok the liners because of thicknesses on each side, or it could even turn them into kinda cresent moon shapes.

they often have blocks at mini machinists, i think southam said 30 or 50. Not too bad. i found liners in mine too! 20% of rover 1275's apparently had liners fitted in the factory, they would machine them slightly too much for 1275 pistons, have to take it out further and fit liners, so the block is probably fine in return to sprocket! lol YAY british engineering

Edited by alexcrosse, 20 August 2007 - 11:35 PM.

[Sprocket]

Doubt very much you could bore a linered block to 1380 with the liner still fitted. The thickness of the liner is about 1mm so boring another 1.5mm off the bores removes the liner.

My statement stands regarding the reason for the liners!

[alexcrosse]

indeed it does sprocket, spot on.

basically, youve had bad luck, another block is in order. As i said, u can only go to 1293 with liners. 1380 is offset.

[Phaeton]

The question you have to ask yourself is why the sleaves were fitted in the first place. It is very unlikely that it has been sleaved to keep the original pistons due to the original bores being worn, this is a costly exercise and a new set of +20 pistons and an overbore is usualy cheaper. So, to the real reason liners/ sleaves are fitted. They are fitted at the factory to recover what would normaly be rendered scrap due to porous castings.

It is a gamble if you use these blocks as once bored the porous flaws may still be present, and you have then wasted your money. Either it bores fine or it doesnt, and personaly not worth the risk or money.

Spoke to the machinist today, he's going to remove the linings & set it up for offset boring & see what happens. He's not doing it till Thursday so I suppose I could look for another block as well. Anyone got a very cheap one near Sheffield?

Alan...

[Phaeton]

Been to see if everything has gone okay with the boring. He's a little concerned that cylinders 2 & 3 now only have 130 thou between them is this normal?

Alan...

[Sprocket]

LMFAO

Theres loads there mate, dont know how you managed to get 3.3mm there though, what offsets did he use to machine it.

My 74mm block has only 2.5mm between the center bores and that was with a 10 thou offset

[Phaeton]

Thanks Sprocket, we'll plough on then with Mary's new motor.

Alan...