DAMM PISTON BORES!!!!!
Discussion
I started to clean the 1st bore today,but due to being in my shed for the last couple of years the moisture settled in the bores and left 3/4" ring of rust in each. I was hoping to polish out this rust to find shiny clean surface but to my disappointment there is a tiny lip and are slightly pitted so a rebore is on the cards. My question is do i A: get larger pistons for the metro block and rebore to suit or B:use the block out of my original mini engine (its an economy engine 93-94 so im presuming the bores may be smaller than the metro block?) and rebore to suit the pistons i already have from the metro which would save me money plus i have to strip this engine soon for a few bits anyway so no bother there. If i did go for option (A) i only what to take it as close to 1300cc aspossible -or+, so what size pistons would i need to get for this required cc. thanks in advance...neale...
Edited by dogfather on Thursday 10th April 22:37
hi if the ring you are saying is at the top of the bores thats normal as the rings dont go that high i took my sons to a machine shop and they honed them out at the price of £3 per bore you will need this doing so that your new rings will seat ok
the other thing if the bores are to bad you could bore out to 1293
hope this is some help
david
the other thing if the bores are to bad you could bore out to 1293
hope this is some help
david
Neale,
Standard 1275 block +20" will take you to 1293cc. You state the other "original" Mini engine you have is economy (?) but what cc is it? If your car started life as a Mini Sprite with a 1275cc carb engine with 53ps - the block is entirely compatible - Take the Pistons out of the Metro block that you have - get them measured for wear and any ovality and if they are good to nominal they will run in the original 1275 block out of the Sprite - that way you could keep your costs down.
Other option as you've stated is a +20" rebore to 1293 (you could use either the metro block or your 1275cc Sprite block - makes no odds) and new pistons.
Standard 1275 block +20" will take you to 1293cc. You state the other "original" Mini engine you have is economy (?) but what cc is it? If your car started life as a Mini Sprite with a 1275cc carb engine with 53ps - the block is entirely compatible - Take the Pistons out of the Metro block that you have - get them measured for wear and any ovality and if they are good to nominal they will run in the original 1275 block out of the Sprite - that way you could keep your costs down.
Other option as you've stated is a +20" rebore to 1293 (you could use either the metro block or your 1275cc Sprite block - makes no odds) and new pistons.
Personally, just to be sure that everything is fine, I would take the standard bore block and re-bore to +0.020", use new Hepolite 21253 pistons, set the comp ratio to about 10.3:1.
That will give yoyu a virtually as-new engine with a potentially long-life ahead. I once honed a 998, fitted new rings and after a few thousand miles it was using too much oil, so we had to start again with a re-bore and new pistons.
That will give yoyu a virtually as-new engine with a potentially long-life ahead. I once honed a 998, fitted new rings and after a few thousand miles it was using too much oil, so we had to start again with a re-bore and new pistons.
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