bore diameter confusion
Turbo Mini Forums

think i have come to the conclusion of my smoky engine.

i have a set of accralte pistons and on the box it said to bore to 71.63, but on the ring pack it said to bore to 71.12. now when i got the block bored i just gave them the piston and that was that.

when i took off the head to upgrade i found that there was a lot of scoring on the none pin sides of the bores with only 400 miles done, plus there was a lot of movement on the crown to cylinder, eg i could move the piston around quite a lot, i gave it a quick measure with some vernier callipers and came up with 14 thou gap between the crown and the cylinder wall.

i know that pistons do go smaller at the top but i think this ia a little excessive, is what i am trying to find out is if this is my fualt or the machine shop for making the bores too big and how come the measurements are different as said earlier

cheers guys

"Can I legally marry people now that I am ordained in the Church of the SubGenius?" aka i know jack sh"t

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Hi,
I'd be asking Accralite what's going on!
One of the two numbers has got to be wrong, as which ever number you use it will be either wrong for the pistons or wrong for the rings...
Cheers,
Gavin :)

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ye i am trying but they have no conact details, second that found it

Edited by nogin on 16th Jul, 2007.

"Can I legally marry people now that I am ordained in the Church of the SubGenius?" aka i know jack sh"t

i also make things

i love coming home to chrome

nogin on the piston like mine its stamped 73.5 in my case

the machine shop bores and hones the block to to the above figure exactley

the clearence is built in the piston and thats that!

have the machine shop fooked up ???

this is what i need to find out, but i would have thought that the bore would be bored to what oversize the piston was eg 40 thou oversize, will have to strip engine at some piont to find out which is a real shame

"Can I legally marry people now that I am ordained in the Church of the SubGenius?" aka i know jack sh"t

i also make things

i love coming home to chrome

71.63= finished honed .040
71.12 is .020 finished bore. Mega pistons for instance in 020 are uslually 71.06

You cant measure a bore with a verynear gauge.....

alex

AlexF

update,,,,,,,,,,,,,,,,,,, always check what you are putting in your engine even if its labled, i have been running 40thou oversize pistons with 20 thou oversize rings, bit my fault and who ever packed them, phoned up accralite and will be getting a new set of rings in the post tomo, just have to go through the rigmarole of stripping the engine and having it honed

"Can I legally marry people now that I am ordained in the Church of the SubGenius?" aka i know jack sh"t

i also make things

i love coming home to chrome

Hi,
Cheapish escape there! Phew!
Cheers,
Gavin :)

VEMs Authorised Installer / Re-seller. K head kits now available!

WB/EGT gauges. Click here for customers write-up

Visit www.doyouneedabrain.co.uk

My Mini build diary