decking the block?
Turbo Mini Forums

Can anyone please tell me the maximum amount that can be removed from the top of a block? Only reason i ask is i've just bought some new forged cosworth pistons that are 73.5. They are desigened for some sort of triumph? but are very short? These are brand new pistons and were bought VERY cheap so if they are usable it would be great.

Hi,
According to the Vizard bible the 'short' Triumph pistons are 74.7 and you need to remove a large chunk off the block! However it doesn't say how large :( Is it the piston that's short or the compression height?
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

Right took the part number today and decided to phone cosworth. Turns out there not for a truimph as first told There for a cagiva motor bike But all maybe not lost(i hope) dimentions are-

73.4 and bore should be when honed 73.800- 73.815

33.9 top to bottom

21.10ish from top to pin centre

18.00 pin

Are these of any use in a mini and is so in what? long/short/standard stroke? turbo/NA? And im guessing there designed for a high revving motor so no worries about tops coming of Will post a pic later when i get home.

1.515" is the normal from pin centre to top of piston,the viz book says you can take(deck) 3/8" off

Metro turbo weekend driver,Mini turbo in the making again!

Works out about .800" so very short really

Any advise????

use them/Bin them?

Would long stroke help the matter?

Edited by cheekym0nkey on 21st Feb, 2006.

i would not personall use thse in a turbo motor as there is not enough meterial from the piston top cut outs to the first ring.

this is where they most likley will part company, as you search for more boost in the future.

omega cast pistons are well up to the job and wont break the bank. a shade over 200 pounds from MED.

but if you are flushed! go for the acralite ones from avonbar these will last you a lifetime if you keep out of detonation.

thats my oppinion

You can easily deck an A block 7mm. I've
machined a GT block to use with a 70mm stroke crank with standard GT rods. Easy.

A+ should be exactly the same...

i had to deck my block alot to fit a set of accralites i got cheap (73.5mm too) was a long time ago, but from memory i had about 6-7mm removed from the block and left the pistons a bit down the bore to lower CR.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.