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STGGERED PISTONIES
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Author:  Coop [ Mon Jul 18, 2005 10:34 pm ]
Post subject:  STGGERED PISTONIES
ok i was talking to a mte last nite down at the pub, he told me that hismate has a 1275 or something of that caliber, stroked out to close to 1400, now this is what i want to know .... he said the pistons were "stagered" meaning (this is how he explained it) that the pistons are not lined up in a row, they are stagered
eg: 4 pistons
one closer to the top, the next one closer to the bottom, then top, then bottom
wouldnt this mean that the conrods would ahve to be at a angle to connect to the crank
it sounds like some bs to me

but would be interesting to know if its possible
cheers steve

J E N N I F E R G A R N E R
Author:  kazjim [ Mon Jul 18, 2005 10:38 pm ]
Post subject: 
Could be "Pub Talk" or it could be off-set boring...

Anyone else wnat a go ?

J
Author:  Coop [ Mon Jul 18, 2005 10:41 pm ]
Post subject: 
hmm yeah .... explain off set boring :)
Author:  68matic [ Mon Jul 18, 2005 10:57 pm ]
Post subject: 
Image

pic kinda tells the story
you can squeeze bigger cubes in there

except you probably wouldnt want me to bore your block like that
Author:  Coop [ Mon Jul 18, 2005 11:00 pm ]
Post subject: 
yeah thats it so that off set boring then is it ?
alright ... how does that work does the conrod have to be angled cos the crank would still be straight.... /steve confused
Author:  68matic [ Mon Jul 18, 2005 11:03 pm ]
Post subject: 
mainly you would need a not-so-normal crankshaft
the conrods wouldnt really need to be special unless it was severe
Author:  Stuwey [ Mon Jul 18, 2005 11:15 pm ]
Post subject: 
You can, instead of going front-to-back-to-front-, go further away from each other, so you push them to eac end, but, again, your crank will have to be changed... Sounds ex$pen$ive :(
Author:  Mini Mad [ Mon Jul 18, 2005 11:20 pm ]
Post subject: 
I've never seen it done duc's way :lol:..probably a good thing :), only where they are seperated to give room for larger bore.. ie 1 & 2 and moved towards the radiator 3&4 towards the flywheel...with a bit more spacing..not sure about crank mods..
Author:  drmini in aust [ Mon Jul 18, 2005 11:34 pm ]
Post subject: 
No crank mods are needed for `offset boring'. There is room for the pistons to slide on the gudgeon pins- the bores are not moved far.
Reason for doing it- on a 1275, 2&3 are closer together than 1&2 or 3&4.
Why? Buggered if I know! :lol:

If bored at normal spacing to 74mm (1400cc - for which pistons are now unobtainium) there is too little metal there, it's getting a bit close... :cry:

<edited> for clarity
Author:  benoz [ Tue Jul 19, 2005 3:34 am ]
Post subject: 
VW does that for their narrow angle V engines, I think you'll find that they need to be bored at angles like a V engine.

Either way I reckon your mate might be a bit pissed while trying to explain the offset pistons mentioned by previous posts. A mate of mine who is a genius engine builder was explaining that to me once and for a little while I got the impression that they had been staggered the way you describe, until he put me right
Author:  justminis [ Tue Jul 19, 2005 7:16 am ]
Post subject: 
Offset boring is explained in Vizard's Yelow Bible, done for the purpose of maintaining max meat between 2 & 3. Can be done as Mini Mad says or for really big bores the centreline is also moved slightly toward the push rods holes.
Author:  drmini in aust [ Tue Jul 19, 2005 7:24 am ]
Post subject: 
Steve, big pistons are getting a bit scarce now, I haven't seen 74s for years..
Many people now bore to 73, keeping 73.5 up their sleeve for later.
And you don't have to offset to get to these sizes. :wink:
Author:  FatMaserati [ Tue Jul 19, 2005 1:30 pm ]
Post subject: 
My 1430 is offset bored.
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